Pseudorapidity asymmetry and centrality dependence of charged hadron spectra in d + Au collisions at S(NN)**(1/2) = 200-GeV

The STAR collaboration Adams, J. ; Aggarwal, M.M. ; Ahammed, Z. ; et al.
Phys.Rev.C 70 (2004) 064907, 2004.
Inspire Record 656934 DOI 10.17182/hepdata.102944

The pseudorapidity asymmetry and centrality dependence of charged hadron spectra in d+Au collisions at $\sqrt{s_{NN}}=200$ GeV are presented. The charged particle density at mid-rapidity, its pseudorapidity asymmetry and centrality dependence are reasonably reproduced by a Multi-Phase Transport model, by HIJING, and by the latest calculations in a saturation model. Ratios of transverse momentum spectra between backward and forward pseudorapidity are above unity for \pT below 5 GeV/$c$. The ratio of central to peripheral spectra in d+Au collisions shows enhancement at 2 $<$ \pT $<$ 6 GeV/$c$, with a larger effect at backward rapidity than forward rapidity. Our measurements are in qualitative agreement with gluon saturation and in contrast to calculations based on incoherent multiple partonic scatterings.

0 data tables

Multi-strange baryon elliptic flow in Au + Au collisions at s(NN)**(1/2) = 200-GeV

The STAR collaboration Adams, J. ; Aggarwal, M.M. ; Ahammed, Z. ; et al.
Phys.Rev.Lett. 95 (2005) 122301, 2005.
Inspire Record 681161 DOI 10.17182/hepdata.102945

We report on the first measurement of elliptic flow $v_2(p_T)$ of multi-strange baryons $\Xi+\bar{Xi}$ and $\Omega+\bar{Omega} in heavy-ion collisions. In minimum bias Au+Au collisions at sqrt(s_NN) = 200 GeV, a significant amount of elliptic flow, comparable to other non-strange baryons, is observed for multi-strange baryons which are expected to be particularly sensitive to the dynamics of the partonic stage of heavy-ion collisions. The $p_T$ dependence of $v_2$ of the multi-strange baryons confirms the number of constituent quark scaling previously observed for lighter hadrons. These results support the idea that a substantial fraction of the observed collective motion is developed at the early partonic stage in ultra-relativistic nuclear collisions at RHIC.

0 data tables

Directed flow in Au+Au collisions at s(NN)**(1/2) = 62-GeV

The STAR collaboration Adams, J. ; Aggarwal, M.M. ; Ahammed, Z. ; et al.
Phys.Rev.C 73 (2006) 034903, 2006.
Inspire Record 695404 DOI 10.17182/hepdata.102947

We present the directed flow ($v_1$) measured in Au+Au collisions at $\sqrt{s_{_{NN}}}$ = 62.4 GeV in the mid-pseudorapidity region $|\eta|<1.3$ and in the forward pseudorapidity region $2.5 < |\eta| < 4.0$. The results are obtained using the three-particle cumulant method, the event plane method with mixed harmonics, and for the first time at the Relativistic Heavy Ion Collider (RHIC), the standard method with the event plane reconstructed from spectator neutrons. Results from all three methods are in good agreement. Over the pseudorapidity range studied, charged particle directed flow is in the direction opposite to that of fragmentation neutrons.

0 data tables

Energy and system-size dependence of two- and four-particle $v_2$ measurements in heavy-ion collisions at RHIC and their implications on flow fluctuations and nonflow

The STAR collaboration Agakishiev, G. ; Aggarwal, M.M. ; Ahammed, Z. ; et al.
Phys.Rev.C 86 (2012) 014904, 2012.
Inspire Record 955160 DOI 10.17182/hepdata.101341

We present STAR measurements of azimuthal anisotropy by means of the two- and four-particle cumulants $v_2$ ($v_2\{2\}$ and $v_2\{4\}$) for Au+Au and Cu+Cu collisions at center of mass energies $\sqrt{s_{_{\mathrm{NN}}}} = 62.4$ and 200 GeV. The difference between $v_2\{2\}^2$ and $v_2\{4\}^2$ is related to $v_{2}$ fluctuations ($\sigma_{v_2}$) and nonflow $(\delta_{2})$. We present an upper limit to $\sigma_{v_2}/v_{2}$. Following the assumption that eccentricity fluctuations $\sigma_{\epsilon}$ dominate $v_2$ fluctuations $\frac{\sigma_{v_2}}{v_2} \approx \frac{\sigma_{\epsilon}}{\epsilon}$ we deduce the nonflow implied for several models of eccentricity fluctuations that would be required for consistency with $v_2\{2\}$ and $v_2\{4\}$. We also present results on the ratio of $v_2$ to eccentricity.

