Combination of inclusive top-quark pair production cross-section measurements using ATLAS and CMS data at $\sqrt{s}= 7$ and 8 TeV

The ATLAS & CMS collaborations Aad, G. ; Abbott, B. ; Abbott, D.C. ; et al.
JHEP 07 (2023) 213, 2023.
Inspire Record 2088291 DOI 10.17182/hepdata.110250

A combination of measurements of the inclusive top-quark pair production cross-section performed by ATLAS and CMS in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV at the LHC is presented. The cross-sections are obtained using top-quark pair decays with an opposite-charge electron-muon pair in the final state and with data corresponding to an integrated luminosity of about 5 fb$^{-1}$ at $\sqrt{s}=7$ TeV and about 20 fb$^{-1}$ at $\sqrt{s}=8$ TeV for each experiment. The combined cross-sections are determined to be $178.5 \pm 4.7$ pb at $\sqrt{s}=7$ TeV and $243.3^{+6.0}_{-5.9}$ pb at $\sqrt{s}=8$ TeV with a correlation of 0.41, using a reference top-quark mass value of 172.5 GeV. The ratio of the combined cross-sections is determined to be $R_{8/7}= 1.363\pm 0.032$. The combined measured cross-sections and their ratio agree well with theory calculations using several parton distribution function (PDF) sets. The values of the top-quark pole mass (with the strong coupling fixed at 0.118) and the strong coupling (with the top-quark pole mass fixed at 172.5 GeV) are extracted from the combined results by fitting a next-to-next-to-leading-order plus next-to-next-to-leading-log QCD prediction to the measurements. Using a version of the NNPDF3.1 PDF set containing no top-quark measurements, the results obtained are $m_t^\text{pole} = 173.4^{+1.8}_{-2.0}$ GeV and $\alpha_\text{s}(m_Z)= 0.1170^{+ 0.0021}_{-0.0018}$.

2 data tables

Full covariance matrix including all systematic uncertainties expressed as nuisance parameters. With the exception of the cross section parameters, all parameters were normalised to 1 before the fit. Therefore, the diagonal elements represent the constraint in quadrature.

Full covariance matrix including all systematic uncertainties expressed as nuisance parameters. With the exception of the cross section parameters, all parameters were normalised to 1 before the fit. Therefore, the diagonal elements represent the constraint in quadrature.


Search for a heavy resonance decaying into a top quark and a W boson in the lepton+jets final state at $\sqrt{s}$= 13 TeV

The CMS collaboration Tumasyan, A. ; Adam, W. ; Andrejkovic, J.W. ; et al.
JHEP 04 (2022) 048, 2022.
Inspire Record 1972089 DOI 10.17182/hepdata.114361

A search for a heavy resonance decaying into a top quark and a W boson in proton-proton collisions at $\sqrt{s} =$ 13 TeV is presented. The data analyzed were recorded with the CMS detector at the LHC and correspond to an integrated luminosity of 138 fb$^{-1}$. The top quark is reconstructed as a single jet and the W boson, from its decay into an electron or muon and the corresponding neutrino. A top quark tagging technique based on jet clustering with a variable distance parameter and simultaneous jet grooming is used to identify jets from the collimated top quark decay. The results are interpreted in the context of two benchmark models, where the heavy resonance is either an excited bottom quark b$^*$ or a vector-like quark B. A statistical combination with an earlier search by the CMS Collaboration in the all-hadronic final state is performed to place upper cross section limits on these two models. The new analysis extends the lower range of resonance mass probed from 1.4 down to 0.7 TeV. For left-handed, right-handed, and vector-like couplings, b$^*$ masses up to 3.0, 3.0, and 3.2 TeV are excluded at 95% confidence level, respectively. The observed upper limits represent the most stringent constraints on the b$^*$ model to date.

7 data tables

Distributions of MtW in the 1b category. The data are shown by filled markers, where the horizontal bars indicate the bin widths. The individual background contributions are given by filled histograms. The expected signal for a LH b* with mb∗ = 2.4 TeV is shown by a dashed line. The shaded region is the uncertainty in the total background estimate. The lower panel shows the ratio of data to the background estimate, with the total uncertainty on the predicted background displayed as the gray band.

Distributions of MtW in the 2b category. The data are shown by filled markers, where the horizontal bars indicate the bin widths. The individual background contributions are given by filled histograms. The expected signal for a LH b* with mb∗ = 2.4 TeV is shown by a dashed line. The shaded region is the uncertainty in the total background estimate. The lower panel shows the ratio of data to the background estimate, with the total uncertainty on the predicted background displayed as the gray band.

Upper limits on the production cross section times branching fraction of the b* LH hypothesis at a 95% CL. Dashed colored lines show the expected limits from the l+jets and all-hadronic channels, where the latter start at resonance masses of 1.4 TeV. The observed and expected limits from the combination are shown as solid and dashed black lines, respectively. The green and yellow bands show the 68 and 95% confidence intervals on the combined expected limits.

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Search for flavor-changing neutral current interactions of the top quark and Higgs boson in final states with two photons in proton-proton collisions at $\sqrt{s}$ = 13 TeV

The CMS collaboration Tumasyan, A. ; Adam, W. ; Andrejkovic, J.W. ; et al.
Phys.Rev.Lett. 129 (2022) 032001, 2022.
Inspire Record 2111572 DOI 10.17182/hepdata.105999

Proton-proton interactions resulting in final states with two photons are studied in a search for the signature of flavor-changing neutral current interactions of top quarks (t) and Higgs bosons (H). The analysis is based on data collected at a center-of-mass energy of 13 TeV with the CMS detector at the LHC, corresponding to an integrated luminosity of 137 fb$^{-1}$. No significant excess above the background prediction is observed. Upper limits on the branching fractions ($\mathcal{B}$) of the top quark decaying to a Higgs boson and an up (u) or charm quark (c) are derived through a binned fit to the diphoton invariant mass spectrum. The observed (expected) 95% confidence level upper limits are found to be 0.019 (0.031)% for $\mathcal B$(t $\to$ Hu) and 0.073 (0.051)% for $\mathcal{B}$(t $\to$ Hc). These are the strictest upper limits yet determined.

1 data table

Expected and observed 95\% CL upper limits on the branching fraction of the top quark decaying to the Higgs boson and a light-flavor quark (either an up or a charm quark)


Search for low-mass dilepton resonances in Higgs boson decays to four-lepton final states in proton-proton collisions at $\sqrt{s}$ =13 TeV

The CMS collaboration Tumasyan, A. ; Adam, W. ; Bergauer, T. ; et al.
Eur.Phys.J.C 82 (2022) 290, 2022.
Inspire Record 1961934 DOI 10.17182/hepdata.110659

A search for low-mass dilepton resonances in Higgs boson decays is conducted in the four-lepton final state. The decay is assumed to proceed via a pair of beyond the standard model particles, or one such particle and a Z boson. The search uses proton-proton collision data collected with the CMS detector at the CERN LHC, corresponding to an integrated luminosity of 137 fb$^{-1}$, at a center-of-mass energy $\sqrt{s} =$ 13 TeV. No significant deviation from the standard model expectation is observed. Upper limits at 95% confidence level are set on model-independent Higgs boson decay branching fractions. Additionally, limits on dark photon and axion-like particle production, based on two specific models, are reported.

9 data tables

Exclusion limit for BrHXX_Br2Xee

Exclusion limit for BrHXX_Br2Xmumu

Exclusion limit for BrHXX_Br2Xll

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Version 3
Search for long-lived particles decaying to jets with displaced vertices in proton-proton collisions at $\sqrt{s}=$ 13 TeV

The CMS collaboration Sirunyan, A.M. ; Tumasyan, A. ; Adam, W. ; et al.
Phys.Rev.D 104 (2021) 052011, 2021.
Inspire Record 1861146 DOI 10.17182/hepdata.102798

A search is presented for long-lived particles produced in pairs in proton-proton collisions at the LHC operating at a center-of-mass energy of 13 TeV. The data were collected with the CMS detector during the period from 2015 through 2018, and correspond to a total integrated luminosity of 140 fb$^{-1}$. This search targets pairs of long-lived particles with mean proper decay lengths between 0.1 and 100 mm, each of which decays into at least two quarks that hadronize to jets, resulting in a final state with two displaced vertices. No significant excess of events with two displaced vertices is observed. In the context of $R$-parity violating supersymmetry models, the pair production of long-lived neutralinos, gluinos, and top squarks is excluded at 95% confidence level for cross sections larger than 0.08 fb, masses between 800 and 3000 GeV, and mean proper decay lengths between 1 and 25 mm.

32 data tables

Event yields in the control samples in data. The ''one-vertex'' events correspond to events containing exactly one vertex with the specified number of tracks. The ''two-vertex'' events have two or more vertices containing the specified numbers of tracks. We seek the signal in the $\geq$5-track two-vertex sample.

The distribution of distances between vertices in the $x$-$y$ plane, $d_{\mathrm{VV}}$, for three simulated multijet signals each with a mass of 1600 GeV, with the background template distribution overlaid. The production cross section for each signal model is assumed to be the lower limit excluded by CMS-EXO-17-018, corresponding to values of 0.8, 0.25, and 0.15 fb for the samples with $c\tau =$ 0.3, 1.0, and 10 mm, respectively. The last bin includes the overflow events. The two vertical pink dashed lines separate the regions used in the fit.

Multijet signal efficiencies as a function of the signal mass and lifetime for events satisfying all event and vertex requirements, with corrections based on systematic differences in the vertex reconstruction efficiency between data and simulation.

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First Measurement of the Muon Neutrino Charged Current Single Pion Production Cross Section on Water with the T2K Near Detector

The T2K collaboration Abe, K. ; Andreopoulos, C. ; Antonova, M. ; et al.
Phys.Rev.D 95 (2017) 012010, 2017.
Inspire Record 1465650 DOI 10.17182/hepdata.73182

The T2K off-axis near detector, ND280, is used to make the first differential cross section measurements of muon neutrino charged current single positive pion production on a water target at energies ${\sim}0.8$ GeV. The differential measurements are presented as a function of muon and pion kinematics, in the restricted phase-space defined by $p_{\pi^+}>200$MeV/c, $p_{\mu^-}>200$MeV/c, $\cos \theta_{\pi^+}>0.3$ and $\cos \theta_{\mu^-}>0.3$. The total flux integrated $\nu_\mu$ charged current single positive pion production cross section on water in the restricted phase-space is measured to be $\langle\sigma\rangle_\phi=4.25\pm0.48 (\mathrm{stat})\pm1.56 (\mathrm{syst})\times10^{-40} \mathrm{cm}^{2}/\mathrm{nucleon}$. The total cross section is consistent with the NEUT prediction ($5.03\times10^{-40} \mathrm{cm}^{2}/\mathrm{nucleon}$) and 2$\sigma$ lower than the GENIE prediction ($7.68\times10^{-40} \mathrm{cm}^{2}/\mathrm{nucleon}$). The differential cross sections are in good agreement with the NEUT generator. The GENIE simulation reproduces well the shapes of the distributions, but over-estimates the overall cross section normalization.

8 data tables

Total $\nu_\mu$ CC1$\pi^+$ cross section on water in the reduced phase-space of $p_{\pi^+} > 200$ MeV/$c$, $p_\mu > 200$ MeV/c, $\cos(\theta_{\pi^+}) > 0.3$ and $\cos(\theta_\mu) > 0.3$. The T2K data point is placed at the $\nu_\mu$ flux mean energy.

Unfolded $\nu_\mu$ CC1$\pi^+$ differential cross section as a function of $p_\pi$ in the reduced phase-space of $p_{\pi^+} > 200$ MeV/$c$, $p_\mu > 200$ MeV/c, $\cos(\theta_{\pi^+}) > 0.3$ and $\cos(\theta_\mu) > 0.3$.

