Beam-energy dependence of identified two-particle angular correlations in $\sqrt {s_{NN}}$ = 7.7–200 GeV Au+Au collisions

The STAR collaboration Adam, Jaroslav ; Adams, Joseph ; Agakishiev, Geydar ; et al.
Phys.Rev.C 101 (2020) 014916, 2020.
Inspire Record 1740846 DOI 10.17182/hepdata.105909

The two-particle angular correlation functions, $R_2$, of pions, kaons, and protons in Au+Au collisions at $\sqrt{s_{NN}}=$ 7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV were measured by the STAR experiment at RHIC. These correlations were measured for both like-sign and unlike-sign charge combinations and versus the centrality. The correlations of pions and kaons show the expected near-side ({\it i.e.}, at small relative angles) peak resulting from short-range mechanisms. The amplitudes of these short-range correlations decrease with increasing beam energy. However, the proton correlation functions exhibit strong anticorrelations in the near-side region. This behavior is observed for the first time in an A+A collision system. The observed anticorrelation is $p_{T}$-independent and decreases with increasing beam energy and centrality. The experimental results are also compared to the Monte Carlo models UrQMD, Hijing, and AMPT.

44 data tables

Angular correlation function R2(∆y,∆φ) of like-sign pions in Au+Au collisions at mid centrality 30%-40% and 0.2 < pT < 2.0 GeV/c at 7.7 GeV

Angular correlation function R2(∆y,∆φ) of like-sign pions in Au+Au collisions at mid centrality 30%-40% and 0.2 < pT < 2.0 GeV/c at 11.5 GeV

Angular correlation function R2(∆y,∆φ) of like-sign pions in Au+Au collisions at mid centrality 30%-40% and 0.2 < pT < 2.0 GeV/c at 14.5 GeV

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Beam energy dependence of net- Λ fluctuations measured by the STAR experiment at the BNL Relativistic Heavy Ion Collider

The STAR collaboration Adam, Jaroslav ; Adamczyk, Leszek ; Adams, Joseph ; et al.
Phys.Rev.C 102 (2020) 024903, 2020.
Inspire Record 1776194 DOI 10.17182/hepdata.113523

The measurements of particle multiplicity distributions have generated considerable interest in understanding the fluctuations of conserved quantum numbers in the Quantum Chromodynamics (QCD) hadronization regime, in particular near a possible critical point and near the chemical freeze-out. We report the measurement of efficiency and centrality bin width corrected cumulant ratios ($C_{2}/C_{1}$, $C_{3}/C_{2}$) of net-$\Lambda$ distributions, in the context of both strangeness and baryon number conservation, as a function of collision energy, centrality and rapidity. The results are for Au + Au collisions at five beam energies ($\sqrt{s_{NN}}$ = 19.6, 27, 39, 62.4 and 200 GeV) recorded with the Solenoidal Tracker at RHIC (STAR). We compare our results to the Poisson and negative binomial (NBD) expectations, as well as to Ultra-relativistic Quantum Molecular Dynamics (UrQMD) and Hadron Resonance Gas (HRG) model predictions. Both NBD and Poisson baselines agree with data within the statistical and systematic uncertainties. The ratios of the measured cumulants show no features of critical fluctuations. The chemical freeze-out temperatures extracted from a recent HRG calculation, which was successfully used to describe the net-proton, net-kaon and net-charge data, indicate $\Lambda$ freeze-out conditions similar to those of kaons. However, large deviations are found when comparing to temperatures obtained from net-proton fluctuations. The net-$\Lambda$ cumulants show a weak, but finite, dependence on the rapidity coverage in the acceptance of the detector, which can be attributed to quantum number conservation.

35 data tables

Centrality dependence of single cumulants C1, of net-lambda multiplicity distributions at Au + Au collision 19.6 GeV. Values are shown with NBD, Poisson and UrQMD predictions. Npart values are from Phys. Rev. C 104, 024902 (2021) and they are little different than the values shown in the original paper.

Centrality dependence of single cumulants C1, of net-lambda multiplicity distributions at Au + Au collision 27 GeV. Values are shown with NBD, Poisson and UrQMD predictions.Npart values are from Phys. Rev. C 104, 024902 (2021) and they are little different than the values shown in the original paper.

Centrality dependence of single cumulants C1, of net-lambda multiplicity distributions at Au + Au collision 39 GeV. Values are shown with NBD, Poisson and UrQMD predictions.Npart values are from Phys. Rev. C 104, 024902 (2021) and they are little different than the values shown in the original paper.