0 data tables

Measurement of angular and momentum distributions of charged particles within and around jets in Pb+Pb and $pp$ collisions at $\sqrt{s_{\mathrm{NN}}} = 5.02$ TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abbott, Dale Charles ; et al.
Phys.Rev.C 100 (2019) 064901, 2019.
Inspire Record 1749578 DOI 10.17182/hepdata.91160

Studies of the fragmentation of jets into charged particles in heavy-ion collisions can provide information about the mechanism of jet-quenching by the hot and dense QCD matter created in such collisions, the quark-gluon plasma. This paper presents a measurement of the angular distribution of charged particles around the jet axis in $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV Pb+Pb and $pp$ collisions, using the ATLAS detector at the LHC. The Pb+Pb and $pp$ data sets have integrated luminosities of 0.49 nb$^{-1}$ and 25 pb$^{-1}$, respectively. The measurement is performed for jets reconstructed with the anti-$k_{t}$ algorithm with radius parameter $R = 0.4$ and is extended to an angular distance of $r= 0.8$ from the jet axis. Results are presented as a function of Pb+Pb collision centrality and distance from the jet axis for charged particles with transverse momenta in the 1$-$63 GeV range, matched to jets with transverse momenta in the 126$-$316 GeV range and an absolute value of jet rapidity of less than 1.7. Modifications to the measured distributions are quantified by taking a ratio to the measurements in $pp$ collisions. Yields of charged particles with transverse momenta below 4 GeV are observed to be increasingly enhanced as a function of angular distance from the jet axis, reaching a maximum at $r=0.6$. Charged particles with transverse momenta above 4 GeV have an enhanced yield in Pb+Pb collisions in the jet core for angular distances up to $r = 0.05$ from the jet axis, with a suppression at larger distances.

333 data tables

D(pT,r)_PbPb The charged particle distributions around jets as a function of distance from the jet axis in PbPb collisions at 5.02 TeV for different centrality, track pT and jet pT ranges.

D(pT,r)_PbPb The charged particle distributions around jets as a function of distance from the jet axis in PbPb collisions at 5.02 TeV for different centrality, track pT and jet pT ranges.

D(pT,r)_PbPb The charged particle distributions around jets as a function of distance from the jet axis in PbPb collisions at 5.02 TeV for different centrality, track pT and jet pT ranges.

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Measurement of the $CP$-violating phase $\phi_s$ in $B^0_s \to J/\psi\phi$ decays in ATLAS at 13 TeV

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abbott, Dale Charles ; et al.
CERN-EP-2019-218, 2020.
Inspire Record 1776624 DOI 10.17182/hepdata.103066

A measurement of the $B^0_s \to J/\psi\phi$ decay parameters using 80.5 fb$^{-1}$ of integrated luminosity collected with the ATLAS detector from 13 TeV proton-proton collisions at the LHC is presented. The measured parameters include the $CP$-violating phase $\phi_s$, the width difference $\Delta\Gamma_{s}$ between the $B^0_s$ meson mass eigenstates and the average decay width $\Gamma_{s}$. The values measured for the physical parameters are combined with those from 19.2 fb$^{-1}$ of 7 TeV and 8 TeV data, leading to the following: \begin{eqnarray*} \phi_s & = & -0.087\phantom{0} \pm 0.036\phantom{0} ~\mathrm{(stat.)} \pm 0.021\phantom{0} ~\mathrm{(syst.)~rad} \\ \Delta\Gamma_{s} & = & \phantom{-}0.0657 \pm 0.0043 ~\mathrm{(stat.)} \pm 0.0037 ~\mathrm{(syst.)~ps}^{-1} \\ \Gamma_{s} & = & \phantom{-}0.6703 \pm 0.0014 ~\mathrm{(stat.)} \pm 0.0018 ~\mathrm{(syst.)~ps}^{-1} \\ \end{eqnarray*} Results for $\phi_s$ and $\Delta\Gamma_{s}$ are also presented as 68% confidence level contours in the $\phi_s$-$\Delta\Gamma_{s}$ plane. Furthermore, the transversity amplitudes and corresponding strong phases are measured. $\phi_s$ and $\Delta\Gamma_{s}$ measurements are in agreement with the Standard Model predictions.

8 data tables

Fitted values for the physical parameters of interest with their statistical and systematic uncertainties, for the result of solution (a).

Fitted values for the physical parameters of interest with their statistical and systematic uncertainties, for the result of solution (b).

Fit correlations between the physical parameters of interest, obtained from the fit for solution (a).

