Showing 10 of 300 results
We report the measurement of cumulants ($C_n, n=1\ldots4$) of the net-charge distributions measured within pseudorapidity ($|\eta|<0.35$) in Au$+$Au collisions at $\sqrt{s_{_{NN}}}=7.7-200$ GeV with the PHENIX experiment at the Relativistic Heavy Ion Collider. The ratios of cumulants (e.g. $C_1/C_2$, $C_3/C_1$) of the net-charge distributions, which can be related to volume independent susceptibility ratios, are studied as a function of centrality and energy. These quantities are important to understand the quantum-chromodynamics phase diagram and possible existence of a critical end point. The measured values are very well described by expectation from negative binomial distributions. We do not observe any nonmonotonic behavior in the ratios of the cumulants as a function of collision energy. The measured values of $C_1/C_2 = \mu/\sigma^2$ and $C_3/C_1 = S\sigma^3/\mu$ can be directly compared to lattice quantum-chromodynamics calculations and thus allow extraction of both the chemical freeze-out temperature and the baryon chemical potential at each center-of-mass energy.
We present measurements of the J/psi invariant yields in sqrt(s_NN)=39 and 62.4 GeV Au+Au collisions at forward rapidity (1.2<|y|<2.2). Invariant yields are presented as a function of both collision centrality and transverse momentum. Nuclear modifications are obtained for central relative to peripheral Au+Au collisions (R_CP) and for various centrality selections in Au+Au relative to scaled p+p cross sections obtained from other measurements (R_AA). The observed suppression patterns at 39 and 62.4 GeV are quite similar to those previously measured at 200 GeV. This similar suppression presents a challenge to theoretical models that contain various competing mechanisms with different energy dependencies, some of which cause suppression and others enhancement.
Notwithstanding decades of progress since Yukawa first developed a description of the force between nucleons in terms of meson exchange, a full understanding of the strong interaction remains a major challenge in modern science. One remaining difficulty arises from the non-perturbative nature of the strong force, which leads to the phenomenon of quark confinement at distances on the order of the size of the proton. Here we show that in relativistic heavy-ion collisions, where quarks and gluons are set free over an extended volume, two species of produced vector (spin-1) mesons, namely $\phi$ and $K^{*0}$, emerge with a surprising pattern of global spin alignment. In particular, the global spin alignment for $\phi$ is unexpectedly large, while that for $K^{*0}$ is consistent with zero. The observed spin-alignment pattern and magnitude for the $\phi$ cannot be explained by conventional mechanisms, while a model with a connection to strong force fields, i.e. an effective proxy description within the Standard Model and Quantum Chromodynamics, accommodates the current data. This connection, if fully established, will open a potential new avenue for studying the behaviour of strong force fields.
Global spin alignment of $\phi$ and $K^{*0}$ vector mesons in heavy-ion collisions. The measured matrix element $\rho_{00}$ as a function of beam energy for the $\phi$ and $K^{*0}$ vector mesons within the indicated windows of centrality, transverse momentum ($p_T$) and rapidity ($y$). The open symbols indicate ALICE results for Pb+Pb collisions at 2.76 TeV at $p_{T}$ values of 2.0 and 1.4 GeV/c for the $\phi$ and $K^{*0}$ mesons, respectively, corresponding to the $p_{T}$ bin nearest to the mean $p_{T}$ for the 1.0 – 5.0 GeV/$c$ range assumed for each meson in the present analysis. The red solid curve is a fit to data in the range of $\sqrt{s_{NN}} = 19.6$ to 200 GeV, based on a theoretical calculation with a $\phi$-meson field. Parameter sensitivity of $\rho_{00}$ to the $\phi$-meson field is shown in Ref.5. The red dashed line is an extension of the solid curve with the fitted parameter $G_s^{(y)}$. The black dashed line represents $\rho_{00}=1/3.$
Global spin alignment of $\phi$ and $K^{*0}$ vector mesons in heavy-ion collisions. The measured matrix element $\rho_{00}$ as a function of beam energy for the $\phi$ and $K^{*0}$ vector mesons within the indicated windows of centrality, transverse momentum ($p_T$) and rapidity ($y$). The open symbols indicate ALICE results for Pb+Pb collisions at 2.76 TeV at $p_{T}$ values of 2.0 and 1.4 GeV/c for the $\phi$ and $K^{*0}$ mesons, respectively, corresponding to the $p_{T}$ bin nearest to the mean $p_{T}$ for the 1.0 – 5.0 GeV/$c$ range assumed for each meson in the present analysis. The red solid curve is a fit to data in the range of $\sqrt{s_{NN}} = 19.6$ to 200 GeV, based on a theoretical calculation with a $\phi$-meson field. Parameter sensitivity of $\rho_{00}$ to the $\phi$-meson field is shown in Ref.5. The red dashed line is an extension of the solid curve with the fitted parameter $G_s^{(y)}$. The black dashed line represents $\rho_{00}=1/3.$
Example of combinatorial background subtracted invariant mass distributions and the extracted yields as a function of $\cos \theta^*$ for $\phi$ and $K^{*0}$ mesons. \textbf{a)} example of $\phi \rightarrow K^+ + K^-$ invariant mass distributions, with combinatorial background subtracted, integrated over $\cos \theta^*$; \textbf{b)} example of $K^{*0} (\overline{K^{*0}}) \rightarrow K^{-} \pi^{+} (K^{+} \pi^{-})$ invariant mass distributions, with combinatorial background subtracted, integrated over $\cos \theta^*$; \textbf{c)} extracted yields of $\phi$ as a function of $\cos \theta^*$; \textbf{d)} extracted yields of $K^{*0}$ as a function of $\cos \theta^*$.