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Nonmonotonic Energy Dependence of Net-Proton Number Fluctuations

The STAR collaboration Adam, J. ; Adam, J. ; Adamczyk, L. ; et al.
Phys.Rev.Lett. 126 (2021) 092301, 2021.
Inspire Record 1774673 DOI 10.17182/hepdata.101068

Observations from collisions of heavy-ion at relativistic energies have established the formation of a new phase of matter, Quark Gluon Plasma (QGP), a deconfined state of quarks and gluons in a specific region of the temperature versus baryonic chemical potential phase diagram of strong interactions. A program to study the features of the phase diagram, such as a possible critical point, by varying the collision energy ($\sqrt{s_{\rm NN}}$), is performed at the Relativistic Heavy-Ion Collider (RHIC) facility. Non-monotonic variation with $\sqrt{s_{\rm NN}}$ of moments of the net-baryon number distribution, related to the correlation length and the susceptibilities of the system, is suggested as a signature for a critical point. We report the first evidence of a non-monotonic variation in kurtosis $\times$ variance of the net-proton number (proxy for net-baryon number) distribution as a function of $\sqrt{s_{\rm NN}}$ with 3.1$\sigma$ significance, for head-on (central) gold-on-gold (Au+Au) collisions measured using the STAR detector at RHIC. Non-central Au+Au collisions and models of heavy-ion collisions without a critical point show a monotonic variation as a function of $\sqrt{s_{\rm NN}}$.

10 data tables

Event-by-event net-proton multiplicity distributions for central (0-5$\%$) Au+Au collisions from $\sqrt{s_{NN}} = 7.7 - 200 GeV. The distributions are normalised to total number of events. The distributions are not corrected for proton and antiproton detection efficiency.

Cumulants of net-proton distributions in Au+Au collisions for nine energies from $\sqrt{s_{NN}} = 7.7 - 200 GeV for 0-5$\%$ and 70-80$\%$ centrality.

Cumulant ratios C3/C2 and C4/C2 of net-proton distributions in Au+Au collisions for eight energies from $\sqrt{s_{NN}} = 7.7 - 62.4 GeV for 0-5$\%$ centrality. Also given are the derivative of the polynomial fits to the C3/C2 and C4/C2 vs energy at each energy and the Skellam baselines for the ratios.

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Cumulants and correlation functions of net-proton, proton, and antiproton multiplicity distributions in Au+Au collisions at energies available at the BNL Relativistic Heavy Ion Collider

The STAR collaboration Abdallah, Mohamed ; Adam, Jaroslav ; Adamczyk, Leszek ; et al.
Phys.Rev.C 104 (2021) 024902, 2021.
Inspire Record 1843941 DOI 10.17182/hepdata.101356

We report a systematic measurement of cumulants, $C_{n}$, for net-proton, proton and antiproton multiplicity distributions, and correlation functions, $\kappa_n$, for proton and antiproton multiplicity distributions up to the fourth order in Au+Au collisions at $\sqrt{s_{\mathrm {NN}}}$ = 7.7, 11.5, 14.5, 19.6, 27, 39, 54.4, 62.4 and 200 GeV. The $C_{n}$ and $\kappa_n$ are presented as a function of collision energy, centrality and kinematic acceptance in rapidity, $y$, and transverse momentum, $p_{T}$. The data were taken during the first phase of the Beam Energy Scan (BES) program (2010 -- 2017) at the BNL Relativistic Heavy Ion Collider (RHIC) facility. The measurements are carried out at midrapidity ($|y| <$ 0.5) and transverse momentum 0.4 $<$$p_{\rm T}$$<$ 2.0 GeV/$c$, using the STAR detector at RHIC. We observe a non-monotonic energy dependence ($\sqrt{s_{\mathrm {NN}}}$ = 7.7 -- 62.4 GeV) of the net-proton $C_{4}$/$C_{2}$ with the significance of 3.1$\sigma$ for the 0-5% central Au+Au collisions. This is consistent with the expectations of critical fluctuations in a QCD-inspired model. Thermal and transport model calculations show a monotonic variation with $\sqrt{s_{\mathrm {NN}}}$. For the multiparticle correlation functions, we observe significant negative values for a two-particle correlation function, $\kappa_2$, of protons and antiprotons, which are mainly due to the effects of baryon number conservation. Furthermore, it is found that the four-particle correlation function, $\kappa_4$, of protons plays a role in determining the energy dependence of proton $C_4/C_1$ below 19.6 GeV, which cannot be understood by the effect of baryon number conservation.