Unfolded $\nu_\mu$ CC1$\pi^+$ differential cross section as a function of $\cos\theta_\pi$ in the reduced phase-space of $p_{\pi^+} > 200$ MeV/$c$, $p_\mu > 200$ MeV/c, $\cos(\theta_{\pi^+}) > 0.3$ and $\cos(\theta_\mu) > 0.3$.

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Measurements of the atmospheric neutrino flux by Super-Kamiokande: energy spectra, geomagnetic effects, and solar modulation

The Super-Kamiokande collaboration Richard, E. ; Okumura, K. ; Abe, K. ; et al.
Phys.Rev.D 94 (2016) 052001, 2016.
Inspire Record 1401192 DOI 10.17182/hepdata.76912

A comprehensive study on the atmospheric neutrino flux in the energy region from sub-GeV up to several TeV using the Super-Kamiokande water Cherenkov detector is presented in this paper. The energy and azimuthal spectra of the atmospheric ${\nu}_e+{\bar{\nu}}_e$ and ${\nu}_{\mu}+{\bar{\nu}}_{\mu}$ fluxes are measured. The energy spectra are obtained using an iterative unfolding method by combining various event topologies with differing energy responses. The azimuthal spectra depending on energy and zenith angle, and their modulation by geomagnetic effects, are also studied. A predicted east-west asymmetry is observed in both the ${\nu}_e$ and ${\nu}_{\mu}$ samples at 8.0 {\sigma} and 6.0 {\sigma} significance, respectively, and an indication that the asymmetry dipole angle changes depending on the zenith angle was seen at the 2.2 {\sigma} level. The measured energy and azimuthal spectra are consistent with the current flux models within the estimated systematic uncertainties. A study of the long-term correlation between the atmospheric neutrino flux and the solar magnetic activity cycle is also performed, and a weak indication of a correlation was seen at the 1.1 {\sigma} level, using SK I-IV data spanning a 20 year period. For particularly strong solar activity periods known as Forbush decreases, no theoretical prediction is available, but a deviation below the typical neutrino event rate is seen at the 2.4 {\sigma} level.

2 data tables

Electron neutrino flux measured by SK I-IV data. Error written in percentage including both statistical and systematic uncertainties.

Muon neutrino flux measured by SK I-IV data. Error written in percentage including both statistical and systematic uncertainties.


Measurement of the muon neutrino inclusive charged-current cross section in the energy range of 1-3 GeV with the T2K INGRID detector

The T2K collaboration Abe, K. ; Andreopoulos, C. ; Antonova, M. ; et al.
Phys.Rev.D 93 (2016) 072002, 2016.
Inspire Record 1394549 DOI 10.17182/hepdata.80058

We report a measurement of the $\nu_{\mu}$-nucleus inclusive charged current cross section (=$\sigma^{cc}$) on iron using data from exposed to the J-PARC neutrino beam. The detector consists of 14 modules in total, which are spread over a range of off-axis angles from 0$^\circ$ to 1.1$^\circ$. The variation in the neutrino energy spectrum as a function of the off-axis angle, combined with event topology information, is used to calculate this cross section as a function of neutrino energy. The cross section is measured to be $\sigma^{cc}(1.1\text{ GeV}) = 1.10 \pm 0.15$ $(10^{-38}\text{cm}^2/\text{nucleon})$, $\sigma^{cc}(2.0\text{ GeV}) = 2.07 \pm 0.27$ $(10^{-38}\text{cm}^2/\text{nucleon})$, and $\sigma^{cc}(3.3\text{ GeV}) = 2.29 \pm 0.45$ $(10^{-38}\text{cm}^2/\text{nucleon})$, at energies of 1.1, 2.0, and 3.3 GeV, respectively. These results are consistent with the cross section calculated by the neutrino interaction generators currently used by T2K. More importantly, the method described here opens up a new way to determine the energy dependence of neutrino-nucleus cross sections.

1 data table

Results of the $\nu_{\mu}$ CC inclusive cross section on Fe.


Measurement of the $\nu_\mu$ CCQE cross section on carbon with the ND280 detector at T2K

The T2K collaboration Abe, K. ; Adam, J. ; Aihara, H. ; et al.
Phys.Rev.D 92 (2015) 112003, 2015.
Inspire Record 1329784 DOI 10.17182/hepdata.72875

The Charged-Current Quasi-Elastic (CCQE) interaction, $\nu_{l} + n \rightarrow l^{-} + p$, is the dominant CC process at $E_\nu \sim 1$ GeV and contributes to the signal in accelerator-based long-baseline neutrino oscillation experiments operating at intermediate neutrino energies. This paper reports a measurement by the T2K experiment of the $\nu_{\mu}$ CCQE cross section on a carbon target with the off-axis detector based on the observed distribution of muon momentum ($p_\mu$) and angle with respect to the incident neutrino beam ($\theta_\mu$). The flux-integrated CCQE cross section was measured to be $(0.83 \pm 0.12) \times 10^{-38}\textrm{ cm}^{2}$ in good agreement with NEUT MC value of ${0.88 \times 10^{-38}} \textrm{ cm}^{2}$. The energy dependence of the CCQE cross section is also reported. The axial mass, $M_A^{QE}$, of the dipole axial form factor was extracted assuming the Smith-Moniz CCQE model with a relativistic Fermi gas nuclear model. Using the absolute (shape-only) $p_{\mu}cos\theta_\mu$ distribution, the effective $M_A^{QE}$ parameter was measured to be ${1.26^{+0.21}_{-0.18} \textrm{ GeV}/c^{2}}$ (${1.43^{+0.28}_{-0.22} \textrm{ GeV}/c^{2}}$).

2 data tables

The measured CCQE energy-dependent cross section per target neutron.

The fractional covariance matrix corresponding to the errors shown in Figure 7.


Energy Dependence of $K/\pi$, $p/\pi$, and $K/p$ Fluctuations in Au+Au Collisions from $\rm \sqrt{s_{NN}}$ = 7.7 to 200 GeV

The STAR collaboration Abdelwahab, N.M. ; Adamczyk, L. ; Adkins, J.K. ; et al.
Phys.Rev.C 92 (2015) 021901, 2015.
Inspire Record 1322965 DOI 10.17182/hepdata.72254

A search for the quantum chromodynamics (QCD) critical point was performed by the STAR experiment at the Relativistic Heavy Ion Collider, using dynamical fluctuations of unlike particle pairs. Heavy-ion collisions were studied over a large range of collision energies with homogeneous acceptance and excellent particle identification, covering a significant range in the QCD phase diagram where a critical point may be located. Dynamical $K\pi$, $p\pi$, and $Kp$ fluctuations as measured by the STAR experiment in central 0-5\% Au+Au collisions from center-of-mass collision energies $\rm \sqrt{s_{NN}}$ = 7.7 to 200 GeV are presented. The observable $\rm \nu_{dyn}$ was used to quantify the magnitude of the dynamical fluctuations in event-by-event measurements of the $K\pi$, $p\pi$, and $Kp$ pairs. The energy dependences of these fluctuations from central 0-5\% Au+Au collisions all demonstrate a smooth evolution with collision energy.

1 data table

$p\pi$, Kp, and $K\pi$ fluctuations as a function of collision energy, expressed as $v_{dyn,p\pi}$, $v_{dyn,Kp}$, and $v_{dyn,K\pi}$ respectively. Shown are data from central (0-5%) Au+Au collisions at energies from $\sqrt{s_{\rm NN}}$ = 7.7 to 200 GeV from the STAR experiment.


Di-Hadron Correlations with Identified Leading Hadrons in 200 GeV Au+Au and d+Au Collisions at STAR

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Lett.B 751 (2015) 233-240, 2015.
Inspire Record 1322126 DOI 10.17182/hepdata.73458

The STAR collaboration presents for the first time two-dimensional di-hadron correlations with identified leading hadrons in 200 GeV central Au+Au and minimum-bias d+Au collisions to explore hadronization mechanisms in the quark gluon plasma. The enhancement of the jet-like yield for leading pions in Au+Au data with respect to the d+Au reference and the absence of such an enhancement for leading non-pions (protons and kaons) are discussed within the context of a quark recombination scenario. The correlated yield at large angles, specifically in the \emph{ridge region}, is found to be significantly higher for leading non-pions than pions. The consistencies of the constituent quark scaling, azimuthal harmonic model and a mini-jet modification model description of the data are tested, providing further constraints on hadronization.

14 data tables

Two-dimensional $\Delta\phi$ vs. $\Delta\eta$ correlation functions for charged hadron triggers from minimum-bias d+Au data at 200 GeV. All trigger and associated charged hadrons are selected in the respective pT ranges 4 < $p_T^{trig}$ < 5 GeV/c and 1.5 < $p_T^{assoc}$ < 4 GeV/c.

Two-dimensional $\Delta\phi$ vs. $\Delta\eta$ correlation functions for charged hadron triggers from 0-10% most-central Au+Au data at 200 GeV. All trigger and associated charged hadrons are selected in the respective pT ranges 4 < $p_T^{trig}$ < 5 GeV/c and 1.5 < $p_T^{assoc}$ < 4 GeV/c.

Two-dimensional $\Delta\phi$ vs. $\Delta\eta$ correlation functions for non-pion triggers from minimum-bias d+Au data at 200 GeV. All trigger and associated charged hadrons are selected in the respective pT ranges 4 < $p_T^{trig}$ < 5 GeV/c and 1.5 < $p_T^{assoc}$ < 4 GeV/c.

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Isolation of Flow and Nonflow Correlations by Two- and Four-Particle Cumulant Measurements of Azimuthal Harmonics in $\sqrt{s_{_{\rm NN}}} =$ 200 GeV Au+Au Collisions

The STAR collaboration Abdelwahab, N.M. ; Adamczyk, L. ; Adkins, J.K. ; et al.
Phys.Lett.B 745 (2015) 40-47, 2015.
Inspire Record 1315466 DOI 10.17182/hepdata.73493

A data-driven method was applied to measurements of Au+Au collisions at $\sqrt{s_{_{\rm NN}}} =$ 200 GeV made with the STAR detector at RHIC to isolate pseudorapidity distance $\Delta\eta$-dependent and $\Delta\eta$-independent correlations by using two- and four-particle azimuthal cumulant measurements. We identified a component of the correlation that is $\Delta\eta$-independent, which is likely dominated by anisotropic flow and flow fluctuations. It was also found to be independent of $\eta$ within the measured range of pseudorapidity $|\eta|<1$. The relative flow fluctuation was found to be $34\% \pm 2\% (stat.) \pm 3\% (sys.)$ for particles of transverse momentum $p_{T}$ less than $2$ GeV/$c$. The $\Delta\eta$-dependent part may be attributed to nonflow correlations, and is found to be $5\% \pm 2\% (sys.)$ relative to the flow of the measured second harmonic cumulant at $|\Delta\eta| > 0.7$.

27 data tables

The second harmonic two-particle cumulants for ($\eta_{\alpha}$, $\eta_{\beta}$ pairs for 20-30% central Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV.

The third harmonic two-particle cumulants for ($\eta_{\alpha}$, $\eta_{\beta}$ pairs for 20-30% central Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV.

The second harmonic four-particle cumulant for ($\eta_{\alpha}$, $\eta_{\alpha}$, $\eta_{\beta}$, $\eta_{\beta}$) quadruplets for 20-30% central Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV.