Example of combinatorial background subtracted invariant mass distributions and the extracted yields as a function of $\cos \theta^*$ for $\phi$ and $K^{*0}$ mesons. \textbf{a)} example of $\phi \rightarrow K^+ + K^-$ invariant mass distributions, with combinatorial background subtracted, integrated over $\cos \theta^*$; \textbf{b)} example of $K^{*0} (\overline{K^{*0}}) \rightarrow K^{-} \pi^{+} (K^{+} \pi^{-})$ invariant mass distributions, with combinatorial background subtracted, integrated over $\cos \theta^*$; \textbf{c)} extracted yields of $\phi$ as a function of $\cos \theta^*$; \textbf{d)} extracted yields of $K^{*0}$ as a function of $\cos \theta^*$.
Example of combinatorial background subtracted invariant mass distributions and the extracted yields as a function of $\cos \theta^*$ for $\phi$ and $K^{*0}$ mesons. \textbf{a)} example of $\phi \rightarrow K^+ + K^-$ invariant mass distributions, with combinatorial background subtracted, integrated over $\cos \theta^*$; \textbf{b)} example of $K^{*0} (\overline{K^{*0}}) \rightarrow K^{-} \pi^{+} (K^{+} \pi^{-})$ invariant mass distributions, with combinatorial background subtracted, integrated over $\cos \theta^*$; \textbf{c)} extracted yields of $\phi$ as a function of $\cos \theta^*$; \textbf{d)} extracted yields of $K^{*0}$ as a function of $\cos \theta^*$.
Example of combinatorial background subtracted invariant mass distributions and the extracted yields as a function of $\cos \theta^*$ for $\phi$ and $K^{*0}$ mesons. \textbf{a)} example of $\phi \rightarrow K^+ + K^-$ invariant mass distributions, with combinatorial background subtracted, integrated over $\cos \theta^*$; \textbf{b)} example of $K^{*0} (\overline{K^{*0}}) \rightarrow K^{-} \pi^{+} (K^{+} \pi^{-})$ invariant mass distributions, with combinatorial background subtracted, integrated over $\cos \theta^*$; \textbf{c)} extracted yields of $\phi$ as a function of $\cos \theta^*$; \textbf{d)} extracted yields of $K^{*0}$ as a function of $\cos \theta^*$.
Efficiency corrected $\phi$-meson yields as a function of cos$\theta$* and corresponding fits with Eq.1 in the method section.
Efficiency and acceptance corrected $K^{*0}$-meson yields as a function of cos$\theta$* and corresponding fits with Eq.4 in the method section.
$\phi$-meson $\rho_{00}$ obtained from 1st- and 2nd-order event planes. The red stars (gray squares) show the $\phi$-meson $\rho_{00}$ as a function of beam energy, obtained with the 2nd-order (1st-order) EP.
$\phi$-meson $\rho_{00}$ with respect to different quantization axes. $\phi$-meson $\rho_{00}$ as a function of beam energy, for the out-of-plane direction (stars) and the in-plane direction (diamonds). Curves are fits based on theoretical calculations with a $\phi$-meson field. The corresponding $G_s^{(y)}$ values obtained from the fits are shown in the legend.
$\rho_{00}$ as a function of transverse momentum for $\phi$ for different collision energies. The gray squares and red stars are results obtained with the 1st- and 2nd-order EP, respectively.
$\rho_{00}$ as a function of transverse momentum for $\phi$ for different collision energies. The gray squares and red stars are results obtained with the 1st- and 2nd-order EP, respectively.
$\rho_{00}$ as a function of transverse momentum for $\phi$ for different collision energies. The gray squares and red stars are results obtained with the 1st- and 2nd-order EP, respectively.
$\rho_{00}$ as a function of transverse momentum for $\phi$ for different collision energies. The gray squares and red stars are results obtained with the 1st- and 2nd-order EP, respectively.
$\rho_{00}$ as a function of transverse momentum for $\phi$ for different collision energies. The gray squares and red stars are results obtained with the 1st- and 2nd-order EP, respectively.
$\rho_{00}$ as a function of transverse momentum for $\phi$ for different collision energies. The gray squares and red stars are results obtained with the 1st- and 2nd-order EP, respectively.
$\rho_{00}$ as a function of transverse momentum for $\phi$ for different collision energies. The gray squares and red stars are results obtained with the 1st- and 2nd-order EP, respectively.
$\rho_{00}$ as a function of transverse momentum for $\phi$ for different collision energies. The gray squares and red stars are results obtained with the 1st- and 2nd-order EP, respectively.
$\rho_{00}$ as a function of transverse momentum for $\phi$ for different collision energies. The gray squares and red stars are results obtained with the 1st- and 2nd-order EP, respectively.
$\rho_{00}$ as a function of transverse momentum for $\phi$ for different collision energies. The gray squares and red stars are results obtained with the 1st- and 2nd-order EP, respectively.
$\rho_{00}$ as a function of transverse momentum for $\phi$ for different collision energies. The gray squares and red stars are results obtained with the 1st- and 2nd-order EP, respectively.
$\rho_{00}$ as a function of transverse momentum for $\phi$ for different collision energies. The gray squares and red stars are results obtained with the 1st- and 2nd-order EP, respectively.
$\rho_{00}$ as a function of transverse momentum for $K^{*0}$ for different collision energies.
$\rho_{00}$ as a function of transverse momentum for $K^{*0}$ for different collision energies.
$\rho_{00}$ as a function of transverse momentum for $K^{*0}$ for different collision energies.