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Elliptic flow of electrons from beauty-hadron decays in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
CERN-EP-2020-085, 2020.
Inspire Record 1797450 DOI 10.17182/hepdata.102642

The elliptic flow of electrons from beauty hadron decays at midrapidity ($|y|$ $<$ 0.8) is measured in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV with the ALICE detector at the LHC. The azimuthal distribution of the particles produced in the collisions can be parameterized with a Fourier expansion, in which the second harmonic coefficient represents the elliptic flow, $v_{\rm 2}$. The $v_{\rm 2}$ coefficient is measured for the first time in transverse momentum ($p_{\rm{T}}$) range 1.3-6 GeV/$c$ in the centrality class 30-50%. The measurement of electrons from beauty-hadron decays exploits their larger mean proper decay length $c\tau \approx$ 500 $\mu$m compared to that of charm hadrons and most of the other background sources. The $v_{\rm 2}$ of electrons from beauty hadron decays at midrapidity is found to be positive with a significance of 3.75$\sigma$. The results provide insights on the degree of thermalization of beauty quarks in the medium. A model assuming full thermalization of beauty quarks is strongly disfavoured by the measurement at high $p_{\rm{T}}$, but is in agreement with the results at low $p_{\rm{T}}$. Transport models including substantial interactions of beauty quarks with an expanding strongly-interacting medium describe the measurement.

1 data table

$v_{2}$ of electrons from beauty hadron decays as a function of $p_{\rm T}$ in the centrality range 30-50% for $\sqrt{s_{\rm NN}}=5.02 {\rm~TeV}$


Version 2
Reconstruction and identification of boosted di-$\tau$ systems in a search for Higgs boson pairs using 13 TeV proton-proton collision data in ATLAS

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abbott, Dale Charles ; et al.
JHEP 11 (2020) 163, 2020.
Inspire Record 1809175 DOI 10.17182/hepdata.95432

In this paper, a new technique for reconstructing and identifying hadronically decaying $\tau^+\tau^-$ pairs with a large Lorentz boost, referred to as the di-$\tau$ tagger, is developed and used for the first time in the ATLAS experiment at the Large Hadron Collider. A benchmark di-$\tau$ tagging selection is employed in the search for resonant Higgs boson pair production, where one Higgs boson decays into a boosted $b\bar{b}$ pair and the other into a boosted $\tau^+\tau^-$ pair, with two hadronically decaying $\tau$-leptons in the final state. Using 139 fb$^{-1}$ of proton$-$proton collision data recorded at a centre-of-mass energy of 13 TeV, the efficiency of the di-$\tau$ tagger is determined and the background with quark- or gluon-initiated jets misidentified as di-$\tau$ objects is estimated. The search for a heavy, narrow, scalar resonance produced via gluon$-$gluon fusion and decaying into two Higgs bosons is carried out in the mass range 1$-$3 TeV using the same dataset. No deviations from the Standard Model predictions are observed, and 95% confidence-level exclusion limits are set on this model.

4 data tables

Signal acceptance times selection efficiency as a function of the resonance mass, at various stages of the event selection. From top to bottom: an event pre-selection (trigger, object definitions and $E_{T}^{miss}>10$ GeV) is performed first; the requirements on the di-$\tau$ object and large-$R$ jet detailed in the text are then applied; finally, the $HH$ SR definition must be satisfied.

Distribution of $m^{vis}_{HH}$ after applying all the event selection that define the $HH$ SR, except the requirement on $m^{vis}_{HH}$. The background labelled as "Others" contains $W$+jets, diboson, $t\bar{t}$ and single-top-quark processes. The $X\rightarrow HH \rightarrow b\bar{b}\tau^{+}\tau^{-}$ signal is overlaid for two resonance mass hypotheses with a cross-section set to the expected limit, while all backgrounds are pre-fit. The first and the last bins contains the under-flow and over-flow bin entries, respectively. The hatched bands represent combined statistical and systematic uncertainties.

Event yields of the various estimated backgrounds and data, computed in the signal region of the search for $X\rightarrow HH \rightarrow b\bar{b}\tau^{+}\tau^{-}$. The background labelled as "Others" contains $W$+jets, diboson, $t\bar{t}$ and single-top-quark processes. Statistical and systematic uncertainties are quoted. The background yields and uncertainties are pre-fit and are found to be similar to those post-fit.