114 data tables

Reference charged particle multiplicity distributions using only pions and kaons ...

Reference charged particle multiplicity distributions using only pions and kaons ...

Reference charged particle multiplicity distributions using only pions and kaons ...

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Invariant Jet Mass Measurements in $pp$ Collisions at $\sqrt{s} = 200$ GeV at RHIC

The STAR collaboration Abdallah, Mohamed ; Adam, Jaroslav ; Adamczyk, Leszek ; et al.
Phys.Rev.D 104 (2021) 052007, 2021.
Inspire Record 1853218 DOI 10.17182/hepdata.102953

We present the first inclusive measurements of the invariant and SoftDrop jet mass in proton-proton collisions at $\sqrt{s}=200$ GeV at STAR. The measurements are fully corrected for detector effects, and reported differentially in both the jet transverse momentum and jet radius parameter. We compare the measurements to established leading-order Monte Carlo event generators and find that STAR-tuned PYTHIA-6 reproduces the data, while LHC tunes of PYTHIA-8 and HERWIG-7 do not agree with the data, providing further constraints on parameter tuning. Finally, we observe that SoftDrop grooming, for which the contribution of wide-angle non-perturbative radiation is suppressed, shifts the jet mass distributions into closer agreement with the partonic jet mass as determined by both PYTHIA-8 and a next-to-leading-logarithmic accuracy perturbative QCD calculation. These measurements complement recent LHC measurements in a different kinematic region, as well as establish a baseline for future jet mass measurements in heavy-ion collisions at RHIC.

22 data tables

The uncorrected jet mass distribution for $R = 0.4$ anti-$k_{\rm{T}}$ jets with $20 < p_{\rm{T,jet}} < 25$ GeV$/c$.

The uncorrected SoftDrop groomed jet mass distribution for $R = 0.4$ anti-$k_{\rm{T}}$ jets with $20 < p_{\rm{T,jet}} < 25$ GeV$/c$.

The fully corrected jet mass distribution for $R = 0.4$ anti-$k_{\rm{T}}$ jets with $20 < p_{\rm{T,jet}} < 25$ GeV$/c$. Data are reported beyond the x-axis upper limit of the figure, for future reference.

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Version 2
Evolution of the differential transverse momentum correlation function with centrality in Au$+$Au collisions at $\sqrt{s_{NN}} =$ 200 GeV

The STAR collaboration Agakishiev, H. ; Aggarwal, M.M. ; Ahammed, Z. ; et al.
Phys.Lett.B 704 (2011) 467-473, 2011.
Inspire Record 914546 DOI 10.17182/hepdata.102406

We present first measurements of the evolution of the differential transverse momentum correlation function, {\it C}, with collision centrality in Au+Au interactions at $\sqrt{s_{NN}} = 200$ GeV. {\it C} exhibits a strong dependence on collision centrality that is qualitatively similar to that of number correlations previously reported. We use the observed longitudinal broadening of the near-side peak of {\it C} with increasing centrality to estimate the ratio of the shear viscosity to entropy density, $\eta/s$, of the matter formed in central Au+Au interactions. We obtain an upper limit estimate of $\eta/s$ that suggests that the produced medium has a small viscosity per unit entropy.

7 data tables

The correlation function C, C is plotted in units of (GeV/c)$^2$ and the relative azimuthal angle ∆φ in radians for 70-80% centrality in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. Relative statistical errors range from 0.8% in peripheral collisions to 0.9% in the most central collisions at the peak of the distribution.

The correlation function C, C is plotted in units of (GeV/c)$^2$ and the relative azimuthal angle ∆φ in radians for 30-40% centrality in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. Relative statistical errors range from 0.8% in peripheral collisions to 0.9% in the most central collisions at the peak of the distribution.

The correlation function C, C is plotted in units of (GeV/c)$^2$ and the relative azimuthal angle ∆φ in radians for 0-5% centrality in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV..Relative statistical errors range from 0.8% in peripheral collisions to 0.9% in the most central collisions at the peak of the distribution.