$\rho_{00}$ as a function of transverse momentum for $K^{*0}$ for different collision energies.
$\rho_{00}$ as a function of transverse momentum for $K^{*0}$ for different collision energies.
$\rho_{00}$ as a function of transverse momentum for $K^{*0}$ for different collision energies.
$\rho_{00}$ as a function of transverse momentum for $K^{*0}$ for different collision energies.
$\rho_{00}$ as a function of centrality for $\phi$ (upper panels) and $K^{*0}$ (lower panels). The solid squares and stars are results for the $\phi$ meson, obtained with the 1st- and 2nd-order EP, respectively. The solid circles are results for the $K^{*0}$ meson, obtained with the 2nd-order EP.}
$\rho_{00}$ as a function of centrality for $\phi$ (upper panels) and $K^{*0}$ (lower panels). The solid squares and stars are results for the $\phi$ meson, obtained with the 1st- and 2nd-order EP, respectively. The solid circles are results for the $K^{*0}$ meson, obtained with the 2nd-order EP.}
$\rho_{00}$ as a function of centrality for $\phi$ (upper panels) and $K^{*0}$ (lower panels). The solid squares and stars are results for the $\phi$ meson, obtained with the 1st- and 2nd-order EP, respectively. The solid circles are results for the $K^{*0}$ meson, obtained with the 2nd-order EP.}
$\rho_{00}$ as a function of centrality for $\phi$ (upper panels) and $K^{*0}$ (lower panels). The solid squares and stars are results for the $\phi$ meson, obtained with the 1st- and 2nd-order EP, respectively. The solid circles are results for the $K^{*0}$ meson, obtained with the 2nd-order EP.}
$\rho_{00}$ as a function of centrality for $\phi$ (upper panels) and $K^{*0}$ (lower panels). The solid squares and stars are results for the $\phi$ meson, obtained with the 1st- and 2nd-order EP, respectively. The solid circles are results for the $K^{*0}$ meson, obtained with the 2nd-order EP.}
$\rho_{00}$ as a function of centrality for $\phi$ (upper panels) and $K^{*0}$ (lower panels). The solid squares and stars are results for the $\phi$ meson, obtained with the 1st- and 2nd-order EP, respectively. The solid circles are results for the $K^{*0}$ meson, obtained with the 2nd-order EP.}
$\rho_{00}$ as a function of centrality for $\phi$ (upper panels) and $K^{*0}$ (lower panels). The solid squares and stars are results for the $\phi$ meson, obtained with the 1st- and 2nd-order EP, respectively. The solid circles are results for the $K^{*0}$ meson, obtained with the 2nd-order EP.}
Global spin alignment measurement of $\phi$ and $K^{*0}$ vector mesons in Au+Au collisions at 0-20\% centrality. The solid squares and stars are results for the $\phi$ meson, obtained with the 1st- and 2nd-order EP, respectively. The solid circles are results for $K^{*0}$-meson, obtained with the 2nd-order EP.
Global spin alignment measurement of $\phi$ and $K^{*0}$ vector mesons in Au+Au collisions at 0-20\% centrality. The solid squares and stars are results for the $\phi$ meson, obtained with the 1st- and 2nd-order EP, respectively. The solid circles are results for $K^{*0}$-meson, obtained with the 2nd-order EP.
The measurement of direct photons from Au$+$Au collisions at $\sqrt{s_{_{NN}}}=39$ and 62.4 GeV in the transverse-momentum range $0.4<p_T<3$ Gev/$c$ is presented by the PHENIX collaboration at the Relativistic Heavy Ion Collider. A significant direct-photon yield is observed in both collision systems. A universal scaling is observed when the direct-photon $p_T$ spectra for different center-of-mass energies and for different centrality selections at $\sqrt{s_{_{NN}}}=62.4$ GeV is scaled with $(dN_{\rm ch}/d\eta)^{\alpha}$ for $\alpha=1.21{\pm}0.04$. This scaling also holds true for direct-photon spectra from Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV measured earlier by PHENIX, as well as the spectra from Pb$+$Pb at $\sqrt{s_{_{NN}}}=2760$ GeV published by ALICE. The scaling power $\alpha$ seems to be independent of $p_T$, center of mass energy, and collision centrality. The spectra from different collision energies have a similar shape up to $p_T$ of 2 GeV/$c$. The spectra have a local inverse slope $T_{\rm eff}$ increasing with $p_T$ of $0.174\pm0.018$ GeV/$c$ in the range $0.4<p_T<1.3$ GeV/$c$ and increasing to $0.289\pm0.024$ GeV/$c$ for $0.9<p_T<2.1$ GeV/$c$. The observed similarity of low-$p_T$ direct-photon production from $\sqrt{s_{_{NN}}}= 39$ to 2760 GeV suggests a common source of direct photons for the different collision energies and event centrality selections, and suggests a comparable space-time evolution of direct-photon emission.
$R_{\gamma}$ for minimum bias (0-86%) Au+Au collision at $\sqrt{s_{NN}} = 62.4$ GeV (a) and $39$ GeV (b). For $62.4$ GeV also centrality bins of 0-20% (c) and 20-40% (d) are shown. Data points are shown with statistical (bar) and systematic uncertainties (box)
$R_{\gamma}$ for minimum bias (0-86%) Au+Au collision at $\sqrt{s_{NN}} = 62.4$ GeV (a) and $39$ GeV (b). For $62.4$ GeV also centrality bins of 0-20% (c) and 20-40% (d) are shown. Data points are shown with statistical (bar) and systematic uncertainties (box)
Direct photon spectra for minimum bias (0-86%) Au+Au collision at $\sqrt{s_{NN}} = 62.4$ GeV (a) and $39$ GeV (b). For $62.4$ GeV also centrality bins of 0-20% (c) and 20-40% (d) are shown. Data points are shown with statistical and systematic uncertainties, unless the central value is negative (arrows) or is consistent with zero within the statistical uncertainties (arrows with data point). In these cases upper limit with CL = 95$%$ are given.
