We present measurements of $\Omega$ and $\phi$ production at mid-rapidity from Au+Au collisions at nucleon-nucleon center-of-mass energies $\sqrt{s_{NN}}$ = 7.7, 11.5, 19.6, 27 and 39 GeV by the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). Motivated by the coalescence formation mechanism for these strange hadrons, we study the ratios of $N(\Omega^{-}+\Omega^{+})/(2N(\phi))$. These ratios as a function of transverse momentum ($p_T$) fall on a consistent trend at high collision energies, but start to show deviations in peripheral collisions at $\sqrt{s_{NN}}$ = 19.6, 27 and 39 GeV, and in central collisions at 11.5 GeV in the intermediate $p_T$ region of 2.4-3.6 GeV/c. We further evaluate empirically the strange quark $p_T$ distributions at hadronization by studying the $\Omega/\phi$ ratios scaled by the number of constituent quarks. The NCQ-scaled $\Omega/\phi$ ratios show a suppression of strange quark production in central collisions at 11.5 GeV compared to $\sqrt{s_{NN}} >= 19.6$ GeV. The shapes of the presumably thermal strange quark distributions in 0-60% most central collisions at 7.7 GeV show significant deviations from those in 0-10% most central collisions at higher energies. These features suggest that there is likely a change of the underlying strange quark dynamics in the transition from quark-matter to hadronic matter at collision energies below 19.6 GeV.
Phi Meson Spectra.
Phi Meson Spectra.
Phi Meson Spectra.
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.
Efficiency corrected cumulants of net-charge distributions as a function of $\langle N_{part} \rangle$ from Au+Au collisions at different collision energies.
Efficiency corrected cumulants of net-charge distributions as a function of $\langle N_{part} \rangle$ from Au+Au collisions at different collision energies.
Efficiency corrected cumulants of net-charge distributions as a function of $\langle N_{part} \rangle$ from Au+Au collisions at different collision energies.
The PHENIX experiment has measured $\phi$ meson production in $d$$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV using the dimuon and dielectron decay channels. The $\phi$ meson is measured in the forward (backward) $d$-going (Au-going) direction, $1.2
Invariant yields of $\phi$ meson production as a function of $p_T$ at different $d$+Au centrality classes. Type B represents uncertainties that are correlated from point to point.
Invariant yields of $\phi$ meson production as a function of $p_T$ at different $d$+Au centrality classes. Type B represents uncertainties that are correlated from point to point.
Invariant yields of $\phi$ meson production as a function of $p_T$ at different $d$+Au centrality classes. Type B represents uncertainties that are correlated from point to point.
Balance functions have been measured in terms of relative pseudorapidity ($\Delta \eta$) for charged particle pairs at the Relativistic Heavy-Ion Collider (RHIC) from Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 7.7 GeV to 200 GeV using the STAR detector. These results are compared with balance functions measured at the Large Hadron Collider (LHC) from Pb+Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV by the ALICE Collaboration. The width of the balance function decreases as the collisions become more central and as the beam energy is increased. In contrast, the widths of the balance functions calculated using shuffled events show little dependence on centrality or beam energy and are larger than the observed widths. Balance function widths calculated using events generated by UrQMD are wider than the measured widths in central collisions and show little centrality dependence. The measured widths of the balance functions in central collisions are consistent with the delayed hadronization of a deconfined quark gluon plasma (QGP). The narrowing of the balance function in central collisions at $\sqrt{s_{\rm NN}}$ = 7.7 GeV implies that a QGP is still being created at this relatively low energy.
The balance function in terms of $\Delta \eta$ for all charged particles with $0.2 < p_{T} < 2.0$ GeV/$c$ from central Au+Au collisions (0-5%) for $\sqrt{s_{NN}}=7.7$ GeV. The data are the measured balance functions corrected by subtracting balance functions calculated using mixed events. Also shown are balance functions calculated using shuffled events.