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Observation of $D_{s}^{\pm}/D^0$ enhancement in Au+Au collisions at $\sqrt{s_{_{NN}}}$ = 200 GeV

The STAR collaboration Adam, J. ; Adamczyk, L. ; Adams, J.R. ; et al.
Phys.Rev.Lett. 127 (2021) 092301, 2021.
Inspire Record 1843268 DOI 10.17182/hepdata.101172

We report on the first measurement of charm-strange meson $D_s^{\pm}$ production at midrapidity in Au+Au collisions at $\sqrt{s_{_{\rm NN}}}$ = 200 GeV from the STAR experiment. The yield ratio between strange ($D_{s}^{\pm}$) and non-strange ($D^{0}$) open-charm mesons is presented and compared to model calculations. A significant enhancement, relative to a PYTHIA simulation of $p$+$p$ collisions, is observed in the $D_{s}^{\pm}/D^0$ yield ratio in Au+Au collisions over a large range of collision centralities. Model calculations incorporating abundant strange-quark production in the quark-gluon plasma (QGP) and coalescence hadronization qualitatively reproduce the data. The transverse-momentum integrated yield ratio of $D_{s}^{\pm}/D^0$ at midrapidity is consistent with a prediction from a statistical hadronization model with the parameters constrained by the yields of light and strange hadrons measured at the same collision energy. These results suggest that the coalescence of charm quarks with strange quarks in the QGP plays an important role in $D_{s}^{\pm}$ meson production in heavy-ion collisions.

10 data tables

The $KK\pi$ invariant mass distribution (Counts per 8 MeV/$c^{2}$ bin) for right-sign combinations in 0-80% Au+Au collisions at $\sqrt{s_{_{\rm NN}}}$ = 200 GeV.

$D_s^{\pm}$ invariant yield as a function of $p_{T}$ in 0-10% centrality bin of Au+Au collisions at $\sqrt{s_{_{\rm NN}}}$ = 200 GeV. The $p_T$ bins are 1.5 < $p_T$ < 2.5 GeV/c, 2.5 < $p_T$ < 3.5 GeV/c, 3.5 < $p_T$ < 5.0 GeV/c and 5.0 < $p_T$ < 8.0 GeV/c.

$D_s^{\pm}$ invariant yield as a function of $p_{T}$ in 10-40% centrality bin of Au+Au collisions at $\sqrt{s_{_{\rm NN}}}$ = 200 GeV. The $p_T$ bins are 1.0 < $p_T$ < 2.0 GeV/c, 2.0 < $p_T$ < 2.5 GeV/c, 2.5 < $p_T$ < 3.5 GeV/c, 3.5 < $p_T$ < 5.0 GeV/c and 5.0 < $p_T$ < 8.0 GeV/c.

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Version 2
Centrality and transverse momentum dependence of $D^0$-meson production at mid-rapidity in Au+Au collisions at ${\sqrt{s_{\rm NN}} = \rm{200\,GeV}}$

The STAR collaboration Adam, Jaroslav ; Adamczyk, Leszek ; Adams, Joseph ; et al.
Phys.Rev.C 99 (2019) 034908, 2019.
Inspire Record 1711377 DOI 10.17182/hepdata.95750

We report a new measurement of $D^0$-meson production at mid-rapidity ($|y|$\,$<$\,1) in Au+Au collisions at ${\sqrt{s_{\rm NN}} = \rm{200\,GeV}}$ utilizing the Heavy Flavor Tracker, a high resolution silicon detector at the STAR experiment. Invariant yields of $D^0$-mesons with transverse momentum $p_{T}$ $\lesssim 9$\,GeV/$c$ are reported in various centrality bins (0--10\%, 10--20\%, 20--40\%, 40--60\% and 60--80\%). Blast-Wave thermal models are used to fit the $D^0$-meson $p_{T}$ spectra to study $D^0$ hadron kinetic freeze-out properties. The average radial flow velocity extracted from the fit is considerably smaller than that of light hadrons ($\pi,K$ and $p$), but comparable to that of hadrons containing multiple strange quarks ($\phi,\Xi^-$), indicating that $D^0$ mesons kinetically decouple from the system earlier than light hadrons. The calculated $D^0$ nuclear modification factors re-affirm that charm quarks suffer large amount of energy loss in the medium, similar to those of light quarks for $p_{T}$\,$>$\,4\,GeV/$c$ in central 0--10\% Au+Au collisions. At low $p_{T}$, the nuclear modification factors show a characteristic structure qualitatively consistent with the expectation from model predictions that charm quarks gain sizable collective motion during the medium evolution. The improved measurements are expected to offer new constraints to model calculations and help gain further insights into the hot and dense medium created in these collisions.