Direct photon spectra for minimum bias (0-86%) Au+Au collision at $\sqrt{s_{NN}} = 62.4$ GeV (a) and $39$ GeV (b). For $62.4$ GeV also centrality bins of 0-20% (c) and 20-40% (d) are shown. Data points are shown with statistical and systematic uncertainties, unless the central value is negative (arrows) or is consistent with zero within the statistical uncertainties (arrows with data point). In these cases upper limit with CL = 95$%$ are given.
Inverse slopes, $T_{eff}$ , obtained from fitting the combined data from central collisions shown in Fig. 11 is compared to the fit results of the individual data sets at $\sqrt{s_{NN}} = 62.4$ GeV, $200$ GeV, and $2760$ GeV. Also included is the value for $\sqrt{s_{NN}} = 39$ GeV obtained from fitting the min. bias data set in the lower $p_T$ range.
Integrated invariant direct-photon yields vs. charged particle multiplicity for $p_{T}$ integrated from (a) 0.4 GeV/c, (b) 1.0 GeV/c, (c) 1.5 GeV/c, and (d) 2.0 to 5.0 GeV/c for all available A+A datasets.
Integrated invariant direct-photon yields vs. charged particle multiplicity for $p_{T}$ integrated from (a) 0.4 GeV/c, (b) 1.0 GeV/c, (c) 1.5 GeV/c, and (d) 2.0 to 5.0 GeV/c for all available A+A datasets.
Integrated invariant direct-photon yields vs. charged particle multiplicity for $p_{T}$ integrated from (a) 0.4 GeV/c, (b) 1.0 GeV/c, (c) 1.5 GeV/c, and (d) 2.0 to 5.0 GeV/c for all available A+A datasets.
Integrated invariant direct-photon yields vs. charged particle multiplicity for $p_{T}$ integrated from (a) 0.4 GeV/c, (b) 1.0 GeV/c, (c) 1.5 GeV/c, and (d) 2.0 to 5.0 GeV/c for all available A+A datasets.
Integrated direct-photon yields from A+A collisions for $p_{T,min}$ of $5$ GeV/c (a) and $8$ GeV/c. The representation is the same as in Fig. 13. Also shown are the results from pQCD calculations scaled by $N_{coll}$
Integrated direct-photon yields from A+A collisions for $p_{T,min}$ of $5$ GeV/c (a) and $8$ GeV/c. The representation is the same as in Fig. 13. Also shown are the results from pQCD calculations scaled by $N_{coll}$
The $\alpha$ values extracted using fits to integrated direct photon yields. The dashed line gives the average $\alpha$ value for the 4 lower $p_{T,min}$ points. Also shown is a model calculation for $\alpha$ discussed in the text.
The PHENIX collaboration presents first measurements of low-momentum ($0.4<p_T<3$ GeV/$c$) direct-photon yields from Au$+$Au collisions at $\sqrt{s_{_{NN}}}$=39 and 62.4 GeV. For both beam energies the direct-photon yields are substantially enhanced with respect to expectations from prompt processes, similar to the yields observed in Au$+$Au collisions at $\sqrt{s_{_{NN}}}$=200. Analyzing the photon yield as a function of the experimental observable $dN_{\rm ch}/d\eta$ reveals that the low-momentum ($>$1\,GeV/$c$) direct-photon yield $dN_{\gamma}^{\rm dir}/d\eta$ is a smooth function of $dN_{\rm ch}/d\eta$ and can be well described as proportional to $(dN_{\rm ch}/d\eta)^\alpha$ with $\alpha{\sim}$1.25. This new scaling behavior holds for a wide range of beam energies at the Relativistic Heavy Ion Collider and Large Hadron Collider, for centrality selected samples, as well as for different, $A$$+$$A$ collision systems. At a given beam energy the scaling also holds for high $p_T$ ($>5$\,GeV/$c$) but when results from different collision energies are compared, an additional $\sqrt{s_{_{NN}}}$-dependent multiplicative factor is needed to describe the integrated-direct-photon yield.
The extreme temperatures and energy densities generated by ultra-relativistic collisions between heavy nuclei produce a state of matter with surprising fluid properties. Non-central collisions have angular momentum on the order of 1000$\hbar$, and the resulting fluid may have a strong vortical structure that must be understood to properly describe the fluid. It is also of particular interest because the restoration of fundamental symmetries of quantum chromodynamics is expected to produce novel physical effects in the presence of strong vorticity. However, no experimental indications of fluid vorticity in heavy ion collisions have so far been found. Here we present the first measurement of an alignment between the angular momentum of a non-central collision and the spin of emitted particles, revealing that the fluid produced in heavy ion collisions is by far the most vortical system ever observed. We find that $\Lambda$ and $\overline{\Lambda}$ hyperons show a positive polarization of the order of a few percent, consistent with some hydrodynamic predictions. A previous measurement that reported a null result at higher collision energies is seen to be consistent with the trend of our new observations, though with larger statistical uncertainties. These data provide the first experimental access to the vortical structure of the "perfect fluid" created in a heavy ion collision. They should prove valuable in the development of hydrodynamic models that quantitatively connect observations to the theory of the Strong Force. Our results extend the recent discovery of hydrodynamic spin alignment to the subatomic realm.