The balance function in terms of $\Delta \eta$ for all charged particles with $0.2 < p_{T} < 2.0$ GeV/$c$ from central Au+Au collisions (0-5%) for $\sqrt{s_{NN}}=11.5$ GeV. The data are the measured balance functions corrected by subtracting balance functions calculated using mixed events. Also shown are balance functions calculated using shuffled events.
The balance function in terms of $\Delta \eta$ for all charged particles with $0.2 < p_{T} < 2.0$ GeV/$c$ from central Au+Au collisions (0-5%) for $\sqrt{s_{NN}}=19.6$ GeV. The data are the measured balance functions corrected by subtracting balance functions calculated using mixed events. Also shown are balance functions calculated using shuffled events.
We present high precision measurements of elliptic flow near midrapidity ($|y|<1.0$) for multi-strange hadrons and $\phi$ meson as a function of centrality and transverse momentum in Au+Au collisions at center of mass energy $\sqrt{s_{NN}}=$ 200 GeV. We observe that the transverse momentum dependence of $\phi$ and $\Omega$ $v_{2}$ is similar to that of $\pi$ and $p$, respectively, which may indicate that the heavier strange quark flows as strongly as the lighter up and down quarks. This observation constitutes a clear piece of evidence for the development of partonic collectivity in heavy-ion collisions at the top RHIC energy. Number of constituent quark scaling is found to hold within statistical uncertainty for both 0-30$\%$ and 30-80$\%$ collision centrality. There is an indication of the breakdown of previously observed mass ordering between $\phi$ and proton $v_{2}$ at low transverse momentum in the 0-30$\%$ centrality range, possibly indicating late hadronic interactions affecting the proton $v_{2}$.
No description provided.
No description provided.
No description provided.
We present the first measurement of elliptic ($v_2$) and triangular ($v_3$) flow in high-multiplicity $^{3}$He$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV. Two-particle correlations, where the particles have a large separation in pseudorapidity, are compared in $^{3}$He$+$Au and in $p$$+$$p$ collisions and indicate that collective effects dominate the second and third Fourier components for the correlations observed in the $^{3}$He$+$Au system. The collective behavior is quantified in terms of elliptic $v_2$ and triangular $v_3$ anisotropy coefficients measured with respect to their corresponding event planes. The $v_2$ values are comparable to those previously measured in $d$$+$Au collisions at the same nucleon-nucleon center-of-mass energy. Comparison with various theoretical predictions are made, including to models where the hot spots created by the impact of the three $^{3}$He nucleons on the Au nucleus expand hydrodynamically to generate the triangular flow. The agreement of these models with data may indicate the formation of low-viscosity quark-gluon plasma even in these small collision systems.
Results for $v_2$ and $v_3$ as a function of $p_T$ for inclusive charged hadrons at midrapidity in 0-5% central $^3$He+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV.
In Phys. Lett. B 753, 629-638 (2016) [arXiv:1507.08188] the BESIII collaboration published a cross section measurement of the process $e^+e^-\to \pi^+ \pi^-$ in the energy range between 600 and 900 MeV. In this erratum we report a corrected evaluation of the statistical errors in terms of a fully propagated covariance matrix. The correction also yields a reduced statistical uncertainty for the hadronic vacuum polarization contribution to the anomalous magnetic moment of the muon, which now reads as $a_\mu^{\pi\pi\mathrm{, LO}}(600 - 900\,\mathrm{MeV}) = (368.2 \pm 1.5_{\rm stat} \pm 3.3_{\rm syst})\times 10^{-10}$. The central values of the cross section measurement and of $a_\mu^{\pi\pi\mathrm{, LO}}$, as well as the systematic uncertainties remain unchanged.
Bare cross section $\sigma^\mathrm{bare}(e^+e^-\to\pi^+\pi^-(\gamma_\mathrm{FSR}))$ of the process $e^+e^-\to\pi^+\pi^-$ measured using the initial state radiation method. The data is corrected concerning final state radiation and vacuum polarization effects. The final state radiation is added using the Schwinger term at born level.
Statistical covariance matrix of the bare cross section $\sigma^\mathrm{bare}(e^+e^-\to\pi^+\pi^-(\gamma_\mathrm{FSR}))$.