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Charged-to-neutral correlation at forward rapidity in Au+Au collisions at $\sqrt{s_{NN}}$=200 GeV

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.C 91 (2015) 034905, 2015.
Inspire Record 1311834 DOI 10.17182/hepdata.73610

Event-by-event fluctuations of the ratio of inclusive charged to photon multiplicities at forward rapidity in Au+Au collision at $\sqrt{s_{NN}}$=200 GeV have been studied. Dominant contribution to such fluctuations is expected to come from correlated production of charged and neutral pions. We search for evidences of dynamical fluctuations of different physical origins. Observables constructed out of moments of multiplicities are used as measures of fluctuations. Mixed events and model calculations are used as baselines. Results are compared to the dynamical net-charge fluctuations measured in the same acceptance. A non-zero statistically significant signal of dynamical fluctuations is observed in excess to the model prediction when charged particles and photons are measured in the same acceptance. We find that, unlike dynamical net-charge fluctuation, charge-neutral fluctuation is not dominated by correlation due to particle decay. Results are compared to the expectations based on the generic production mechanism of pions due to isospin symmetry, for which no significant (<1%) deviation is observed.

21 data tables

Multiplicity distributions of raw charged particles and photons.

The $v_{dyn}$ and the three terms of $v_{dyn}$ vs $\sqrt{\langle N_{ch}\rangle \langle N_{\gamma}\rangle }$ for real events. $\omega_{ch}^{real}$ is plotted.

The $v_{dyn}$ and the three terms of $v_{dyn}$ vs $\sqrt{\langle N_{ch}\rangle \langle N_{\gamma}\rangle }$ for mixed events. $\omega_{ch}^{mixed}$ is plotted.

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The $\Lambda\Lambda$ Correlation Function in Au+Au collisions at $\sqrt{s_{NN}}=$ 200 GeV

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.Lett. 114 (2015) 022301, 2015.
Inspire Record 1311513 DOI 10.17182/hepdata.73492

We present $\Lambda\Lambda$ correlation measurements in heavy-ion collisions for Au+Au collisions at $\sqrt{s_{NN}}= 200$ GeV using the STAR experiment at the Relativistic Heavy-Ion Collider (RHIC). The Lednick\'{y}-Lyuboshitz analytical model has been used to fit the data to obtain a source size, a scattering length and an effective range. Implications of the measurement of the $\Lambda\Lambda$ correlation function and interaction parameters for di-hyperon searches are discussed.

4 data tables

The invariant mass distribution for $\Lambda$ and $\bar{\Lambda}$ produced in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV, for 0-80% centrality. The $\Lambda$ and $\bar{\Lambda}$ candidates lying in the mass range 1.112 to 1.120 GeV/c^2 were selected for the correlation measurement.

The $\Lambda\Lambda$ and $\bar{\Lambda}\bar{\Lambda}$ correlation function in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV, for 0-80% centrality.

The combined $\Lambda\Lambda$ and $\bar{\Lambda}\bar{\Lambda}$ correlation function for 0-80% centrality Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV.

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Elliptic flow of non-photonic electrons in Au+Au collisions at $\sqrt{s_{\rm NN}} = $ 200, 62.4 and 39 GeV

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.C 95 (2017) 034907, 2017.
Inspire Record 1298024 DOI 10.17182/hepdata.77016

We present measurements of elliptic flow ($v_2$) of electrons from the decays of heavy-flavor hadrons ($e_{HF}$) by the STAR experiment. For Au+Au collisions at $\sqrt{s_{\rm NN}} = $ 200 GeV we report $v_2$, for transverse momentum ($p_T$) between 0.2 and 7 GeV/c using three methods: the event plane method ($v_{2}${EP}), two-particle correlations ($v_2${2}), and four-particle correlations ($v_2${4}). For Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 62.4 and 39 GeV we report $v_2${2} for $p_T< 2$ GeV/c. $v_2${2} and $v_2${4} are non-zero at low and intermediate $p_T$ at 200 GeV, and $v_2${2} is consistent with zero at low $p_T$ at other energies. The $v_2${2} at the two lower beam energies is systematically lower than at $\sqrt{s_{\rm NN}} = $ 200 GeV for $p_T < 1$ GeV/c. This difference may suggest that charm quarks interact less strongly with the surrounding nuclear matter at those two lower energies compared to $\sqrt{s_{\rm NN}} = 200$ GeV.

18 data tables

Signal-to-background (S/B) ratio as a function of transverse momentum, Au+Au 200 GeV, 0-60% central events with minimum bias trigger

Signal-to-background (S/B) ratio as a function of transverse momentum, Au+Au 200 GeV, 0-60% central events with with High Tower (high pT) trigger

Signal-to-background (S/B) ratio as a function of transverse momentum, Au+Au 39 GeV, 0-60% central events with minimum bias trigger

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Precision Measurement of the Longitudinal Double-spin Asymmetry for Inclusive Jet Production in Polarized Proton Collisions at $\sqrt{s}=200$ GeV

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.Lett. 115 (2015) 092002, 2015.
Inspire Record 1297229 DOI 10.17182/hepdata.73432

We report a new high-precision measurement of the mid-rapidity inclusive jet longitudinal double-spin asymmetry, $A_{LL}$, in polarized $pp$ collisions at center-of-mass energy $\sqrt{s}=200$ GeV. The STAR data place stringent constraints on polarized parton distribution functions extracted at next-to-leading order from global analyses of inclusive deep inelastic scattering (DIS), semi-inclusive DIS, and RHIC $pp$ data. The measured asymmetries provide evidence for positive gluon polarization in the Bjorken-$x$ region $x>0.05$.

7 data tables

Jet neutral energy fraction (NEF) comparing data with simulations, where both are calculated with pT subtraction. This plot shows 8.4 < $p_T$ < 9.9 GeV/c.

Jet neutral energy fraction (NEF) comparing data with simulations, where both are calculated with pT subtraction. This plot shows 26.8 < $p_T$ < 31.6 GeV/c.

Inclusive jet $A_{LL}$ vs. parton jet $p_T$ for |eta|<0.5.

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Measurement of longitudinal spin asymmetries for weak boson production in polarized proton-proton collisions at RHIC

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.Lett. 113 (2014) 072301, 2014.
Inspire Record 1292792 DOI 10.17182/hepdata.73441

We report measurements of single- and double- spin asymmetries for $W^{\pm}$ and $Z/\gamma^*$ boson production in longitudinally polarized $p+p$ collisions at $\sqrt{s} = 510$ GeV by the STAR experiment at RHIC. The asymmetries for $W^{\pm}$ were measured as a function of the decay lepton pseudorapidity, which provides a theoretically clean probe of the proton's polarized quark distributions at the scale of the $W$ mass. The results are compared to theoretical predictions, constrained by recent polarized deep inelastic scattering measurements, and show a preference for a sizable, positive up antiquark polarization in the range $0.05<x<0.2$.

13 data tables

$E_T^e$ distribution of $W^{\pm}$ candidate events, background contributions, and sum of backgrounds and W -> ev MC signal. This plot is for Electron |eta|<0.5.

$E_T^e$ distribution of $W^{\pm}$ candidate events, background contributions, and sum of backgrounds and W -> ev MC signal. This plot is for Electron 0.5<|eta|<1.1.

$E_T^e$ distribution of $W^{\pm}$ candidate events, background contributions, and sum of backgrounds and W -> ev MC signal. This plot is for Positron |eta|<0.5.

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Version 3
Observation of $D^0$ meson nuclear modifications in Au+Au collisions at $\sqrt{s_{_{\mathrm{NN}}}}$ = 200 GeV

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.Lett. 113 (2014) 142301, 2014.
Inspire Record 1292132 DOI 10.17182/hepdata.73474

In this erratum we report changes on the $D^0$ $p_T$ spectra and nuclear modification factor ($R_{AA}$) in Au+Au collisions at $\sqrt{s_{_{\mathrm{NN}}}}$ = 200 GeV by fixing the errors in the efficiency and selection criteria that affected the Au+Au results. The p+p reference spectrum has changed as well and is updated with new fragmentation parameters.

4 data tables

$D^0$ $p_{\rm T}$ differential invariant yield in p+p collisions (open circles), which has been updated with the latest global analysis of charm fragmentation ratios from Ref and also taking into account the $p_{\rm T}$ dependence of the fragmentation ratio between $D^0$ and $D^{*{\pm}}$ from PYTHIA 6.4. The systematic uncertainties are shown as square brackets.

Centrality dependence of the $D^0$ $p_{\rm T}$ differential invariant yield in Au+Au collisions (solid symbols). The curves are number-of-binary-collision-scaled Levy functions from fitting to the p+p result (open circles), which has been updated with the latest global analysis of charm fragmentation ratios from Ref and also taking into account the $p_{\rm T}$ dependence of the fragmentation ratio between $D^0$ and $D^{*{\pm}}$ from PYTHIA 6.4. The arrow denotes the upper limit with 90% confidence level of the last data point for 10$-$40% collisions. The systematic uncertainties are shown as square brackets.

Panels (ab), $D^0$ $R_{\rm AA}$ for peripheral 40$-$80% and semi a central 10$-$40% collisions; Panel (c), $D^0$ $R_{\rm AA}$ for 0$-$10% most central events (blue circles) compared with model calculations from the TAMU (solid curve), SUBATECH (dashed curve), Torino (dot-dashed curve), Duke (long-dashed and long-dot-dashed curves), and LANL groups (filled band). The open symbol indicates the result with the extrapolated p+p reference. The vertical lines and brackets around the data points denote the statistical and systematic uncertainties respectively. The vertical bars around unity denote the overall normalization uncertainties in the Au+Au and p+p data, respectively. The $R_{\rm AA}$ probability distribution for the 0$-$0.7 GeV/$c$ data point is largely skewed. The uncertainty we report is the 68.3% probability range with respect to the measured central value assuming Gaussian distribution.

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Beam-energy dependence of charge separation along the magnetic field in Au+Au collisions at RHIC

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.Lett. 113 (2014) 052302, 2014.
Inspire Record 1288917 DOI 10.17182/hepdata.73457

Local parity-odd domains are theorized to form inside a Quark-Gluon-Plasma (QGP) which has been produced in high-energy heavy-ion collisions. The local parity-odd domains manifest themselves as charge separation along the magnetic field axis via the chiral magnetic effect (CME). The experimental observation of charge separation has previously been reported for heavy-ion collisions at the top RHIC energies. In this paper, we present the results of the beam-energy dependence of the charge correlations in Au+Au collisions at midrapidity for center-of-mass energies of 7.7, 11.5, 19.6, 27, 39 and 62.4 GeV from the STAR experiment. After background subtraction, the signal gradually reduces with decreased beam energy, and tends to vanish by 7.7 GeV. The implications of these results for the CME will be discussed.

15 data tables

The three-point correlator, $\gamma$, as a function of centrality for Au+Au collisions at 62.4 GeV.

The three-point correlator, $\gamma$, as a function of centrality for Au+Au collisions at 39 GeV.

The three-point correlator, $\gamma$, as a function of centrality for Au+Au collisions at 27 GeV.

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Beam energy dependent two-pion interferometry and the freeze-out eccentricity of pions in heavy ion collisions at STAR

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.C 92 (2015) 014904, 2015.
Inspire Record 1286656 DOI 10.17182/hepdata.96391

We present results of analyses of two-pion interferometry in Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7, 11.5, 19.6, 27, 39, 62.4 and 200 GeV measured in the STAR detector as part of the RHIC Beam Energy Scan program. The extracted correlation lengths (HBT radii) are studied as a function of beam energy, azimuthal angle relative to the reaction plane, centrality, and transverse mass ($m_{T}$) of the particles. The azimuthal analysis allows extraction of the eccentricity of the entire fireball at kinetic freeze-out. The energy dependence of this observable is expected to be sensitive to changes in the equation of state. A new global fit method is studied as an alternate method to directly measure the parameters in the azimuthal analysis. The eccentricity shows a monotonic decrease with beam energy that is qualitatively consistent with the trend from all model predictions and quantitatively consistent with a hadronic transport model.

43 data tables

Angular oscillations of the HBT radii relative to the event plane from 20-30% central, 19.6 GeV Au+Au collisions for 0.15 < kT < 0.6 GeV/c. HHLW Radii uncorrected for resolution and binning for $R_{out}$.