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Version 2
Search for diboson resonances in hadronic final states in 139 fb$^{-1}$ of $pp$ collisions at $\sqrt{s} = 13$ TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abbott, Dale Charles ; et al.
JHEP 09 (2019) 091, 2019.
Inspire Record 1740685 DOI 10.17182/hepdata.91052

Narrow resonances decaying into $WW$, $WZ$ or $ZZ$ boson pairs are searched for in 139 fb$^{-1}$ of proton-proton collision data at a centre-of-mass energy of $\sqrt{s}=13$ TeV recorded with the ATLAS detector at the Large Hadron Collider from 2015 to 2018. The diboson system is reconstructed using pairs of high transverse momentum, large-radius jets. These jets are built from a combination of calorimeter- and tracker-inputs compatible with the hadronic decay of a boosted $W$ or $Z$ boson, using jet mass and substructure properties. The search is performed for diboson resonances with masses greater than 1.3 TeV. No significant deviations from the background expectations are observed. Exclusion limits at the 95% confidence level are set on the production cross-section times branching ratio into dibosons for resonances in a range of theories beyond the Standard Model, with the highest excluded mass of a new gauge boson at 3.8 TeV in the context of mass-degenerate resonances that couple predominantly to gauge bosons.

1 data table

RS Graviton ZZ Acceptance times Efficiency


Version 2
Global polarization measurement in Au+Au collisions

The STAR collaboration Abelev, B.I. ; Aggarwal, M.M. ; Ahammed, Z. ; et al.
Phys.Rev.C 76 (2007) 024915, 2007.
Inspire Record 750410 DOI 10.17182/hepdata.98581

The system created in non-central relativistic nucleus-nucleus collisions possesses large orbital angular momentum. Due to spin-orbit coupling, particles produced in such a system could become globally polarized along the direction of the system angular momentum. We present the results of Lambda and anti-Lambda hyperon global polarization measurements in Au+Au collisions at sqrt{s_NN}=62.4 GeV and 200 GeV performed with the STAR detector at RHIC. The observed global polarization of Lambda and anti-Lambda hyperons in the STAR acceptance is consistent with zero within the precision of the measurements. The obtained upper limit, |P_{Lambda,anti-Lambda}| <= 0.02, is compared to the theoretical values discussed recently in the literature.

11 data tables

(Color online) Invariant mass distribution for the $\Lambda$ (filled circles) and $\overline{\Lambda}$ (open squares) candidates after the quality cuts for Au+Au collisions at $\sqrt{s_{NN}}$=62.4 GeV (centrality region 0-80%).

(Color online) Global polarization of $\Lambda$–hyperons as a function of $\Lambda$ transverse momentum $p^{\Lambda}_{t}$. Filled circles show the results for Au+Au collisions at $\sqrt{s_{NN}}$=200 GeV (centrality region 20-70%) and open squares indicate the results for Au+Au collisions at $\sqrt{s_{NN}}$=62.4 GeV (centrality region 0-80%). Only statistical uncertainties are shown.

(Color online) Global polarization of $\Lambda$–hyperons as a function of $\Lambda$ pseudorapidity $\eta^{\Lambda}$. Filled circles show the results for Au+Au collisions at $\sqrt{s_{NN}}$=200 GeV (centrality region 20-70%). A constant line fit to these data points yields $P_{\Lambda}=(2.8\pm 9.6)\times 10^{-3}$ with $\chi^{2}/ndf=6.5/10$. Open squares show the results for Au+Au collisions at $\sqrt{s_{NN}}$=62.4 GeV (centrality region 0-80%). A constant line fit gives $P_{\Lambda}=(1.9\pm 8.0)\times 10^{-3}$ with $\chi^{2}/ndf=14.3/10$. Only statistical uncertainties are shown.

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Observation of an Energy-Dependent Difference in Elliptic Flow between Particles and Antiparticles 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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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 $r_5$.


Version 2
Measurement of the Bottom contribution to non-photonic electron production in $p+p$ collisions at $\sqrt{s} $=200 GeV

The STAR collaboration Aggarwal, M.M. ; Ahammed, Z. ; Alakhverdyants, A.V. ; et al.
Phys.Rev.Lett. 105 (2010) 202301, 2010.
Inspire Record 860571 DOI 10.17182/hepdata.101352

The contribution of $B$ meson decays to non-photonic electrons, which are mainly produced by the semi-leptonic decays of heavy flavor mesons, in $p+p$ collisions at $\sqrt{s} =$ 200 GeV has been measured using azimuthal correlations between non-photonic electrons and hadrons. The extracted $B$ decay contribution is approximately 50% at a transverse momentum of $p_{T} \geq 5$ GeV/$c$. These measurements constrain the nuclear modification factor for electrons from $B$ and $D$ meson decays. The result indicates that $B$ meson production in heavy ion collisions is also suppressed at high $p_{T}$.