Lambda and AntiLambda polarization as a function of collision energy. A 0.8% error on the alpha value used in the paper is corrected in this table. Systematic error bars include those associated with particle identification (negligible), uncertainty in the value of the hyperon decay parameter (2%) and reaction plane resolution (2%) and detector efficiency corrections (4%). The dominant systematic error comes from statistical fluctuations of the estimated combinatoric background under the (anti-)$\Lambda$ mass peak.
Lambda and AntiLambda polarization as a function of collision energy calculated using the new $\alpha_\Lambda=0.732$ updated on PDG2020. Systematic error bars include those associated with particle identification (negligible), uncertainty in the value of the hyperon decay parameter (2%) and reaction plane resolution (2%) and detector efficiency corrections (4%). The dominant systematic error comes from statistical fluctuations of the estimated combinatoric background under the (anti-)$\Lambda$ mass peak.
Elliptic flow (v_2) values for identified particles at midrapidity in Au + Au collisions measured by the STAR experiment in the Beam Energy Scan at the Relativistic Heavy Ion Collider at sqrt{s_{NN}}= 7.7--62.4 GeV are presented for three centrality classes. The centrality dependence and the data at sqrt{s_{NN}}= 14.5 GeV are new. Except at the lowest beam energies we observe a similar relative v_2 baryon-meson splitting for all centrality classes which is in agreement within 15% with the number-of-constituent quark scaling. The larger v_2 for most particles relative to antiparticles, already observed for minimum bias collisions, shows a clear centrality dependence, with the largest difference for the most central collisions. Also, the results are compared with A Multiphase Transport Model and fit with a Blast Wave model.
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The difference in $v_{2}$ between particles (X) and their corresponding antiparticles $\bar{X}$ (see legend) as a function of $\sqrt{s_{NN}}$ for 10%-40% central Au + Au collisions. The systematic errors are shown by the hooked error bars. The dashed lines in the plot are fits with a power-law function.
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The difference in $v_{2}$ between protons and antiprotons as a function of $\sqrt{s_{NN}}$ for 0%-10%, 10%-40% and 40%-80% central Au + Au collisions. The systematic errors are shown by the hooked error bars. The dashed lines in the plot are fits with a power-law function.
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The relative difference. The systematic errors are shown by the hooked error bars. The dashed lines in the plot are fits with a power-law function.
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The $v_{2}$ difference between protons and antiprotons (and between $\pi^{+}$ and $pi^{-}$) for 10%-40% centrality Au+Au collisions at 7.7, 11.5, 14.5, and 19.6 GeV. The $v_{2}{BBC} results were slightly shifted horizontally.
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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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected particles re plotted only for the transverse momentum range of 0.2< pT<1.6 GeV/c to emphasize the mass ordering at low p__T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected anti-particles are plotted only for the transverse momentum range of 0.2< p_T<1.6 GeV/c to emphasize the mass ordering at low p_T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected anti-particles are plotted only for the transverse momentum range of 0.2< p_T<1.6 GeV/c to emphasize the mass ordering at low p_T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected anti-particles are plotted only for the transverse momentum range of 0.2< p_T<1.6 GeV/c to emphasize the mass ordering at low p_T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected anti-particles are plotted only for the transverse momentum range of 0.2< p_T<1.6 GeV/c to emphasize the mass ordering at low p_T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected anti-particles are plotted only for the transverse momentum range of 0.2< p_T<1.6 GeV/c to emphasize the mass ordering at low p_T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected anti-particles are plotted only for the transverse momentum range of 0.2< p_T<1.6 GeV/c to emphasize the mass ordering at low p_T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected anti-particles are plotted only for the transverse momentum range of 0.2< p_T<1.6 GeV/c to emphasize the mass ordering at low p_T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected anti-particles are plotted only for the transverse momentum range of 0.2< p_T<1.6 GeV/c to emphasize the mass ordering at low p_T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected anti-particles are plotted only for the transverse momentum range of 0.2< p_T<1.6 GeV/c to emphasize the mass ordering at low p_T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected anti-particles are plotted only for the transverse momentum range of 0.2< p_T<1.6 GeV/c to emphasize the mass ordering at low p_T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected anti-particles are plotted only for the transverse momentum range of 0.2< p_T<1.6 GeV/c to emphasize the mass ordering at low p_T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected anti-particles are plotted only for the transverse momentum range of 0.2< p_T<1.6 GeV/c to emphasize the mass ordering at low p_T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected anti-particles are plotted only for the transverse momentum range of 0.2< p_T<1.6 GeV/c to emphasize the mass ordering at low p_T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected anti-particles are plotted only for the transverse momentum range of 0.2< p_T<1.6 GeV/c to emphasize the mass ordering at low p_T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected anti-particles are plotted only for the transverse momentum range of 0.2< p_T<1.6 GeV/c to emphasize the mass ordering at low p_T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected anti-particles are plotted only for the transverse momentum range of 0.2< p_T<1.6 GeV/c to emphasize the mass ordering at low p_T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected anti-particles are plotted only for the transverse momentum range of 0.2< p_T<1.6 GeV/c to emphasize the mass ordering at low p_T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected anti-particles are plotted only for the transverse momentum range of 0.2< p_T<1.6 GeV/c to emphasize the mass ordering at low p_T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected anti-particles are plotted only for the transverse momentum range of 0.2< p_T<1.6 GeV/c to emphasize the mass ordering at low p_T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected anti-particles are plotted only for the transverse momentum range of 0.2< p_T<1.6 GeV/c to emphasize the mass ordering at low p_T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected anti-particles are plotted only for the transverse momentum range of 0.2< p_T<1.6 GeV/c to emphasize the mass ordering at low p_T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected anti-particles are plotted only for the transverse momentum range of 0.2< p_T<1.6 GeV/c to emphasize the mass ordering at low p_T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected anti-particles are plotted only for the transverse momentum range of 0.2< p_T<1.6 GeV/c to emphasize the mass ordering at low p_T.