Angular oscillations of the HBT radii relative to the event plane from 20-30% central, 19.6 GeV Au+Au collisions for 0.15 < kT < 0.6 GeV/c. HHLW Radii for resolution and binning for $R_{out}$, $R_{side}$, $R_{long}$, $R_{os}$, and $R_{ol}$ respectively.

Angular oscillations of the HBT radii relative to the event plane from 20-30% central, 19.6 GeV Au+Au collisions for 0.15 < kT < 0.6 GeV/c. Radius values according to global fit of Fourier Coefficients for $R_{out}$, $R_{side}$, $R_{long}$, $R_{os}$, and $R_{ol}$ respectively.

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Dielectron Azimuthal Anisotropy at mid-rapidity in Au+Au collisions at $\sqrt{s_{_{NN}}} = 200$ GeV

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.C 90 (2014) 064904, 2014.
Inspire Record 1280745 DOI 10.17182/hepdata.96269

We report on the first measurement of the azimuthal anisotropy ($v_2$) of dielectrons ($e^{+}e^{-}$ pairs) at mid-rapidity from $\sqrt{s_{_{NN}}} = 200$ GeV Au+Au collisions with the STAR detector at RHIC, presented as a function of transverse momentum ($p_T$) for different invariant-mass regions. In the mass region $M_{ee}\!<1.1$ GeV/$c^2$ the dielectron $v_2$ measurements are found to be consistent with expectations from $\pi^{0}$, $\eta$, $\omega$ and $\phi$ decay contributions. In the mass region $1.1\!<M_{ee}\!<2.9$ GeV/$c^2$, the measured dielectron $v_2$ is consistent, within experimental uncertainties, with that from the $c\bar{c}$ contributions.

17 data tables

The dielectron $v_2$ in the $\pi^0$ Dalitz decay region as a function of $p_T$ in different centralities from Au + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV.

Expected dielectron $v_2$ from $\pi^0$ Dalitz decay as a function of $p_T$ in different centralities from Au + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV.

The dielectron $v_2$ as a function of $p_T$ in minimum-bias Au + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV for the $\pi^0$ mass region.

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Beam energy dependence of moments of the net-charge multiplicity distributions in Au+Au collisions at RHIC

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.Lett. 113 (2014) 092301, 2014.
Inspire Record 1280557 DOI 10.17182/hepdata.105915

We report the first measurements of the moments -- mean ($M$), variance ($\sigma^{2}$), skewness ($S$) and kurtosis ($\kappa$) -- of the net-charge multiplicity distributions at mid-rapidity in Au+Au collisions at seven energies, ranging from $\sqrt {{s_{\rm NN}}}$= 7.7 to 200 GeV, as a part of the Beam Energy Scan program at RHIC. The moments are related to the thermodynamic susceptibilities of net-charge, and are sensitive to the proximity of the QCD critical point. We compare the products of the moments, $\sigma^{2}/M$, $S\sigma$ and $\kappa\sigma^{2}$ with the expectations from Poisson and negative binomial distributions (NBD). The $S\sigma$ values deviate from Poisson and are close to NBD baseline, while the $\kappa\sigma^{2}$ values tend to lie between the two. Within the present uncertainties, our data do not show non-monotonic behavior as a function of collision energy. These measurements provide a distinct way of determining the freeze-out parameters in heavy-ion collisions by comparing with theoretical models.

45 data tables

The efficiency and centrality bin width corrected mean (M) of the net-charge multiplicity distributions as a function of number of participating nucleons $N_{part}$ for Au+Au collisions at 7.7 GeV. The dotted lines represent calculations from the central limit theorem. The error bars are statisticaland systematic errors.

The efficiency and centrality bin width corrected mean (M) of the net-charge multiplicity distributions as a function of number of participating nucleons $N_{part}$ for Au+Au collisions at 11.5 GeV. The dotted lines represent calculations from the central limit theorem. The error bars are statisticaland systematic errors.

The efficiency and centrality bin width corrected mean (M) of the net-charge multiplicity distributions as a function of number of participating nucleons $N_{part}$ for Au+Au collisions at 19.6 GeV. The dotted lines represent calculations from the central limit theorem. The error bars are statisticaland systematic errors.

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Beam-Energy Dependence of Directed Flow of Protons, Antiprotons and Pions in Au+Au Collisions

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.Lett. 112 (2014) 162301, 2014.
Inspire Record 1277069 DOI 10.17182/hepdata.105867

Rapidity-odd directed flow($v_1$) measurements for charged pions, protons and antiprotons near mid-rapidity ($y=0$) are reported in $\sqrt{s_{NN}} =$ 7.7, 11.5, 19.6, 27, 39, 62.4 and 200 GeV Au + Au collisions as recorded by the STAR detector at the Relativistic Heavy Ion Collider (RHIC). At intermediate impact parameters, the proton and net-proton slope parameter $dv_1/dy|_{y=0}$ shows a minimum between 11.5 and 19.6 GeV. In addition, the net-proton $dv_1/dy|_{y=0}$ changes sign twice between 7.7 and 39 GeV. The proton and net-proton results qualitatively resemble predictions of a hydrodynamic model with a first-order phase transition from hadronic matter to deconfined matter, and differ from hadronic transport calculations.

6 data tables

Directed flow for protons versus rapidity for central (0-10$\%$), intermediate-centrality (10-40$\%$) and peripheral (40-80$\%$) Au+Au collisions at $\sqrt{s_{NN}}$ = 39, 27, 19.6, 11.5 and 7.7 GeV. Errors are statistical only.

Directed flow for $\pi^{-}$ versus rapidity for central (0-10$\%$), intermediate-centrality (10-40$\%$) and peripheral (40-80$\%$) Au+Au collisions at $\sqrt{s_{NN}}$ = 39, 27, 19.6, 11.5 and 7.7 GeV. Errors are statistical only.

Directed flow for protons and anti-protons versus rapidity for intermediate-centrality (10-40$\%$) Au+Au collisions at $\sqrt{s_{NN}}$ = 200, 62.4, 39, 27, 19.6, 11.5 and 7.7 GeV. Errors are statistical only.

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Dielectron Mass Spectra from Au+Au Collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.Lett. 113 (2014) 022301, 2014.
Inspire Record 1275614 DOI 10.17182/hepdata.95663

We report the STAR measurements of dielectron ($e^+e^-$) production at midrapidity ($|y_{ee}|<$1) in Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200\,GeV. The measurements are evaluated in different invariant mass regions with a focus on 0.30-0.76 ($\rho$-like), 0.76-0.80 ($\omega$-like), and 0.98-1.05 ($\phi$-like) GeV/$c^{2}$. The spectrum in the $\omega$-like and $\phi$-like regions can be well described by the hadronic cocktail simulation. In the $\rho$-like region, however, the vacuum $\rho$ spectral function cannot describe the shape of the dielectron excess. In this range, an enhancement of 1.77$\pm$0.11(stat.)$\pm$0.24(sys.)$\pm$0.33(cocktail) is determined with respect to the hadronic cocktail simulation that excludes the $\rho$ meson. The excess yield in the $\rho$-like region increases with the number of collision participants faster than the $\omega$ and $\phi$ yields. Theoretical models with broadened $\rho$ contributions through interactions with constituents in the hot QCD medium provide a consistent description of the dilepton mass spectra for the measurement presented here and the earlier data at the Super Proton Synchrotron energies.

11 data tables

Uncorrected Distributions of e+ e- invariant mass, the reconstructed background, and the signal pairs in 200 GeV Au+Au minimum bias collisions.

The ratio of signal to background in Au + Au collisions at $\sqrt{s_{{NN}}}$ = 200 GeV (Minimum Bias).

The ratio of signal to background in Au + Au collisions at $\sqrt{s_{{NN}}}$ = 200 GeV (Central).

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Suppression of Upsilon Production in d+Au and Au+Au Collisions at sqrt(s_NN) = 200 GeV

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Lett.B 735 (2014) 127-137, 2014.
Inspire Record 1269346 DOI 10.17182/hepdata.102940

We report measurements of Upsilon meson production in p+p, d+Au, and Au+Au collisions using the STAR detector at RHIC. We compare the Upsilon yield to the measured cross section in p+p collisions in order to quantify any modifications of the yield in cold nuclear matter using d+Au data and in hot nuclear matter using Au+Au data separated into three centrality classes. Our p+p measurement is based on three times the statistics of our previous result. We obtain a nuclear modification factor for Upsilon(1S+2S+3S) in the rapidity range |y|<1 in d+Au collisions of R_dAu = 0.79 +/- 0.24 (stat.) +/- 0.03 (sys.) +/- 0.10 (pp sys.). A comparison with models including shadowing and initial state parton energy loss indicates the presence of additional cold-nuclear matter suppression. Similarly, in the top 10% most-central Au+Au collisions, we measure a nuclear modification factor of R_AA=0.49 +/- 0.1 (stat.) +/- 0.02 (sys.) +/- 0.06 (pp sys.), which is a larger suppression factor than that seen in cold nuclear matter. Our results are consistent with complete suppression of excited-state Upsilon mesons in Au+Au collisions. The additional suppression in Au+Au is consistent with the level expected in model calculations that include the presence of a hot, deconfined Quark-Gluon Plasma. However, understanding the suppression seen in d+Au is still needed before any definitive statements about the nature of the suppression in Au+Au can be made.

14 data tables

Invariant mass distributions of electron pairs in the region $|y_{ee}| < 0.5$, p+p.

Invariant mass distributions of electron pairs in the region $|y_{ee}| < 0.5$, d+Au.

(a) $B_{ee} \times d\sigma/dy$ vs. $y$ for p+p collisions and for d+Au collisions (scaled down by 103).

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$J/\psi$ polarization in p+p collisions at $\sqrt{s}$ = 200 GeV in STAR

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Lett.B 739 (2014) 180-188, 2014.
Inspire Record 1263695 DOI 10.17182/hepdata.96232

We report on a polarization measurement of inclusive $J/\psi$ mesons in the di-electron decay channel at mid-rapidity at 2 $<p_{T}<$ 6 GeV/$c$ in $p+p$ collisions at $\sqrt{s}$ = 200 GeV. Data were taken with the STAR detector at RHIC. The $J/\psi$ polarization measurement should help to distinguish between different models of the $J/\psi$ production mechanism since they predict different $p_{T}$ dependences of the $J/\psi$ polarization. In this analysis, $J/\psi$ polarization is studied in the helicity frame. The polarization parameter $\lambda_{\theta}$ measured at RHIC becomes smaller towards high $p_{T}$, indicating more longitudinal $J/\psi$ polarization as $p_{T}$ increases. The result is compared with predictions of presently available models.

13 data tables

Uncorrected cos$\theta$ distribution after the combinatorial background subtraction for $2 < p_{T}^{J/\psi} < 3$ GeV/c

Uncorrected cos$\theta$ distribution after the combinatorial background subtraction for $3 < p_{T}^{J/\psi} < 4$ GeV/c

Uncorrected cos$\theta$ distribution after the combinatorial background subtraction for $4 < p_{T}^{J/\psi} < 6$ GeV/c

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$J/\psi$ production at low $p_T$ in Au+Au and Cu+Cu collisions at $\sqrt{s_{_{NN}}}$ = 200 GeV at STAR

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.C 90 (2014) 024906, 2014.
Inspire Record 1258446 DOI 10.17182/hepdata.99158

The $\jpsi$ $\pt$ spectrum and nuclear modification factor ($\raa$) are reported for $\pt < 5 \ \gevc$ and $|y|<1$ from 0\% to 60\% central Au+Au and Cu+Cu collisions at $\snn = 200 \ \gev$ at STAR. A significant suppression of $\pt$-integrated $\jpsi$ production is observed in central Au+Au events. The Cu+Cu data are consistent with no suppression, although the precision is limited by the available statistics. $\raa$ in Au+Au collisions exhibits a strong suppression at low transverse momentum and gradually increases with $\pt$. The data are compared to high-$\pt$ STAR results and previously published BNL Relativistic Heavy Ion Collider results. Comparing with model calculations, it is found that the invariant yields at low $\pt$ are significantly above hydrodynamic flow predictions but are consistent with models that include color screening and regeneration.