3 data tables

Distributions of the azimuthal angle between nonphotonic electrons and charged hadrons normalized per nonphotonic electron trigger. The trigger electron has (top) $2.5 < p_{T} < 3.5$ GeV/$c$ and (bottom) $5.5 < p_{T} < 6.5$ GeV/$c$. The curves represent PYTHIA calculations for $D$ (dotted curve) and $B$ (dashed curve) decays. The fit result is shown as the black solid curve.

(a) Background-subtracted invariant mass distribution of $K$ pairs requiring at least one nonphotonic electron trigger in the event. The solid line is a Gaussian fit to the data near the peak region. (b) Distribution of the azimuthal angle between nonphotonic electron (positron) trigger particles and $D^{0}$ ($\bar{D}^{0}$). The solid (dashed) line is a fit of the correlation function from PYTHIA (MC$@$NLO) simulations to the data points.

Transverse momentum dependence of the relative contribution from $B$ mesons ($r_{B}$) to the nonphotonic electron yields. Error bars are statistical and brackets are systematic uncertainties. The solid curve is the FONLL calculation [14]. Theoretical uncertainties are indicated by the dashed curves.


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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Studying Parton Energy Loss in Heavy-Ion Collisions via Direct-Photon and Charged-Particle Azimuthal Correlations

The STAR collaboration Abelev, B.I. ; Aggarwal, M.M. ; Ahammed, Z. ; et al.
Phys.Rev.C 82 (2010) 034909, 2010.
Inspire Record 839470 DOI 10.17182/hepdata.101353

Charged-particle spectra associated with direct photon ($\gamma_{dir} $) and $\pi^0$ are measured in $p$+$p$ and Au+Au collisions at center-of-mass energy $\sqrt{s_{_{NN}}}=200$ GeV with the STAR detector at RHIC. A hower-shape analysis is used to partially discriminate between $\gamma_{dir}$ and $\pi^0$. Assuming no associated charged particles in the $\gamma_{dir}$ direction (near side) and small contribution from fragmentation photons ($\gamma_{frag}$), the associated charged-particle yields opposite to $\gamma_{dir}$ (away side) are extracted. At mid-rapidity ($|\eta|<0.9$) in central Au+Au collisions, charged-particle yields associated with $\gamma_{dir}$ and $\pi^0$ at high transverse momentum ($8< p_{T}^{trig}<16$ GeV/$c$) are suppressed by a factor of 3-5 compared with $p$ + $p$ collisions. The observed suppression of the associated charged particles, in the kinematic range $|\eta|<1$ and $3< p_{T}^{assoc} < 16$ GeV/$c$, is similar for $\gamma_{dir}$ and $\pi^0$, and independent of the $\gamma_{dir}$ energy within uncertainties. These measurements indicate that the parton energy loss, in the covered kinematic range, is insensitive to the parton path length.

4 data tables

The $z_{T}$ dependence of $\pi^{0}-h^{\pm}$ near side and away-side associated particle yields. The errors denoted 'syst' are systematic errors correlated in $z_{T}$. The errors denoted 'syst uncorr' are point-to-point systematic errors.

The $z_{T}$ dependence of away-side associated-particle yields for $\pi^{0}-h^{\pm}$ triggers and $\gamma_{dir}$ triggers. The errors denoted 'syst' are systematic errors correlated in $z_{T}$. The errors denoted 'syst uncorr' are point-to-point systematic errors.

The $z_{T}$ dependence $I_{AA}$ for $\pi^{0}-h^{\pm}$ triggers and $\gamma_{dir}$ triggers. The errors denoted 'syst' are systematic errors correlated in $z_{T}$. The errors denoted 'syst uncorr' are point-to-point systematic errors.

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Minijet deformation and charge-independent angular correlations on momentum subspace (eta, phi) in Au-Au collisions at s(NN)**(1/2) = 130-GeV

The STAR collaboration Adams, John ; Aggarwal, M.M. ; Ahammed, Z. ; et al.
Phys.Rev.C 73 (2006) 064907, 2006.
Inspire Record 663650 DOI 10.17182/hepdata.102089

First measurements of charge-independent correlations on angular difference variables $\eta_1 - \eta_2$ (pseudorapidity) and $\phi_1 - \phi_2$ (azimuth) are presented for primary charged hadrons with transverse momentum $0.15 \leq p_t \leq 2$ GeV/$c$ and $|\eta| \leq 1.3$ from Au-Au collisions at $\sqrt{s_{NN}} = 130$ GeV. Strong charge-independent angular correlations are observed associated with jet-like structures and elliptic flow. The width of the jet-like peak on $\eta_1 - \eta_2$ increases by a factor 2.3 from peripheral to central collisions, suggesting strong coupling of semi-hard scattered partons to a longitudinally-expanding medium. New methods of jet analysis introduced here provide evidence for nonperturbative QCD medium effects in heavy ion collisions.