The elliptic flow, v_2 (p_T), in 0–80% central Au+Au collisions for selected anti-particles are plotted only for the transverse momentum range of 0.2< p_T<1.6 GeV/c to emphasize the mass ordering at low p_T.
The elliptic flow, v_2, of charged koans as a function of the transverse momentum,p_T,for 0–80% central Au+Au collisions.
The elliptic flow,v_2 of p, $\overline{p}$ as a function of the transverse momentum, p_T,for 0–80% central Au+Au collisions.
The elliptic flow,v_2 of p, $\overline{p}$ as a function of the transverse momentum, p_T,for 0–80% central Au+Au collisions.
The elliptic flow,v_2 of p, $\overline{p}$ as a function of the transverse momentum, p_T,for 0–80% central Au+Au collisions.
The elliptic flow,v_2 of $Omega^{-}$ and $\overline{\Omega^{+}}$ as a function of the transverse momentum, p_T,for 0–80% central Au+Au collisions.
The elliptic flow, v_2, of p and $\overline{p}$ as a function of the transverse momentum, p_T, for 0–10% central Au+Au collisions.
The elliptic flow, v_2, of p and $\overline{p}$ as a function of the transverse momentum, p_T, for 0–10% central Au+Au collisions.
The elliptic flow,v_2, of 0–80% central Au+Au collisions as a function of the reduced transverse mass,$ m_T−m_0 $, for selected particles.
The elliptic flow,v_2, of 0–80% central Au+Au collisions as a function of the reduced transverse mass,$ m_T−m_0 $, for selected particles.
The elliptic flow,v_2, of 0–80% central Au+Au collisions as a function of the reduced transverse mass,$ m_T−m_0 $, for selected particles.
The elliptic flow,v_2, of 0–80% central Au+Au collisions as a function of the reduced transverse mass,$ m_T−m_0 $, for selected anti-particles.
The difference in the v_2 values between a particle X and its corresponding anti-particle $\overline{X}$ as a function of √sNN for 0–80% central Au+Au collisions.
The difference in the v_2 values between a particle X and its corresponding anti-particle $\overline{X}$ as a function of √sNN for 0–80% central Au+Au collisions.
The difference in the v_2 values between a particle X and its corresponding anti-particle $\overline{X}$ as a function of √sNN for 0–80% central Au+Au collisions.
The difference in the v_2 values between a particle X and its corresponding anti-particle $\overline{X}$ as a function of √sNN for 0–80% central Au+Au collisions.
The difference in the v_2 values between a particle X and its corresponding anti-particle $\overline{X}$ as a function of $μ_B$ for 0–80% central Au+Au collisions.
The difference in the v_2 values between a particle X and its corresponding anti-particle $\overline{X}$ as a function of $μ_B$ for 0–80% central Au+Au collisions.
The difference in the v_2 values between a particle X and its corresponding anti-particle $\overline{X}$ as a function of $μ_B$ for 0–80% central Au+Au collisions.
The difference in the v_2 values between a particle X and its corresponding anti-particle $\overline{X}$ as a function of $μ_B$ for 0–80% central Au+Au collisions.
The inclusive $J/\psi$ transverse momentum ($p_{T}$) spectra and nuclear modification factors are reported at midrapidity ($|y|<1.0$) in Au+Au collisions at $\sqrt{s_{NN}}=$ 39, 62.4 and 200 GeV taken by the STAR experiment. A suppression of $J/\psi$ production, with respect to {\color{black}the production in $p+p$ scaled by the number of binary nucleon-nucleon collisions}, is observed in central Au+Au collisions at these three energies. No significant energy dependence of nuclear modification factors is found within uncertainties. The measured nuclear modification factors can be described by model calculations that take into account both suppression of direct $J/\psi$ production due to the color screening effect and $J/\psi$ regeneration from recombination of uncorrelated charm-anticharm quark pairs.
J/psi invariant yields in Au+Au collisions = 39 GeV as a function of pT for different centralities.
J/psi invariant yields in Au+Au collisions = 62.4 GeV as a function of pT for different centralities.
J/psi invariant yields in Au+Au collisions = 200 GeV as a function of pT for different centralities.
J/psi RCP results (with respect to 40−60% peripheral) for Au+Au collisions (39, 62.4 and 200 GeV) as a function of Npart.
J/psi RCP results for Au+Au collisions (39, 62.4 and 200 GeV) as a function of Npart.
J/psi RCP results for Au+Au collisions (39, 62.4 and 200 GeV) as a function of pT.