11 data tables

The invariant yield versus transverse momentum for |y| < 1 in 0-20% centrality in Au+Au collisions (solid circles). The results are compared to high-$p_T$ (3 < $p_T$ < 10 GeV/c) results from STAR [9] (solid squares) and PHENIX data [8] (open squares).

The invariant yield versus transverse momentum for |y| < 1 in 20-40% centrality in Au+Au collisions (solid circles). The results are compared to high-$p_T$ (3 < $p_T$ < 10 GeV/c) results from STAR [9] (solid squares) and PHENIX data [8] (open squares).

The invariant yield versus transverse momentum for |y| < 1 in 40-60% centrality in Au+Au collisions (solid circles). The results are compared to high-$p_T$ (3 < $p_T$ < 10 GeV/c) results from STAR [9] (solid squares) and PHENIX data [8] (open squares).

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Energy Dependence of Moments of Net-proton Multiplicity Distributions at RHIC

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.Lett. 112 (2014) 032302, 2014.
Inspire Record 1255072 DOI 10.17182/hepdata.73343

We report the beam energy (\sqrt s_{NN} = 7.7 - 200 GeV) and collision centrality dependence of the mean (M), standard deviation (\sigma), skewness (S), and kurtosis (\kappa) of the net-proton multiplicity distributions in Au+Au collisions. The measurements are carried out by the STAR experiment at midrapidity (|y| < 0.5) and within the transverse momentum range 0.4 < pT < 0.8 GeV/c in the first phase of the Beam Energy Scan program at the Relativistic Heavy Ion Collider. These measurements are important for understanding the Quantum Chromodynamic (QCD) phase diagram. The products of the moments, S\sigma and \kappa\sigma^{2}, are sensitive to the correlation length of the hot and dense medium created in the collisions and are related to the ratios of baryon number susceptibilities of corresponding orders. The products of moments are found to have values significantly below the Skellam expectation and close to expectations based on independent proton and anti-proton production. The measurements are compared to a transport model calculation to understand the effect of acceptance and baryon number conservation, and also to a hadron resonance gas model.

46 data tables

$\Delta N_p$ multiplicity distributions in Au+Au collisions at $\sqrt{S_{NN}}=7.7$ GeV for 0-5 percent, 30-40 percent and 70-80 percent collision centralities at midrapidity.

$\Delta N_p$ multiplicity distributions in Au+Au collisions at $\sqrt{S_{NN}}=11.5$ GeV for 0-5 percent, 30-40 percent and 70-80 percent collision centralities at midrapidity.

$\Delta N_p$ multiplicity distributions in Au+Au collisions at $\sqrt{S_{NN}}=19.6$ GeV for 0-5 percent, 30-40 percent and 70-80 percent collision centralities at midrapidity.

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Neutral pion cross section and spin asymmetries at intermediate pseudorapidity in polarized proton collisions at $\sqrt{s} = 200$ GeV

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.D 89 (2014) 012001, 2014.
Inspire Record 1253360 DOI 10.17182/hepdata.103061

The differential cross section and spin asymmetries for neutral pions produced within the intermediate pseudorapidity range 0.8 < {\eta} < 2.0 in polarized proton-proton collisions at sqrt{s} = 200 GeV are presented. Neutral pions were detected using the endcap electromagnetic calorimeter in the STAR detector at RHIC. The cross section was measured over a transverse momentum range of 5 < p_T < 16 GeV/c and is found to be within the scale uncertainty of a next-to-leading order perturbative QCD calculation. The longitudinal double-spin asymmetry, A_LL, is measured in the same pseudorapidity range. This quantity is sensitive to the gluonic contribution to the proton spin, {\Delta}g(x), at low Bjorken-x (down to x approx 0.01), where it is less constrained by measurements at central pseudorapidity. The measured A_LL is consistent with model predictions. The parity-violating asymmetry, A_L, is also measured and found to be consistent with zero. The transverse single-spin asymmetry, A_N, is measured within a previously unexplored kinematic range in Feynman-x and p_T. Such measurements may aid our understanding of the on-set and kinematic dependence of the large asymmetries observed at more forward pseudorapidity ({\eta} approx 3) and their underlying mechanisms. The A_N results presented are consistent with a twist-3 model prediction of a small asymmetry within the present kinematic range.

16 data tables

Distributions of x1 and x2 in two different bins of reconstructed $\pi^{0}$ pT for events at $\sqrt{s}$ = 200 GeV over 0.8 < $\eta$ < 2.

Comparison of data to Monte Carlo for the distributions of two-photon invariant mass (left) and energy for the higher (center) and lower (right) energy photon.

Comparison of data to Monte Carlo for the distributions of two-photon invariant mass (left) and energy for the higher (center) and lower (right) energy photon.

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Measurement of Charge Multiplicity Asymmetry Correlations in High Energy Nucleus-Nucleus Collisions at 200 GeV

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.C 89 (2014) 044908, 2014.
Inspire Record 1222542 DOI 10.17182/hepdata.100169

A study is reported of the same- and opposite-sign charge-dependent azimuthal correlations with respect to the event plane in Au+Au collisions at 200 GeV. The charge multiplicity asymmetries between the up/down and left/right hemispheres relative to the event plane are utilized. The contributions from statistical fluctuations and detector effects were subtracted from the (co-)variance of the observed charge multiplicity asymmetries. In the mid- to most-central collisions, the same- (opposite-) sign pairs are preferentially emitted in back-to-back (aligned on the same-side) directions. The charge separation across the event plane, measured by the difference, $\Delta$, between the like- and unlike-sign up/down $-$ left/right correlations, is largest near the event plane. The difference is found to be proportional to the event-by-event final-state particle ellipticity (via the observed second-order harmonic $v^{\rm obs}_{2}$), where $\Delta=(1.3\pm1.4({\rm stat})^{+4.0}_{-1.0}({\rm syst}))\times10^{-5}+(3.2\pm0.2({\rm stat})^{+0.4}_{-0.3}({\rm syst}))\times10^{-3}v^{\rm obs}_{2}$ for 20-40% Au+Au collisions. The implications for the proposed chiral magnetic effect are discussed.

43 data tables

Centrality dependences of the charge asymmetry dynamical correlations, $\delta\langle A^{2}\rangle$, and the positive and negative charge asymmetry correlations, $\delta\langle A_{+}A_{-}\rangle$. The asymmetries are calculated between hemispheres separated by the event plane (UD) and between those separated by the plane perpendicular to the event plane (LR). The asymmetry correlations are multiplied by the number of participants $N_{part}$. The upper (lower) shaded band shows half of the systematic uncertainty in the $\delta\langle A_{+}A_{-}\rangle$ ($\delta\langle A^{2}\rangle$); the larger of the UD\ and LR\ systematic uncertainties is drawn. The stars and triangles depict the $d$+Au results.

The correlation differences $\Delta\langle A^{2}\rangle=\delta\langle A^{2}_{ UD}\rangle-\delta\langle A^{2}_{ LR}\rangle$ and $\Delta\langle A_{+}A_{-}\rangle=\delta\langle A_{+}A_{-}\rangle_{ UD}-\delta\langle A_{+}A_{-}\rangle_{ LR}$, scaled by the number of participants $N_{part}$, as a function of $N_{part}$. The error bars are statistical, and the systematic uncertainties are shown in the shaded bands (upper band for $\Delta\langle A_{+}A_{-}\rangle$ and lower band for $\Delta\langle A^{2}\rangle$). Also shown as the lines are the linear-extrapolated values of $\Delta\langle A^{2}\rangle$ and $\Delta\langle A_{+}A_{-}\rangle$ corresponding to a perfect event-plane resolution. The star and triangle depict the $d$+Au results.

The $p_{T}$ dependence of the charge asymmetry dynamical correlations, $\delta\langle A^{2}\rangle$, and the positive and negative charge asymmetry correlations, $\delta\langle A_{+}A_{-}\rangle$. The data are from 20-40% central Au+Au collisions. The asymmetries are calculated between hemispheres separated by the event plane (UD) and between those separated by the plane perpendicular to the event plane (LR).

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Jet-Hadron Correlations in sqrt{s_{NN}} = 200 GeV Au+Au and p+p Collisions

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.Lett. 112 (2014) 122301, 2014.
Inspire Record 1221099 DOI 10.17182/hepdata.89880

Azimuthal angular correlations of charged hadrons with respect to the axis of a reconstructed (trigger) jet in Au+Au and p+p collisions at $\sqrt{s_{\text{NN}}} = 200 \text{GeV}$ in STAR are presented. The trigger jet population in Au+Au collisions is biased towards jets that have not interacted with the medium, allowing easier matching of jet energies between Au+Au and p+p collisions while enhancing medium effects on the recoil jet. The associated hadron yield of the recoil jet is significantly suppressed at high transverse momentum ($p_{\text{T}}^{\text{assoc}}$) and enhanced at low $p_{\text{T}}^{\text{assoc}}$ in 0-20% central Au+Au collisions compared to p+p collisions, which is indicative of medium-induced parton energy loss in ultrarelativistic heavy-ion collisions.

10 data tables

Jet-hadron correlations after background subtraction. Shown with Gaussian fits to jet peaks and systematic uncertanty bands Au+Au(0.5-1 GeV).

Jet-hadron correlations after background subtraction. Shown with Gaussian fits to jet peaks and systematic uncertanty bands p+p(0.5-1).

Jet-hadron correlations after background subtraction. Shown with Gaussian fits to jet peaks and systematic uncertanty bands Au+Au(4-6 GeV).

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Fluctuations of charge separation perpendicular to the event plane and local parity violation in sqrt(sNN)=200 GeV Au+Au collisions at RHIC

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.C 88 (2013) 064911, 2013.
Inspire Record 1219828 DOI 10.17182/hepdata.98967

Previous experimental results based on data (15 million events) collected by the STAR detector at RHIC suggest event-by-event charge separation fluctuations perpendicular to the event plane in non-central heavy-ion collisions. Here we present the correlator previously used split into its two component parts to reveal correlations parallel and perpendicular to the event plane. The results are from a high statistics 200 GeV Au+Au collisions data set (57 million events) collected by the STAR experiment. We explicitly count units of charge separation from which we find clear evidence for more charge separation fluctuations perpendicular than parallel to the event plane. We also employ a modified correlator to study the possible P-even background in same and opposite charge correlations, and find that the P-even background may largely be explained by momentum conservation and collective motion.

10 data tables

(Color online) $\Delta RMS^{\Delta Q}/\langle RMS^{\Delta Q}\rangle$ versus centrality for Au+Au collisions at $\sqrt{s_{NN}}$= 200 GeV. Not corrected for event plane resolution. Errors are statistical only.

(Color online) $\langle sin(\phi_{\alpha} − \Psi_{1})\rangle$ for positive and negative charges versus centrality for Au+Au collisions at $\sqrt{s_{NN}}$= 200 GeV. Shaded area represents the systematic uncertainty for both charge types obtained by comparing correlations from positive and negative pseudorapidity.

(Color online) Three-point correlator, Eq. 1, measured with $1^{st}$ and $2^{nd}$ harmonic event planes versus centrality for Au+Au collisions at $\sqrt{s_{NN}}$= 200 GeV. Shown with crosses are our previous results from the 2004 RHIC run (Y4) [9, 10]. The Y4 run used a second harmonic event plane. Y4 and Y7 $\Psi_{2}$ results are consistent within statistical errors. Shaded areas for the $2^{nd}$ harmonic points represent the systematic uncertainty of the event plane determination. Systematic uncertainties for the $1^{st}$ harmonic points are negligible compared to the statistical ones shown.