4 data tables

Two-particle CI joint autocorrelations $\widehat{N}(\widehat{r}-1)$ on $(\eta_{\Delta}, \phi_{\Delta})$ for most-central collisions.

Two-particle CI joint autocorrelations $\widehat{N}(\widehat{r}-1)$ on $(\eta_{\Delta}, \phi_{\Delta})$ for mid-central collisions.

Two-particle CI joint autocorrelations $\widehat{N}(\widehat{r}-1)$ on $(\eta_{\Delta}, \phi_{\Delta})$ for mid-peripheral collisions.

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Hadronization geometry and charge-dependent number autocorrelations on axial momentum space in Au-Au collisions at s(NN)**(1/2) = 130-GeV

The STAR collaboration Adams, John ; Aggarwal, M.M. ; Ahammed, Z. ; et al.
Phys.Lett.B 634 (2006) 347-355, 2006.
Inspire Record 653486 DOI 10.17182/hepdata.102088

We present the first measurements of charge-dependent correlations on angular difference variables $\eta_1 - \eta_2$ (pseudorapidity) and $\phi_1 - \phi_2$ (azimuth) for primary charged hadrons with transverse momentum $0.15 \leq p_t \leq 2$ GeV/$c$ and $|\eta| \leq 1.3$ from Au-Au collisions at $\sqrt{s_{NN}} = 130$ GeV. We observe correlation structures not predicted by theory but consistent with evolution of hadron emission geometry with increasing centrality from one-dimensional fragmentation of color strings along the beam direction to an at least two-dimensional hadronization geometry along the beam and azimuth directions of a hadron-opaque bulk medium.

6 data tables

Normalized LS pair-number ratios $\widehat{r} [X(p_{t1}),X(p_{t2})]-1$ for collisions in centrality class (a) (most-central) in $(\eta_{1},\eta_{2})$.

Normalized LS pair-number ratios $\widehat{r} [X(p_{t1}),X(p_{t2})]-1$ for collisions in centrality class (a) (most-central) in $(\phi_{1},\phi_{2})$.

Two-particle CD joint autocorrelations $\widehat{N}(\widehat{r}-1)$ on $(\eta_{\Delta}, \phi_{\Delta})$ for most-central collisions.

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Measurement of transverse single-spin asymmetries for di-jet production in proton-proton collisions at s**(1/2) = 200-GeV

The STAR collaboration Abelev, B.I. ; Aggarwal, M.M. ; Ahammed, Z. ; et al.
Phys.Rev.Lett. 99 (2007) 142003, 2007.
Inspire Record 751885 DOI 10.17182/hepdata.102938

We report the first measurement of the opening angle distribution between pairs of jets produced in high-energy collisions of transversely polarized protons. The measurement probes (Sivers) correlations between the transverse spin orientation of a proton and the transverse momentum directions of its partons. With both beams polarized, the wide pseudorapidity ($-1 \leq \eta \leq +2$) coverage for jets permits separation of Sivers functions for the valence and sea regions. The resulting asymmetries are all consistent with zero and considerably smaller than Sivers effects observed in semi-inclusive deep inelastic scattering (SIDIS). We discuss theoretical attempts to reconcile the new results with the sizable transverse spin effects seen in SIDIS and forward hadron production in pp collisions.

4 data tables

Measured and calculated asymmetries vs. di-jet pseudorapidity sum for $+\hat{z}$ (left) and $−\hat{z}$ (right) beams. (a,b): Fraction of the calculated di-jet cross section with a quark (gluon) from the $+\hat{z}$ $(−\hat{z})$ beam. (c,d): Unweighted asymmetries compared with pQCD calculations [20] (histograms) for two models of quark Sivers functions fitted to SIDIS results [8]. (e,f): Asymmetries for $|\sin\zeta|$-weighted yields, compared with calculations [20, 21] based on twist-3 quark-gluon correlations. Vertical (horizontal) bars on the data indicate statistical uncertainties (bin widths). The systematic error bands exclude a $\pm12\%$ beam polarization normalization uncertainty.

Measured and calculated asymmetries vs. di-jet pseudorapidity sum for $+\hat{z}$ (left) and $−\hat{z}$ (right) beams. (a,b): Fraction of the calculated di-jet cross section with a quark (gluon) from the $+\hat{z}$ $(−\hat{z})$ beam. (c,d): Unweighted asymmetries compared with pQCD calculations [20] (histograms) for two models of quark Sivers functions fitted to SIDIS results [8]. (e,f): Asymmetries for $|\sin\zeta|$-weighted yields, compared with calculations [20, 21] based on twist-3 quark-gluon correlations. Vertical (horizontal) bars on the data indicate statistical uncertainties (bin widths). The systematic error bands exclude a $\pm12\%$ beam polarization normalization uncertainty.