Pion form factor $|F_\pi|^2$ measured using the initial state radiation method. The data is corrected concerning vacuum polarization effects.
The PHENIX Collaboration at the Relativistic Heavy Ion Collider has measured open heavy-flavor production in minimum bias Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV via the yields of electrons from semileptonic decays of charm and bottom hadrons. Previous heavy-flavor electron measurements indicated substantial modification in the momentum distribution of the parent heavy quarks due to the quark-gluon plasma created in these collisions. For the first time, using the PHENIX silicon vertex detector to measure precision displaced tracking, the relative contributions from charm and bottom hadrons to these electrons as a function of transverse momentum are measured in Au$+$Au collisions. We compare the fraction of electrons from bottom hadrons to previously published results extracted from electron-hadron correlations in $p$$+$$p$ collisions at $\sqrt{s_{_{NN}}}=200$ GeV and find the fractions to be similar within the large uncertainties on both measurements for $p_T>4$ GeV/$c$. We use the bottom electron fractions in Au$+$Au and $p$$+$$p$ along with the previously measured heavy flavor electron $R_{AA}$ to calculate the $R_{AA}$ for electrons from charm and bottom hadron decays separately. We find that electrons from bottom hadron decays are less suppressed than those from charm for the region $3
Bottom and charm hadron invariant yields as a function of $p_{T}$.
Bottom hadron fraction with respect to heavy flavor electron as a function of $p_{T}$.
Bottom and charm hadron $R_{AA}$ as a function of $p_{T}$.
We present measurements of $e^+e^-$ production at midrapidity in Au$+$Au collisions at $\sqrt{s_{_{NN}}}$ = 200 GeV. The invariant yield is studied within the PHENIX detector acceptance over a wide range of mass ($m_{ee} <$ 5 GeV/$c^2$) and pair transverse momentum ($p_T$ $<$ 5 GeV/$c$), for minimum bias and for five centrality classes. The \ee yield is compared to the expectations from known sources. In the low-mass region ($m_{ee}=0.30$--0.76 GeV/$c^2$) there is an enhancement that increases with centrality and is distributed over the entire pair \pt range measured. It is significantly smaller than previously reported by the PHENIX experiment and amounts to $2.3\pm0.4({\rm stat})\pm0.4({\rm syst})\pm0.2^{\rm model}$ or to $1.7\pm0.3({\rm stat})\pm0.3({\rm syst})\pm0.2^{\rm model}$ for minimum bias collisions when the open-heavy-flavor contribution is calculated with {\sc pythia} or {\sc mc@nlo}, respectively. The inclusive mass and $p_T$ distributions as well as the centrality dependence are well reproduced by model calculations where the enhancement mainly originates from the melting of the $\rho$ meson resonance as the system approaches chiral symmetry restoration. In the intermediate-mass region ($m_{ee}$ = 1.2--2.8 GeV/$c^2$), the data hint at a significant contribution in addition to the yield from the semileptonic decays of heavy-flavor mesons.
Cocktail of hadronic sources for the 2010 run using the PYTHIA generator for the open heavy flavor contributions.
Invariant mass spectrum of $e^+e^-$ pairs in MB Au+Au collisions within the PHENIX acceptance compared to the cocktail of expected decays.
$Au collisions at $\sqrt{s_{NN}}$=200 GeV recorded in 2008 with the PHENIX detector at the Relativistic Heavy Ion Collider. Jets are reconstructed using the $R=0.3$ anti-$k_{t}$ algorithm from energy deposits in the electromagnetic calorimeter and charged tracks in multi-wire proportional chambers, and the jet transverse momentum ($p_T$) spectra are corrected for the detector response. Spectra are reported for jets with $12
Measured anti-$k_T$, $R$ = 0.3 jet yields in $d$+Au collisions, and the measured and calculated jet cross section in $p$+$p$ collisions.
$R_{dAu}$ as a function of $p_T$.
$R_{CP}$ as a function of $p_T$.
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