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Freeze-out Dynamics via Charged Kaon Femtoscopy in sqrt(sNN)=200 GeV Central Au+Au Collisions

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.C 88 (2013) 034906, 2013.
Inspire Record 1219133 DOI 10.17182/hepdata.97126

We present measurements of three-dimensional correlation functions of like-sign low transverse momentum kaon pairs from sqrt(sNN)=200 GeV Au+Au collisions. A Cartesian surface-spherical harmonic decomposition technique was used to extract the kaon source function. The latter was found to have a three-dimensional Gaussian shape and can be adequately reproduced by Therminator event generator simulations with resonance contributions taken into account. Compared to the pion one, the kaon source function is generally narrower and does not have the long tail along the pair transverse momentum direction. The kaon Gaussian radii display a monotonic decrease with increasing transverse mass m_T over the interval of 0.55<=m_T<=1.15 GeV/c^2. While the kaon radii are adequately described by the m_T-scaling in the outward and sideward directions, in the longitudinal direction the lowest m_T value exceeds the expectations from a pure hydrodynamical model prediction.

4 data tables

Independent correlation moments Rl(q) for orders l = 0,2,4 for midrapidity, low transverse momentum kaon pairs from the 20% most central Au+Au collisions at sqrt(sNN)=200 GeV

Kaon correlation function profiles for midrapidity, low transverse momentum kaon pairs from the 20% most central Au+Au collisions at sqrt(sNN)=200 GeV

Kaon source function profiles extracted from the data

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Observation of an energy-dependent difference in elliptic flow between particles and anti-particles in relativistic heavy ion collisions

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.Lett. 110 (2013) 142301, 2013.
Inspire Record 1210463 DOI 10.17182/hepdata.102939

Elliptic flow ($v_{2}$) values for identified particles at mid-rapidity in Au+Au collisions, measured by the STAR experiment in the Beam Energy Scan at RHIC at $\sqrt{s_{NN}}=$ 7.7--62.4 GeV, are presented. A beam-energy dependent difference of the values of $v_{2}$ between particles and corresponding anti-particles was observed. The difference increases with decreasing beam energy and is larger for baryons compared to mesons. This implies that, at lower energies, particles and anti-particles are not consistent with the universal number-of-constituent-quark (NCQ) scaling of $v_{2}$ that was observed at $\sqrt{s_{NN}}=$ 200 GeV.

99 data tables

The elliptic flow $v_{2}$ of protons and anti-protons as a function of the transverse momentum, $p_{T}$, for 0–80$\%$ central Au+Au collisions. The lower panels show the difference in $v_{2}(p_{T})$ between the particles and anti-particles. The solid curves are fits with a horizontal line. The shaded areas depict the magnitude of the systematic errors.

The elliptic flow $v_{2}$ of protons and anti-protons as a function of the transverse momentum, $p_{T}$, for 0–80$\%$ central Au+Au collisions. The lower panels show the difference in $v_{2}(p_{T})$ between the particles and anti-particles. The solid curves are fits with a horizontal line. The shaded areas depict the magnitude of the systematic errors.

The elliptic flow $v_{2}$ of protons and anti-protons as a function of the transverse momentum, $p_{T}$, for 0–80$\%$ central Au+Au collisions. The lower panels show the difference in $v_{2}(p_{T})$ between the particles and anti-particles. The solid curves are fits with a horizontal line. The shaded areas depict the magnitude of the systematic errors.

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System Size Dependence of Transverse Momentum Correlations at RHIC

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.C 87 (2013) 064902, 2013.
Inspire Record 1216565 DOI 10.17182/hepdata.103060

We present a study of the average transverse momentum ($p_t$) fluctuations and $p_t$ correlations for charged particles produced in Cu+Cu collisions at midrapidity for $\sqrt{s_{NN}} =$ 62.4 and 200 GeV. These results are compared with those published for Au+Au collisions at the same energies, to explore the system size dependence. In addition to the collision energy and system size dependence, the $p_t$ correlation results have been studied as functions of the collision centralities, the ranges in $p_t$, the pseudorapidity $\eta$, and the azimuthal angle $\phi$. The square root of the measured $p_t$ correlations when scaled by mean $p_t$ is found to be independent of both colliding beam energy and system size studied. Transport-based model calculations are found to have a better quantitative agreement with the measurements compared to models which incorporate only jetlike correlations.

17 data tables

Event-by-event $\langle p_{t}\rangle$ distributions for data and mixed events in central Cu+Cu collisions at $\sqrt{s_{NN}}$ = 200 and 62.4 GeV.

Comparison of dynamical $\langle p_{t}\rangle$ fluctuations in Au+Au and Cu+Cu collisions at $\sqrt{s_{NN}}$ = 62.4 and 200 GeV as a function of the number of participanting nucleons.

Comparison of dynamical $\langle p_{t}\rangle$ fluctuations in Au+Au and Cu+Cu collisions at $\sqrt{s_{NN}}$ = 62.4 and 200 GeV as a function of the number of participanting nucleons.

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Third Harmonic Flow of Charged Particles in Au+Au Collisions at sqrtsNN = 200 GeV

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.C 88 (2013) 014904, 2013.
Inspire Record 1210062 DOI 10.17182/hepdata.96234

We report measurements of the third harmonic coefficient of the azimuthal anisotropy, v_3, known as triangular flow. The analysis is for charged particles in Au+Au collisions at sqrtsNN = 200 GeV, based on data from the STAR experiment at the Relativistic Heavy Ion Collider. Two-particle correlations as a function of their pseudorapidity separation are fit with narrow and wide Gaussians. Measurements of triangular flow are extracted from the wide Gaussian, from two-particle cumulants with a pseudorapidity gap, and also from event plane analysis methods with a large pseudorapidity gap between the particles and the event plane. These results are reported as a function of transverse momentum and centrality. A large dependence on the pseudorapidity gap is found. Results are compared with other experiments and model calculations.

28 data tables

Gaussian Width (W) as a function of transverse momentum for most central (0-5%) and mid-central (30-40%) Au+Au collision at sqrt(snn)=200 GEV.

Amplitude (A) as a function of transverse momentum for most central (0-5%) and mid-central (30-40%) Au+Au collision at sqrt(snn)=200 GEV.

Gaussian Width (W) as a function of centrality for Like Sign (LS) and Charge Independent (CI) particles for Au+Au collision at sqrt(snn)=200 GEV.

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Elliptic flow of identified hadrons in Au+Au collisions at $\sqrt{s_{NN}}=$ 7.7--62.4 GeV

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.C 88 (2013) 014902, 2013.
Inspire Record 1210464 DOI 10.17182/hepdata.102408

Measurements of the elliptic flow, $v_{2}$, of identified hadrons ($\pi^{\pm}$, $K^{\pm}$, $K_{s}^{0}$, $p$, $\bar{p}$, $\phi$, $\Lambda$, $\bar{\Lambda}$, $\Xi^{-}$, $\bar{\Xi}^{+}$, $\Omega^{-}$, $\bar{\Omega}^{+}$) in Au+Au collisions at $\sqrt{s_{NN}}=$ 7.7, 11.5, 19.6, 27, 39 and 62.4 GeV are presented. The measurements were done at mid-rapidity using the Time Projection Chamber and the Time-of-Flight detectors of the STAR experiment during the Beam Energy Scan program at RHIC. A significant difference in the $v_{2}$ values for particles and the corresponding anti-particles was observed at all transverse momenta for the first time. The difference increases with decreasing center-of-mass energy, $\sqrt{s_{NN}}$ (or increasing baryon chemical potential, $\mu_{B}$) and is larger for the baryons as compared to the mesons. This implies that particles and anti-particles are no longer consistent with the universal number-of-constituent quark (NCQ) scaling of $v_{2}$ that was observed at $\sqrt{s_{NN}}=$ 200 GeV. However, for the group of particles NCQ scaling at $(m_{T}-m_{0})/n_{q}>$ 0.4 GeV/$c^{2}$ is not violated within $\pm$10%. The $v_{2}$ values for $\phi$ mesons at 7.7 and 11.5 GeV are approximately two standard deviations from the trend defined by the other hadrons at the highest measured $p_{T}$ values.

342 data tables

The elliptic flow,v_2, as a function of the transverse momentum,p_T, from 0–80% central Au+Au collisions for various particle species and energies.

The elliptic flow,v_2, as a function of the transverse momentum,p_T, from 0–80% central Au+Au collisions for various particle species and energies.

The elliptic flow,v_2, as a function of the transverse momentum,p_T, from 0–80% central Au+Au collisions for various particle species and energies.

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Measurement of J/{psi} Azimuthal Anisotropy in Au+Au Collisions at {sqrt{s_{NN}}} = 200 GeV

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.Lett. 111 (2013) 052301, 2013.
Inspire Record 1207322 DOI 10.17182/hepdata.98574

The measurement of J/{psi} azimuthal anisotropy is presented as a function of transverse momentum for different centralities in Au+Au collisions at {sqrt{s_{NN}}} = 200 GeV. The measured J/{psi} elliptic flow is consistent with zero within errors for transverse momentum between 2 and 10 GeV/c. Our measurement suggests that J/{psi} with relatively large transverse momentum are not dominantly produced by coalescence from thermalized charm quarks, when comparing to model calculations.

2 data tables

J/Psi azimuthal anisotropy v2 vs pT measured via the dielectron channel in 0-10%, 10-40%, and 40-80% central Au+Au collisions at 200 GeV. The brackets represent systematic errors. The boxes show the estimated maximum possible range of v2 if the nonflow influence is corrected. The mean pT in each bin for v2 calculation is drawn, but is shifted a little for some centralities so that all points can be seen clearly.

J/Psi azimuthal anisotropy v2 vs pT measured via the dielectron channel in 0-80% central Au+Au collisions at 200 GeV. The brackets represent systematic errors. The boxes show the estimated maximum possible range of v2 if the nonflow influence is corrected.


Studies of di-jets in Au+Au collisions using angular correlations with respect to back-to-back leading hadrons

The STAR collaboration Adamczyk, L. ; Agakishiev, G. ; Aggarwal, M.M. ; et al.
Phys.Rev.C 87 (2013) 044903, 2013.
Inspire Record 1206352 DOI 10.17182/hepdata.103059

Jet-medium interactions are studied via a multi-hadron correlation technique (called "2+1"), where a pair of back-to-back hadron triggers with large transverse momentum is used as a proxy for a di-jet. This work extends the previous analysis for nearly-symmetric trigger pairs with the highest momentum threshold of trigger hadron of 5 GeV/$c$ with the new calorimeter-based triggers with energy thresholds of up to 10 GeV and above. The distributions of associated hadrons are studied in terms of correlation shapes and per-trigger yields on each trigger side. In contrast with di-hadron correlation results with single triggers, the associated hadron distributions for back-to-back triggers from central Au+Au data at $\sqrt{s_{NN}}$=200 GeV show no strong modifications compared to d+Au data at the same energy. An imbalance in the total transverse momentum between hadrons attributed to the near-side and away-side of jet-like peaks is observed. The relative imbalance in the Au+Au measurement with respect to d+Au reference is found to increase with the asymmetry of the trigger pair, consistent with expectation from medium-induced energy loss effects. In addition, this relative total transverse momentum imbalance is found to decrease for softer associated hadrons. Such evolution indicates the energy missing at higher associated momenta is converted into softer hadrons.

8 data tables

Projections of 2-D correlation functions on $\Delta \phi$ (a) (with $|\Delta \eta|$ < 1.0) and $\Delta \eta$ (b) (with $|\Delta \phi|$ < 0.7) for the hadrons associated with their respective triggers (T1 for near-side, T2 for away–side) are shown for d+Au (circles) and central 0-20% Au+Au (squares).