Measured and calculated asymmetries vs. di-jet pseudorapidity sum for $+\hat{z}$ (left) and $−\hat{z}$ (right) beams. (a,b): Fraction of the calculated di-jet cross section with a quark (gluon) from the $+\hat{z}$ $(−\hat{z})$ beam. (c,d): Unweighted asymmetries compared with pQCD calculations [20] (histograms) for two models of quark Sivers functions fitted to SIDIS results [8]. (e,f): Asymmetries for $|\sin\zeta|$-weighted yields, compared with calculations [20, 21] based on twist-3 quark-gluon correlations. Vertical (horizontal) bars on the data indicate statistical uncertainties (bin widths). The systematic error bands exclude a $\pm12\%$ beam polarization normalization uncertainty.

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Strange baryon resonance production in s(NN)**(1/2) = 200-GeV p+p and Au+Au collisions

The STAR collaboration Abelev, B.I. ; Aggarwal, M.M. ; Ahammed, Z. ; et al.
Phys.Rev.Lett. 97 (2006) 132301, 2006.
Inspire Record 715471 DOI 10.17182/hepdata.102937

We report the measurements of $\Sigma (1385)$ and $\Lambda (1520)$ production in $p+p$ and $Au+Au$ collisions at $\sqrt{s_{NN}} = 200$ GeV from the STAR collaboration. The yields and the $p_{T}$ spectra are presented and discussed in terms of chemical and thermal freeze-out conditions and compared to model predictions. Thermal and microscopic models do not adequately describe the yields of all the resonances produced in central $Au+Au$ collisions. Our results indicate that there may be a time-span between chemical and thermal freeze-out during which elastic hadronic interactions occur.

2 data tables

The transverse mass spectra for $\Sigma^{∗}$ and $\Lambda^{∗}$ in p+p and in central Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV. Statistical and systematical errors are included.

Resonance to stable particle ratios for p + p and Au + Au collisions. The ratios are normalized to unity in p + p and compared to thermal and UrQMD model predictions for central Au + Au [8, 12]. Statistical and systematic uncertainties are included in the error bars. (In the paper figure, K*/K dNCh/dy axis is shifted +30 for visual purposes to seperate the error bar contributions.)


Transverse-momentum p(t) correlations on (eta, phi) from mean-p(t) fluctuations in Au-Au collisions at s(NN)**1/2 = 200-GeV

The STAR collaboration Adams, John ; Aggarwal, M.M. ; Ahammed, Z. ; et al.
J.Phys.G 32 (2006) L37-L48, 2006.
Inspire Record 693136 DOI 10.17182/hepdata.102092

We present first measurements of the pseudorapidity and azimuth $(\eta,\phi)$ bin-size dependence of event-wise mean transverse momentum $<p_{t} >$ fluctuations for Au-Au collisions at $\sqrt{s_{NN}} = 200$ GeV. We invert that dependence to obtain $p_t$ autocorrelations on differences $(\eta_\Delta,\phi_\Delta)$ interpreted to represent velocity/temperature distributions on ($\eta,\phi$). The general form of the autocorrelations suggests that the basic correlation mechanism is parton fragmentation. The autocorrelations vary strongly with collision centrality, which suggests that fragmentation is strongly modified by a dissipative medium in the more central

1 data table

Correlation amplitudes $B_{1}, B_{2}, B_{3}$ as well as positive-peak widths for pseudorapidity ($\sigma_{\eta_{1}}$) and azimuth ($\sigma_{\phi_{1}}$), plotted on mean participant path length $\nu$.


Transverse-momentum dependent modification of dynamic texture in central Au+Au collisions at s(NN)**(1/2) = 200-GeV

The STAR collaboration Adams, J. ; Aggarwal, M.M. ; Ahammed, Z. ; et al.
Phys.Rev.C 71 (2005) 031901, 2005.
Inspire Record 653628 DOI 10.17182/hepdata.102943

Correlations in the hadron distributions produced in relativistic Au+Au collisions are studied in the discrete wavelet expansion method. The analysis is performed in the space of pseudorapidity (|eta| < 1) and azimuth (full 2 pi) in bins of transverse momentum (p_t) from 0.14 < p_t < 2.1 GeV/c. In peripheral Au+Au collisions a correlation structure ascribed to mini-jet fragmentation is observed. It evolves with collision centrality and p_t in a way not seen before which suggests strong dissipation of minijet fragmentation in the longitudinally-expanding medium.