Exclusive photoproduction of $\rho^0(770)$ mesons is studied using the H1 detector at the $ep$ collider HERA. A sample of about 900000 events is used to measure single- and double-differential cross sections for the reaction $\gamma p \to \pi^{+}\pi^{-}Y$. Reactions where the proton stays intact (${m_Y{=}m_p}$) are statistically separated from those where the proton dissociates to a low-mass hadronic system ($m_p{<}m_Y{<}10$ GeV). The double-differential cross sections are measured as a function of the invariant mass $m_{\pi\pi}$ of the decay pions and the squared $4$-momentum transfer $t$ at the proton vertex. The measurements are presented in various bins of the photon-proton collision energy $W_{\gamma p}$. The phase space restrictions are $0.5 < m_{\pi\pi} < 2.2$ GeV, ${\vert t\vert < 1.5}$ GeV${}^2$, and ${20 < W_{\gamma p} < 80}$ GeV. Cross section measurements are presented for both elastic and proton-dissociative scattering. The observed cross section dependencies are described by analytic functions. Parametrising the $m_{\pi\pi}$ dependence with resonant and non-resonant contributions added at the amplitude level leads to a measurement of the $\rho^{0}(770)$ meson mass and width at $m_\rho = 770.8\ {}^{+2.6}_{-2.7}$ (tot) MeV and $\Gamma_\rho = 151.3\ {}^{+2.7}_{-3.6}$ (tot) MeV, respectively. The model is used to extract the $\rho^0(770)$ contribution to the $\pi^{+}\pi^{-}$ cross sections and measure it as a function of $t$ and $W_{\gamma p}$. In a Regge asymptotic limit in which one Regge trajectory $\alpha(t)$ dominates, the intercept $\alpha(t{=}0) = 1.0654\ {}^{+0.0098}_{-0.0067}$ (tot) and the slope $\alpha^\prime(t{=}0) = 0.233\ {}^{+0.067 }_{-0.074 }$ (tot) GeV${}^{-2}$ of the $t$ dependence are extracted for the case $m_Y{=}m_p$.
Elastic ($m_Y=m_p$) and proton-dissociative ($1<m_Y<10$ GeV) $\pi^{+}\pi^{-}$ photoproduction off protons, differential in the dipion mass. The tabulated cross sections are $\gamma p$ cross sections but can be converted to $ep$ cross sections using the effective photon flux $\Phi_{\gamma/e}$.
Elastic ($m_Y=m_p$) and proton-dissociative ($1<m_Y<10$ GeV) $\pi^{+}\pi^{-}$ photoproduction off protons, differential in the dipion mass --- statistical correlations coefficients $\rho_{ij}$ only. Only one half of the (symmetric) matrix is stored. Bins are identified by their global bin number.
Fit of elastic ($m_Y=m_p$) and proton-dissociative ($1<m_Y<10$ GeV) $\pi^{+}\pi^{-}$ photoproduction cross section off protons with a Soeding-inspired analytic function including $\rho$ and $\omega$ meson resonant contributions as well as a continuum background which interfere at the amplitude level. Parameters with subscript "el" and "pd" correspond to elastic and proton-dissociative cross sections, respectively.
Fit of elastic ($m_Y=m_p$) and proton-dissociative ($1<m_Y<10$ GeV) $\pi^{+}\pi^{-}$ photoproduction off protons with a Soeding-inspired analytic function --- statistical correlations only. Only one half of the (symmetric) matrix is stored.
Elastic ($m_Y=m_p$) and proton-dissociative ($1<m_Y<10$ GeV) $\pi^{+}\pi^{-}$ photoproduction off protons, differential in the dipion mass and in bins of $W$. The tabulated cross sections are $\gamma p$ cross sections but can be converted to $ep$ cross sections using the effective photon flux $\Phi_{\gamma/e}$.
Elastic ($m_Y=m_p$) and proton-dissociative ($1<m_Y<10$ GeV) $\pi^{+}\pi^{-}$ photoproduction off protons, differential in the dipion mass and in bins of $W$ --- statistical correlations coefficients $\rho_{ij}$ only. Only one half of the (symmetric) matrix is stored. Bins are identified by their global bin number.
Elastic ($m_Y=m_p$) and proton-dissociative ($1<m_Y<10$ GeV) $\rho^0(770)$ photoproduction off protons, in bins of the photon-proton energy $W$. The cross section is defined as the integral of the relativistic Breit Wigner resonance in the dipion mass over the range $2m_\pi<m_{\pi\pi}<1.53$ GeV. The tabulated cross sections are $\gamma p$ cross sections but can be converted to $ep$ cross sections using the effective photon flux $\Phi_{\gamma/e}$.
Elastic ($m_Y=m_p$) and proton-dissociative ($1<m_Y<10$ GeV) $\rho^0(770)$ photoproduction off protons in bins of the photon-proton energy $W$ --- statistical correlations coefficients $\rho_{ij}$ only. Only one half of the (symmetric) matrix is stored. Bins are identified by their global bin number.
Fit of elastic ($m_Y=m_p$) and proton-dissociative ($1<m_Y<10$ GeV) $\rho^0(770)$ photoproduction cross sections off protons as a function of energy. Parameters with subscript "el" and "pd" correspond to elastic and proton-dissociative cross sections, respectively.
Fit of elastic ($m_Y=m_p$) and proton-dissociative ($1<m_Y<10$ GeV) $\rho^0(770)$ photoproduction cross sections off protons as a function of energy --- statistical correlations coefficients $\rho_{ij}$ only. Only one half of the (symmetric) matrix is stored. Bins are identified by their global bin number.
Fit of elastic $\rho^0(770)$ photoproduction cross section off protons as a function of energy (various experiments)
Fit of elastic $\rho^0(770)$ photoproduction cross sections off protons as a function of energy (various experiments) --- statistical correlations coefficients $\rho_{ij}$ only. Only one half of the (symmetric) matrix is stored. Bins are identified by their global bin number.
Elastic ($m_Y=m_p$) and proton-dissociative ($1<m_Y<10$ GeV) $\pi^{+}\pi^{-}$ photoproduction cross section off protons, double-differential in the dipion mass and the momentum transfer $\vert t\vert$. The tabulated cross sections are $\gamma p$ cross sections but can be converted to $ep$ cross sections using the effective photon flux $\Phi_{\gamma/e}$.