Projections of 2-D correlation functions on $\Delta \phi$ (a) (with $|\Delta \eta|$ < 1.0) and $\Delta \eta$ (b) (with $|\Delta \phi|$ < 0.7) for the hadrons associated with their respective triggers (T1 for near-side, T2 for away–side) are shown for d+Au (circles) and central 0-20% Au+Au (squares).

Projections of 2-D correlation functions on $\Delta \phi$ (a) (with $|\Delta \eta|$ < 1.0) and $\Delta \eta$ (b) (with $|\Delta \phi|$ < 0.7) for the hadrons associated with their respective triggers (T1 for near-side, T2 for away–side) are shown for d+Au (circles) and central 0-20% Au+Au (squares).

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J/$\psi$ production at high transverse momenta in p+p and Au+Au collisions at sqrt(s_{NN}) = 200 GeV

The STAR collaboration Adamczyk, L. ; Agakishiev, G. ; Aggarwal, M.M. ; et al.
Phys.Lett.B 722 (2013) 55-62, 2013.
Inspire Record 1127499 DOI 10.17182/hepdata.98623

We report $J/\psi$ spectra for transverse momenta $p_T$> 5 GeV/$c$ at mid-rapidity in p+p and Au+Au collisions at sqrt(s_{NN}) = 200 GeV.The inclusive $J/\psi$ spectrum and the extracted $B$-hadron feed-down are compared to models incorporating different production mechanisms. We observe significant suppression of the $J/\psi$ yields for $p_T$> 5 GeV/$c$ in 0-30% Au+Au collisions relative to the p+p yield scaled by the number of binary nucleon-nucleon collisions in Au+Au collisions. In 30-60% collisions, no such suppression is observed.The level of suppression is consistently less than that of high-$p_T$ $\pi^{\pm}$ and low-$p_T$ $J/\psi$.

5 data tables

(Color online.) The invariant $J/\psi$ cross section versus $p_{T}$ in p+p collisions at $\sqrt{s}$ = 200 GeV. The vertical bars and boxes depict the statistical and systematic uncertainties, respectively. Also shown are results published by STAR [15] and PHENIX [20]. The curves show theoretical calculations described in the text.

(Color online.) The fraction of $B \rightarrow J/\psi$ over the inclusive $J/\psi$ yield in $p+p$ collisions. The FONLL+CEM model calculation is also shown.

$J/\psi$ $p_{T}$ distributions in Au+Au collisions with different centralities at $\sqrt{s_{NN}}$ = 200 GeV. For clarity, the data and curves have been scaled as indicated in the legends. The PHENIX results are reported in [6]. The curves are model fits described in the text.

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Inclusive charged hadron elliptic flow in Au + Au collisions at $\sqrt{s_{NN}}$ = 7.7 - 39 GeV

The STAR collaboration Adamczyk, L. ; Agakishiev, G. ; Aggarwal, M.M. ; et al.
Phys.Rev.C 86 (2012) 054908, 2012.
Inspire Record 1119620 DOI 10.17182/hepdata.102951

A systematic study is presented for centrality, transverse momentum ($p_T$) and pseudorapidity ($\eta$) dependence of the inclusive charged hadron elliptic flow ($v_2$) at midrapidity($|\eta| < 1.0$) in Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7, 11.5, 19.6, 27 and 39 GeV. The results obtained with different methods, including correlations with the event plane reconstructed in a region separated by a large pseudorapidity gap and 4-particle cumulants ($v_2{4}$), are presented in order to investigate non-flow correlations and $v_2$ fluctuations. We observe that the difference between $v_2{2}$ and $v_2{4}$ is smaller at the lower collision energies. Values of $v_2$, scaled by the initial coordinate space eccentricity, $v_{2}/\varepsilon$, as a function of $p_T$ are larger in more central collisions, suggesting stronger collective flow develops in more central collisions, similar to the results at higher collision energies. These results are compared to measurements at higher energies at the Relativistic Heavy Ion Collider ($\sqrt{s_{NN}}$ = 62.4 and 200 GeV) and at the Large Hadron Collider (Pb + Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV). The $v_2(p_T)$ values for fixed $p_T$ rise with increasing collision energy within the $p_T$ range studied ($< 2 {\rm GeV}/c$). A comparison to viscous hydrodynamic simulations is made to potentially help understand the energy dependence of $v_{2}(p_{T})$. We also compare the $v_2$ results to UrQMD and AMPT transport model calculations, and physics implications on the dominance of partonic versus hadronic phases in the system created at Beam Energy Scan (BES) energies are discussed.

12 data tables

The event plane resolutions for Au + Au collisions at $\sqrt{s_{NN}}$ = 7.7, 11.5, 19.6, 27 and 39 GeV as a function of collision centrality.

The comparison of $v_2$ as a function of $p_T$ between GF-cumulant and Q-cumulant methods in Au+Au collisions at $\sqrt{s_{NN}}$ = 39 GeV.

The $p_T$ (> 0.2 GeV/c) and $\eta$ ($∣\eta∣$ < 1) integrated $v_2$ as a function of collision centrality for Au + Au collisions at $\sqrt{s_{NN}}$ = 7.7 GeV, 11.5 GeV, 19.6 GeV, 27 GeV and 39 GeV.

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Single Spin Asymmetry $A_N$ in Polarized Proton-Proton Elastic Scattering at $\sqrt{s}=200$ GeV

The STAR collaboration Adamczyk, L. ; Agakishiev, G. ; Aggarwal, M.M. ; et al.
Phys.Lett.B 719 (2013) 62-69, 2013.
Inspire Record 1117881 DOI 10.17182/hepdata.102952

We report a high precision measurement of the transverse single spin asymmetry $A_N$ at the center of mass energy $\sqrt{s}=200$ GeV in elastic proton-proton scattering by the STAR experiment at RHIC. The $A_N$ was measured in the four-momentum transfer squared $t$ range $0.003 \leqslant |t| \leqslant 0.035$ $\GeVcSq$, the region of a significant interference between the electromagnetic and hadronic scattering amplitudes. The measured values of $A_N$ and its $t$-dependence are consistent with a vanishing hadronic spin-flip amplitude, thus providing strong constraints on the ratio of the single spin-flip to the non-flip amplitudes. Since the hadronic amplitude is dominated by the Pomeron amplitude at this $\sqrt{s}$, we conclude that this measurement addresses the question about the presence of a hadronic spin flip due to the Pomeron exchange in polarized proton-proton elastic scattering.

3 data tables

The asymmetry $\varepsilon(\varphi)/(P_B + P_Y)$ for various $t$-intervals.

The measured single spin asymmetry $A_N$ for five $-t$ intervals.

Fitted value of $r_5$.


Longitudinal and transverse spin asymmetries for inclusive jet production at mid-rapidity in polarized p+p collisions at sqrt{s}=200 GeV

The STAR collaboration Adamczyk, L. ; Agakishiev, G. ; Aggarwal, M.M. ; et al.
Phys.Rev.D 86 (2012) 032006, 2012.
Inspire Record 1114529 DOI 10.17182/hepdata.98966

We report STAR measurements of the longitudinal double-spin asymmetry A_LL, the transverse single-spin asymmetry A_N, and the transverse double-spin asymmetries A_Sigma and A_TT for inclusive jet production at mid-rapidity in polarized p+p collisions at a center-of-mass energy of sqrt{s} = 200 GeV. The data represent integrated luminosities of 7.6 /pb with longitudinal polarization and 1.8 /pb with transverse polarization, with 50-55% beam polarization, and were recorded in 2005 and 2006. No evidence is found for the existence of statistically significant jet A_N, A_Sigma, or A_TT at mid-rapidity. Recent model calculations indicate the A_N results may provide new limits on the gluon Sivers distribution in the proton. The asymmetry A_LL significantly improves the knowledge of gluon polarization in the nucleon.

8 data tables

(color online) $A_{N}$ as a function of the corrected mean $p_{T}$ for 2006 transverse data. The panels present $A_{N}$ for four different $\eta$ bins. $A_{N}$ is the left-right single-spin asymmetry for a transversely polarized beam. The errors shown combine the statistical uncertainties, which dominate, with all systematic uncertainties except trigger and reconstruction bias. See Sect. V A for a discussion of the latter.

(color online) $A_{N}$ as a function of the corrected mean $p_{T}$ for 2006 transverse data. The panels present $A_{N}$ for four different $\eta$ bins. $A_{N}$ is the left-right single-spin asymmetry for a transversely polarized beam. The errors shown combine the statistical uncertainties, which dominate, with all systematic uncertainties except trigger and reconstruction bias. See Sect. V A for a discussion of the latter.

(color online) $A_{N}$ as a function of the corrected mean $p_{T}$ for 2006 transverse data. The panels present $A_{N}$ for four different $\eta$ bins. $A_{N}$ is the left-right single-spin asymmetry for a transversely polarized beam. The errors shown combine the statistical uncertainties, which dominate, with all systematic uncertainties except trigger and reconstruction bias. See Sect. V A for a discussion of the latter.

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Transverse Single-Spin Asymmetry and Cross-Section for pi0 and eta Mesons at Large Feynman-x in Polarized p+p Collisions at sqrt(s)=200 GeV

The STAR collaboration Adamczyk, L. ; Agakishiev, G. ; Aggarwal, M.M. ; et al.
Phys.Rev.D 86 (2012) 051101, 2012.
Inspire Record 1116643 DOI 10.17182/hepdata.101343

Measurements of the differential cross-section and the transverse single-spin asymmetry, A_N, vs. x_F for pi0 and eta mesons are reported for 0.4 < x_F < 0.75 at an average pseudorapidity of 3.68. A data sample of approximately 6.3 pb^{-1} was analyzed, which was recorded during p+p collisions at sqrt{s} = 200 GeV by the STAR experiment at RHIC. The average transverse beam polarization was 56%. The cross-section for pi0 is consistent with a perturbative QCD prediction, and the eta/pi0 cross-section ratio agrees with previous mid-rapidity measurements. For 0.55 < x_F < 0.75, A_N for eta (0.210 +- 0.056) is 2.2 standard deviations larger than A_N for pi0 (0.081 +- 0.016).

4 data tables

(c) $A_N$ vs. $M_{\gamma\gamma}$ for the above mass distribution. The error bars are statistical uncertainties only.

Differential production cross-sections for $\pi^0$ and $\eta$ at average pseudorapidity of 3.68. Also shown are the previously published STAR results for similar kinematics [21] and a NLO pQCD calculation of the π0 cross-section [32]. The error band represents the uncertainty in the calculation due to scale variations.

The $\eta$ to $\pi^0$ cross-section ratio is shown in the bottom panel. The error bars indicate the total statistical and systematic uncertainties.

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Measurements of $D^{0}$ and $D^{*}$ Production in $p$ + $p$ Collisions at $\sqrt{s}$ = 200 GeV

The STAR collaboration Adamczyk, L. ; Agakishiev, G. ; Aggarwal, M.M. ; et al.
Phys.Rev.D 86 (2012) 072013, 2012.
Inspire Record 1111571 DOI 10.17182/hepdata.101344

We report measurements of charmed-hadron ($D^{0}$, $D^{*}$) production cross sections at mid-rapidity in $p$ + $p$ collisions at a center-of-mass energy of 200 GeV by the STAR experiment. Charmed hadrons were reconstructed via the hadronic decays $D^{0}\rightarrow K^{-}\pi^{+}$, $D^{*+}\rightarrow D^{0}\pi^{+}\rightarrow K^{-}\pi^{+}\pi^{+}$ and their charge conjugates, covering the $p_T$ range of 0.6$-$2.0 GeV/$c$ and 2.0$-$6.0 GeV/$c$ for $D^{0}$ and $D^{*+}$, respectively. From this analysis, the charm-pair production cross section at mid-rapidity is $d\sigma/dy|_{y=0}^{c\bar{c}}$ = 170 $\pm$ 45 (stat.) $^{+38}_{-59}$ (sys.) $\mu$b. The extracted charm-pair cross section is compared to perturbative QCD calculations. The transverse momentum differential cross section is found to be consistent with the upper bound of a Fixed-Order Next-to-Leading Logarithm calculation.