22 data tables

$D^0$ invariant yield at mid-rapidity ($|y| < 1$) vs transverse momentum for different centrality classes. Error bars indicate statistical uncertainties and brackets depict systematic uncertainties. Global systematic uncertainties in B.R. are not plotted. Solid and dashed lines depict Levy function fits.

$D^0$ spectra in pp collisions

Integrated $D^0$ cross section per nucleon-nucleon collision at mid-rapidity for $p_T >0$ (a) and $p_T >4$ GeV/c (b) as a function of centrality $N_{part}$. The statistical and systematic uncertainties are shown as error bars and brackets on the data points. The green boxes on the data points depict the overall normalization uncertainties in p+p and Au+Au data respectively.

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Erratum: Azimuthal Anisotropy of KS0 and Λ+Λ¯ Production at Midrapidity from Au+Au Collisions at sNN=130  GeV [Phys. Rev. Lett. 89, 132301 (2002)]

The STAR collaboration Adler, C. ; Ahammed, Z. ; Allgower, C. ; et al.
Phys.Rev.Lett. 127 (2021) 089901, 2021.
Inspire Record 587154 DOI 10.17182/hepdata.102318

We report STAR results on the azimuthal anisotropy parameter v2 for strange particles K0S, L and Lbar at midrapidity in Au+Au collisions at sNN = 130 GeV at RHIC. The value of v2 as a function of transverse momentum of the produced particles pt and collision centrality is presented for both particles up to pt 3.0 GeV/c. A strong pt dependence in v2 is observed up to 2.0 GeV/c. The v2 measurement is compared with hydrodynamic model calculations. The physics implications of the pt integrated v2 magnitude as a function of particle mass are also discussed.

8 data tables

$v_2$ of $K_s^0$ as a function of $p_T$ for 0-11% centrality in Au+Au collisions at 130 GeV. Systematic errors of $\pm$0.005 for particle identification and background subtraction and $^{+0}_{-0.005}$ for nonflow effects.

$v_2$ of $K_s^0$ as a function of $p_T$ for 11-45% centrality in Au+Au collisions at 130 GeV. Systematic errors of $\pm$0.005 for particle identification and background subtraction and $^{+0}_{-0.005}$ for nonflow effects.

$v_2$ of $\Lambda+\bar{\Lambda}$ as a function of $p_T$ for 0-11% centrality in Au+Au collisions at 130 GeV. Systematic errors of $\pm$0.005 for particle identification and background subtraction and $^{+0}_{-0.005}$ for nonflow effects.

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Erratum: Azimuthal Anisotropy at the Relativistic Heavy Ion Collider: The First and Fourth Harmonics [Phys. Rev. Lett. 92, 062301 (2004)]

The STAR collaboration Adams, J. ; Adler, C. ; Aggarwal, M.M. ; et al.
Phys.Rev.Lett. 127 (2021) 069901, 2021.
Inspire Record 631713 DOI 10.17182/hepdata.102322

We report the first observations of the first harmonic (directed flow, v_1), and the fourth harmonic (v_4), in the azimuthal distribution of particles with respect to the reaction plane in Au+Au collisions at the Relativistic Heavy Ion Collider (RHIC). Both measurements were done taking advantage of the large elliptic flow (v_2) generated at RHIC. From the correlation of v_2 with v_1 it is determined that v_2 is positive, or {\it in-plane}. The integrated v_4 is about a factor of 10 smaller than v_2. For the sixth (v_6) and eighth (v_8) harmonics upper limits on the magnitudes are reported.

6 data tables

$v_1$ of charged particles as a function of pseudorapidity for 10-70% centrality. Non-flow systematic uncertainties are approximately 20%.

$v_2$ with respect to the second harmonic event plane as a function of $p_T$ for the minimum bias Au+Au collisions. Background from secondary particles is expected to be less than 15%. Non-flow systematic uncertainties are approximately 20%. Fluctuations in initial geometry can lead to an effect of about a factor of 1.2 to 1.5.

$v_4$ with respect to the second harmonic event plane as a function of $p_T$ for the minimum bias Au+Au collisions. Background from secondary particles is expected to be less than 15%. Non-flow systematic uncertainties are approximately 20%. Fluctuations in initial geometry can lead to an effect of about a factor of 1.2 to 1.5.

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