Elastic ($m_Y=m_p$) and proton-dissociative ($1<m_Y<10$ GeV) $\pi^{+}\pi^{-}$ photoproduction cross section off protons, double-differential in the dipion mass and the momentum transfer $\vert t\vert$ --- statistical correlations coefficients $\rho_{ij}$ only. Only one half of the (symmetric) matrix is stored. Bins are identified by their global bin number.
Elastic ($m_Y=m_p$) and proton-dissociative ($1<m_Y<10$ GeV) $\rho^0(770)$ photoproduction off protons, single-differential in the momentum transfer $\vert t\vert$. The cross section is defined as the integral of the relativistic Breit Wigner resonance in the dipion mass over the range $2m_\pi<m_{\pi\pi}<1.53$ GeV. The tabulated cross sections are $\gamma p$ cross sections but can be converted to $ep$ cross sections using the effective photon flux $\Phi_{\gamma/e}$.
Elastic ($m_Y=m_p$) and proton-dissociative ($1<m_Y<10$ GeV) $\rho^0(770)$ photoproduction off protons, single differential in the momentum transfer $\vert t\vert$ --- statistical correlations coefficients $\rho_{ij}$ only. Only one half of the (symmetric) matrix is stored. Bins are identified by their global bin number.
Fit of elastic ($m_Y=m_p$) and proton-dissociative ($1<m_Y<10$ GeV) $\rho^0(770)$ photoproduction single-differential cross sections off protons as a function of momentum transfer $t$. Parameters with subscript "el" and "pd" correspond to elastic and proton-dissociative cross sections, respectively.
Fit of elastic ($m_Y=m_p$) and proton-dissociative ($1<m_Y<10$ GeV) $\rho^0(770)$ photoproduction single-differential cross sections off protons as a function of momentum transfer $t$ --- statistical correlations coefficients $\rho_{ij}$ only. Only one half of the (symmetric) matrix is stored. Bins are identified by their global bin number.
Elastic ($m_Y=m_p$) and proton-dissociative ($1<m_Y<10$ GeV) $\pi^{+}\pi^{-}$ photoproduction double-differenial cross section off protons, as a function of the dipion mass and the momentum transfer $\vert t\vert$, in bins of the photon-proton energy $W$ The tabulated cross sections are $\gamma p$ cross sections but can be converted to $ep$ cross sections using the effective photon flux $\Phi_{\gamma/e}$.
Elastic ($m_Y=m_p$) and proton-dissociative ($1<m_Y<10$ GeV) $\pi^{+}\pi^{-}$ photoproduction double-differenial cross section off protons, as a function of the dipion mass and the momentum transfer $\vert t\vert$, in bins of the photon-proton energy $W$ --- statistical correlations coefficients $\rho_{ij}$ only. Only one half of the (symmetric) matrix is stored. Bins are identified by their global bin number.
Elastic ($m_Y=m_p$) and proton-dissociative ($1<m_Y<10$ GeV) $\rho^0(770)$ photoproduction off protons, single-differential in the momentum transfer $\vert t\vert$, in bins of the photon-proton energy $W$. The cross section is defined as the integral of the relativistic Breit Wigner resonance in the dipion mass over the range $2m_\pi<m_{\pi\pi}<1.53$ GeV. The tabulated cross sections are $\gamma p$ cross sections but can be converted to $ep$ cross sections using the effective photon flux $\Phi_{\gamma/e}$.
Elastic ($m_Y=m_p$) and proton-dissociative ($1<m_Y<10$ GeV) $\rho^0(770)$ photoproduction cross section off protons, single differential in the momentum transfer $\vert t\vert$ and in bins of the photon-proton energy $W$ --- statistical correlations coefficients $\rho_{ij}$ only. Only one half of the (symmetric) matrix is stored. Bins are identified by their global bin number.
Regge fit of elastic ($m_Y=m_p$) and proton-dissociative ($1<m_Y<10$ GeV) $\rho^0(770)$ photoproduction single-differential cross sections off protons as a function of momentum transfer $t$ and photon-proton energy $W$. Parameters with subscript "el" and "pd" correspond to elastic and proton-dissociative cross sections, respectively.
Regge fit of elastic ($m_Y=m_p$) and proton-dissociative ($1<m_Y<10$ GeV) $\rho^0(770)$ photoproduction single-differential cross sections off protons as a function of momentum transfer $t$ and photon-proton energy $W$ --- statistical correlations coefficients $\rho_{ij}$ only. Only one half of the (symmetric) matrix is stored. Bins are identified by their global bin number.
Fit of $b$-slopes in elastic ($m_Y=m_p$) $\rho^0(770)$ photoproduction single-differential cross sections off protons as a function of momentum transfer $t$ in bins of photon-proton energy $W$.
Fit of $b$-slopes in elastic ($m_Y=m_p$) $\rho^0(770)$ photoproduction single-differential cross sections off protons as a function of momentum transfer $t$ in bins of photon-proton energy $W$ --- statistical correlations coefficients $\rho_{ij}$ only. Only one half of the (symmetric) matrix is stored. Bins are identified by their global bin number.
Fit of Pomeron trajectories in elastic ($m_Y=m_p$) $\rho^0(770)$ photoproduction single-differential cross sections off protons as a function of momentum transfer $t$ in bins of photon-proton energy $W$.
Fit of Pomeron trajectories in elastic ($m_Y=m_p$) $\rho^0(770)$ photoproduction single-differential cross sections off protons as a function of momentum transfer $t$ in bins of photon-proton energy $W$ --- statistical correlations coefficients $\rho_{ij}$ only. Only one half of the (symmetric) matrix is stored. Bins are identified by their global bin number.
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