1 data table

$c\bar{c}$ production cross section as inferred from D$^0$ and D$^\star$ production in p+p collisions at $\sqrt{s} = 200$ GeV at $|\eta| < 1$ compared with FONLL calculations. The D$^0$ and D$^\star$ data points were divided by the charm quark fragmentation ratios 0.565 ($c \rightarrow$ D$^0$) and 0.224 ($c \rightarrow$ D$^{\star +}$) [34], respectively, to convert to the $c\bar{c}$ production cross section.


Di-electron spectrum at mid-rapidity in $p+p$ collisions at $\sqrt{s} = 200$ GeV

The STAR collaboration Adamczyk, L. ; Agakishiev, G. ; Aggarwal, M.M. ; et al.
Phys.Rev.C 86 (2012) 024906, 2012.
Inspire Record 1107765 DOI 10.17182/hepdata.116553

We report on mid-rapidity mass spectrum of di-electrons and cross sections of pseudoscalar and vector mesons via $e^{+}e^{-}$ decays, from $\sqrt{s} = 200$ GeV $p+p$ collisions, measured by the large acceptance experiment STAR at RHIC. The ratio of the di-electron continuum to the combinatorial background is larger than 10% over the entire mass range. Simulations of di-electrons from light-meson decays and heavy-flavor decays (charmonium and open charm correlation) are found to describe the data. The extracted $\omega\rightarrow e^{+}e^{-}$ invariant yields are consistent with previous measurements. The mid-rapidity yields ($dN/dy$) of $\phi$ and $J/\psi$ are extracted through their di-electron decay channels and are consistent with the previous measurements of $\phi\rightarrow K^{+}K^{-}$ and $J/\psi\rightarrow e^{+}e^{-}$. Our results suggest a new upper limit of the branching ratio of the $\eta \rightarrow e^{+}e^{-}$ of $1.7\times10^{-5}$ at 90% confidence level.

16 data tables

The electron-pair invariant mass distri- butions for unlike-sign pairs in minimum-bias p + p collisions.

The electron-pair invariant mass distributions for like-sign pairs in minimum-bias p + p collisions.

The electron-pair invariant mass distributions for mix-event pairs in minimum-bias p + p collisions.

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Measurement of the $W \to e \nu$ and $Z/\gamma^* \to e^+e^-$ Production Cross Sections at Mid-rapidity in Proton-Proton Collisions at $\sqrt{s}$ = 500 GeV

The STAR collaboration Adamczyk, L. ; Agakishiev, G. ; Aggarwal, M.M. ; et al.
Phys.Rev.D 85 (2012) 092010, 2012.
Inspire Record 1081120 DOI 10.17182/hepdata.98931

We report measurements of the charge-separated $W^{+(-)} \to e^{+(-)} + \nu_e(\bar{\nu}_e)$ and $Z/\gamma^* \to e^+e^-$ production cross sections at mid-rapidity in proton-proton collisions at $\sqrt{s}$ = 500 GeV. These results are based on 13.2 pb$^{-1}$ of data recorded in 2009 by the STAR detector at RHIC. Production cross sections for W bosons that decay via the $e \nu$ channel were measured to be $\sigma(pp \to W^+ X) \cdot BR(W^+ \to e^+ \nu_e)$ = 117.3 \pm 5.9(stat) \pm 6.2(syst) \pm 15.2(lumi) pb, and $\sigma(pp \to W^- X) \cdot BR(W^- \to e^- \bar{\nu}_e)$ = 43.3 \pm 4.6(stat) \pm 3.4(syst) \pm 5.6(lumi) pb. For $Z/\gamma^*$ production, $\sigma(pp \to Z/\gamma^* X) \cdot BR(Z/\gamma^* \to e^+ e^-)$ = 7.7 \pm 2.1(stat) $^{+0.5}_{-0.9}$(syst) \pm 1.0(lumi) pb for di-lepton invariant masses $m_{e^+e^-}$ between 70 and 110 GeV/$c^2$. First measurements of the W cross section ratio, $\sigma(pp \to W^+ X) / \sigma(pp \to W^- X)$, at $\sqrt{s}$ = 500 GeV are also reported. Theoretical predictions, calculated using recent parton distribution functions, are found to agree with the measured cross sections.

11 data tables

(Color online) Trigger rate as a function of vernier scan beam displacement in the x and y directions. The transverse beam widths ($\sigma_{x}$ and $\sigma_{y}$) and maximum trigger rate ($R^{max}_{ver}$) were extracted from the fit, which is superimposed.

(Color online) Trigger rate as a function of vernier scan beam displacement in the x and y directions. The transverse beam widths ($\sigma_{x}$ and $\sigma_{y}$) and maximum trigger rate ($R^{max}_{ver}$) were extracted from the fit, which is superimposed.

(Color online) Distributions of $E^{e}_{T}$ for W candidate events after sequentially applying the selection criteria de- scribed in Secs. IV A and IV B.

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Directed Flow of Identified Particles in Au + Au Collisions at $\sqrtsNN = 200$ GeV at RHIC

The STAR collaboration Adamczyk, L. ; Agakishiev, G. ; Aggarwal, M.M. ; et al.
Phys.Rev.Lett. 108 (2012) 202301, 2012.
Inspire Record 1081744 DOI 10.17182/hepdata.96905

STAR's measurements of directed flow ($v_1$) around midrapidity for $\pi^{\pm}$, K$^{\pm}$, K$_S^0$, $p$ and $\bar{p}$ in Au + Au collisions at $\sqrtsNN = 200$ GeV are presented. A negative $v_1(y)$ slope is observed for most of produced particles ($\pi^{\pm}$, K$^{\pm}$, K$_{S}^{0}$ and $\bar{p}$). In 5-30% central collisions a sizable difference is present between the $v_1(y)$ slope of protons and antiprotons, with the former being consistent with zero within errors. The $v_1$ excitation function is presented. Comparisons to model calculations (RQMD, UrQMD, AMPT, QGSM with parton recombination, and a hydrodynamics model with a tilted source) are made. For those models which have calculations of $v_1$ for both pions and protons, none of them can describe $v_1(y)$ for pions and protons simultaneously. The hydrodynamics model with a tilted source as currently implemented cannot explain the centrality dependence of the difference between the $v_1(y)$ slopes of protons and antiprotons.

6 data tables

$v_1$ for $\pi^{\pm}$, $K^{\pm}$, $K_{S}^{0}$ (left panel), p and $\bar{p}$ (right panel) as a function of rapidity for 10-70$\%$ $Au + Au$ collisions at $\sqrt{s_{NN}} = 200$ GeV. The lines present the linear fit to the $\pi^{\pm}$, $K^{\pm}$, $K_{S}^{0}$, p and $\bar{p}$’s $v_1$(y) respectively. Data points around $y = 0.29$ are slightly shifted horizontally to avoid overlapping.

$v_1$ for $\pi^{\pm}$, $K^{\pm}$, $K_{S}^{0}$ (left panel), p and $\bar{p}$ (right panel) as a function of rapidity for 10-70$\%$ $Au + Au$ collisions at $\sqrt{s_{NN}} = 200$ GeV. The lines present the linear fit to the $\pi^{\pm}$, $K^{\pm}$, $K_{S}^{0}$, p and $\bar{p}$’s $v_1$(y) respectively. Data points around $y = 0.29$ are slightly shifted horizontally to avoid overlapping.

$v_1$ for $\pi^{\pm}$, $K^{\pm}$, $K_{S}^{0}$ (left panel), p and $\bar{p}$ (right panel) as a function of rapidity for 10-70$\%$ $Au + Au$ collisions at $\sqrt{s_{NN}} = 200$ GeV. The lines present the linear fit to the $\pi^{\pm}$, $K^{\pm}$, $K_{S}^{0}$, p and $\bar{p}$’s $v_1$(y) respectively. Data points around $y = 0.29$ are slightly shifted horizontally to avoid overlapping.

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System size and energy dependence of near-side di-hadron correlations

The STAR collaboration Agakishiev, G. ; Aggarwal, M.M. ; Ahammed, Z. ; et al.
Phys.Rev.C 85 (2012) 014903, 2012.
Inspire Record 943192 DOI 10.17182/hepdata.77720

Two-particle azimuthal ($\Delta\phi$) and pseudorapidity ($\Delta\eta$) correlations using a trigger particle with large transverse momentum ($p_T$) in $d$+Au, Cu+Cu and Au+Au collisions at $\sqrt{s_{{NN}}}$ =\xspace 62.4 GeV and 200~GeV from the STAR experiment at RHIC are presented. The \ns correlation is separated into a jet-like component, narrow in both $\Delta\phi$ and $\Delta\eta$, and the ridge, narrow in $\Delta\phi$ but broad in $\Delta\eta$. Both components are studied as a function of collision centrality, and the jet-like correlation is studied as a function of the trigger and associated $p_T$. The behavior of the jet-like component is remarkably consistent for different collision systems, suggesting it is produced by fragmentation. The width of the jet-like correlation is found to increase with the system size. The ridge, previously observed in Au+Au collisions at $\sqrt{s_{{NN}}}$ = 200 GeV, is also found in Cu+Cu collisions and in collisions at $\sqrt{s_{{NN}}}$ =\xspace 62.4 GeV, but is found to be substantially smaller at $\sqrt{s_{{NN}}}$ =\xspace 62.4 GeV than at $\sqrt{s_{{NN}}}$ = 200 GeV for the same average number of participants ($ \langle N_{\mathrm{part}}\rangle$). Measurements of the ridge are compared to models.

40 data tables

Parameterizations of the transverse momentum dependence of the reconstruction efficiency of charged particles in the TPC in various collision systems, energies and centrality bins for the track selection cuts used in this analysis.

The raw correlation in $\Delta\eta$ for di-hadron correlations for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for 0-12% central \Au collisions for $|\Delta\phi|<$ 0.78 before and after the track merging correction is applied. The data have been reflected about $\Delta\eta$=0.

Sample correlations in $\Delta\eta$ ($|\Delta\phi|<$ 0.78) for 3 $<$ $p_T^{trigger}$ $<$ 6 GeV/$c$ and 1.5 GeV/$c$ $<$ $p_T^{associated}$ $<$ $p_T^{trigger}$ for 0-60% Cu+Cu at $\sqrt{s_{NN}}$ = 62.4 GeV, 0-80% Au+Au at $\sqrt{s_{NN}}$ = 62.4 GeV, 0-95% $d$+Au at $\sqrt{s_{NN}}$ = 200 GeV, 0-60% Cu+Cu at $\sqrt{s_{NN}}$ = 200 GeV, 40-80% Au+Au at $\sqrt{s_{NN}}$ = 200 GeV, and 0-12% central Au+Au at $\sqrt{s_{NN}}$ = 200 GeV. The data are averaged between positive and negative $\Delta\eta$. 5% systematic uncertainty due to track reconstruction efficiency not listed below.

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Measurement of Z-pair production in e+ e- collisions and constraints on anomalous neutral gauge couplings

The ALEPH collaboration Schael, S. ; Barate, R. ; Bruneliere, R. ; et al.
JHEP 04 (2009) 124, 2009.
Inspire Record 824816 DOI 10.17182/hepdata.52431

The ZZ production cross section is measured from a data sample corresponding to a total integrated luminosity of 452 pb(-')(1), collected by the ALEPH experiment at LEP at centre-of-mass energies from 192 to 209 GeV. Individual cross sections, ext racted at six centre-of-mass energies, are found to be in agreement with Standard Model calculations. The results are used to set limits on anomalous neutral gauge couplings.

1 data table

Measured E+ E- --> Z0 Z0 cross sections.