10 data tables

Normalized dynamic texture for fineness scale m = 0

Normalized dynamic texture for fineness scale m = 1

Normalized dynamic texture for fineness scale m = 0

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Incident energy dependence of pt correlations at RHIC

The STAR collaboration Adams, J. ; Aggarwal, M.M. ; Ahammed, Z. ; et al.
Phys.Rev.C 72 (2005) 044902, 2005.
Inspire Record 681688 DOI 10.17182/hepdata.102946

We present results for two-particle transverse momentum correlations, <dpt,i dpt,j>, as a function of event centrality for Au+Au collisions at sqrt(sNN) = 20, 62, 130, and 200 GeV at the Relativistic Heavy Ion Collider. We observe correlations decreasing with centrality that are similar at all four incident energies. The correlations multiplied by the multiplicity density increase with incident energy and the centrality dependence may show evidence of processes such as thermalization, minijet production, or the saturation of transverse flow. The square root of the correlations divided by the event-wise average transverse momentum per event shows little or no beam energy dependence and generally agrees with previous measurements at the Super Proton Synchrotron.

8 data tables

Average transverse momentum per event for Au+Au at $\sqrt{s_{NN}}$ = 20 GeV for the 5% most central collisions.

Average transverse momentum per event for Au+Au at $\sqrt{s_{NN}}$ = 62 GeV for the 5% most central collisions.

Average transverse momentum per event for Au+Au at $\sqrt{s_{NN}}$ = 130 GeV for the 5% most central collisions.

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Beam-Energy Dependence of Directed Flow of $\Lambda$, $\bar{\Lambda}$, $K^\pm$, $K^0_s$ and $\phi$ in Au+Au Collisions

The STAR collaboration Adamczyk, Leszek ; Adams, Joseph ; Adkins, Kevin ; et al.
Phys.Rev.Lett. 120 (2018) 062301, 2018.
Inspire Record 1618747 DOI 10.17182/hepdata.101750

Rapidity-odd directed flow measurements at midrapidity are presented for $\Lambda$, $\bar{\Lambda}$, $K^\pm$, $K^0_s$ and $\phi$ at $\sqrt{s_{NN}} =$ 7.7, 11.5, 14.5, 19.6, 27, 39, 62.4 and 200 GeV in Au+Au collisions recorded by the STAR detector at the Relativistic Heavy Ion Collider. These measurements greatly expand the scope of data available to constrain models with differing prescriptions for the equation of state of quantum chromodynamics. Results show good sensitivity for testing a picture where flow is assumed to be imposed before hadron formation and the observed particles are assumed to form via coalescence of constituent quarks. The pattern of departure from a coalescence-inspired sum-rule can be a valuable new tool for probing the collision dynamics.

49 data tables

Directed flow $v_1$ as a function of rapidity $y$ for $p$ in 5%–10% central Au+Au collisions at $\sqrt{s_{NN}} =$ 7.7, 11.5, 14.5, 19.6, 27, 39, 62.4 and 200 GeV.

Directed flow $v_1$ as a function of rapidity $y$ for $p$ in 10%–40% central Au+Au collisions at $\sqrt{s_{NN}} =$ 7.7, 11.5, 14.5, 19.6, 27, and 39 GeV.

Directed flow $v_1$ as a function of rapidity $y$ for $p$ in 10%–40% central Au+Au collisions at $\sqrt{s_{NN}} =$ 62.4 and 200 GeV.

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Dijet imbalance measurements in $Au+Au$ and $pp$ collisions at $\sqrt{s_{NN}} = 200$ GeV at STAR

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.Lett. 119 (2017) 062301, 2017.
Inspire Record 1486427 DOI 10.17182/hepdata.102941

We report the first di-jet transverse momentum asymmetry measurements from Au+Au and p+p collisions at RHIC. The two highest-energy back-to-back jets reconstructed from fragments with transverse momenta above 2 GeV/c display a significantly stronger momentum imbalance in heavy-ion collisions than in the p+p reference. When re-examined with correlated soft particles included, we observe that these di-jets then exhibit a unique new feature -- momentum balance is restored to that observed in p+p for a jet resolution parameter of R=0.4, while re-balancing is not attained with a smaller value of R=0.2.

11 data tables

Normalized AJ distributions for Au+Au HT data (filled symbols) and p+p HT $\oplus$ Au+Au MB (open symbols). The red circles points are for jets found using only constituents with $p^{Cut}_{T} > 2$ GeV/$c$ and the black squares for matched jets found using constituents with $p^{Cut}_{T} > 0.2$ GeV/$c$. In all cases $R = 0.4$.