We present elliptic flow, $v_2$, measurements for charged and identified particles at midrapidity in Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7, 11.5 and 39 GeV at STAR. We compare the inclusive charged hadron $v_2$ to those from high energies at RHIC ($\sqrt{s_{NN}}$ = 62.4 and 200 GeV), at LHC ($\sqrt{s_{NN}}$ = 2.76 TeV). A significant difference in $v_2$ between baryons and anti-baryons is observed and the difference increases with decreasing beam energy. We observed the $v_2$ of $ϕ$ meson is systematically lower than other particles in Au+Au collisions at $\sqrt{s_{NN}}$ = 11.5 GeV.
In this contribution we report $e^{+}e^{-}$ spectra with various invariant mass and p$_{T}$ differentials in Au$+$Au collisions at $\sqrt{s_{NN}}$=200 GeV and U$+$U collisions at $\sqrt{s_{NN}}$=193 GeV. The structure of the t ($t\approx p^2_{\mathrm{T}}$) distributions of these mass regions will be shown and compared with the same distributions in ultra-peripheral collisions. Additionally, this contribution discusses first measurements of $μ^{+}μ^{-}$ invariant mass spectra from STAR's recently installed Muon Telescope Detector (MTD) in p$+$p and Au$+$Au collisions at $\sqrt{s_{NN}}$ = 200 Ge…
We present STAR's measurement of the $e^{+}e^{-}$ continuum as a function of centrality, invariant mass, and transverse momentum for U+U collisions at $\sqrt{s_{NN}}$ = 193 GeV. Also reported are the acceptance-corrected $e^{+}e^{-}$ invariant mass spectra for minimum-bias Au+Au collisions at $\sqrt{s_{NN}}$ = 27, 39, and 62.4 GeV and U+U collisions at $\sqrt{s_{NN}}$ = 193 GeV. The connection between the integrated $e^{+}e^{-}$ excess yields normalized by charge particle multiplicity ($dN_{ch}/dy$) at mid-rapidity and the lifetime of the fireball is discussed.
We present recent results from Al(beam)+Au(target) collisions at $\sqrt{s_{NN}}=4.9$ GeV and Au+Au collisions at $\sqrt{s_{NN}}=4.5$\kern 0.16667em GeV from the STAR fixed-target (FXT) program. We report transverse mass spectra of protons, $K^0_S$ and $Λ$, rapidity density distributions of $π^\pm$, $K^0_S$ and $Λ$, directed flow of protons, $π^\pm$, $K^0_S$ and $Λ$, and elliptic flow of protons and $π^{\pm}$. These are the first measurements of pion directed and elliptic flow in this energy range at RHIC. Pion and proton elliptic flow show mass ordering. Measurements are compared with the publ…
Measurements of direct photon production in p+Pb and p+C collisions at $\sqrt{s_\mathrm{NN}} = 17.4\mathrm{GeV}$ are presented. Upper limits on the direct photon yield as a function of $p_\mathrm{T}$ are derived and compared to the results for Pb+Pb collisions at $\sqrt{s_\mathrm{NN}} = 17.3$ GeV. The production of the $η$ meson, which is an important input to the direct photon signal extraction, has been determined in the $η\rightarrow 2γ$ channel for p+C collisions at $\sqrt{s_\mathrm{NN}} = 17.4\mathrm{GeV}$.
The phase diagram of strongly interacting matter can be explored by analyzing data of heavy-ion collisions at different center of mass collision energies. For investigating the space-time structure of the hadron emission source, HBT correlation measurements are among the best tools. In this paper we present the latest results from the RHIC PHENIX experiment on such measurements in $\sqrt{s_{\rm NN}}=$ 39 GeV and 62 GeV Au+Au collisions.
In this paper we present the study of the azimuthal correlation function of non-photonic electrons with low-pT hadrons produced in Cu+Cu collision at sqrt(s_NN)=200 GeV measured by STAR experiment at RHIC. Possible modification of the awayside peak is observed.
We report on the pT dependence of nuclear modification factors ($R_{CP}$) for Ks, Lambda, Xi and the Anti-Lambda/Ks ratios at mid-rapidity from Au+Au collisions at \sqrt{s_{NN}} = 39, 11.5 and 7.7 GeV. At \sqrt{s_{NN}} = 39 GeV, the $R_{CP}$ data shows a baryon/meson separation at intermediate pT and a suppression for Ks for pT up to 4.5 GeV/$c$; the Anti-Lambda/Ks shows baryon enhancement in the most central collisions. However, at \sqrt{s_{NN}} = 11.5 and 7.7 GeV, $R_{CP}$ shows much less baryon/meson separation and Anti-Lambda/Ks shows almost no baryon enhancement. These observations indica…
We investigate modification of the bottom quark production due to cold nuclear matter effects (CNM) at mid-rapidity in d+Au collisions at $\sqrt{s_{NN}} = 200$ GeV at RHIC. Our results indicate that bottom production is not suppressed due to CNM effects in those collisions. We also found that shadowing and initial $k_T$ breadboarding for charm quarks explains at low $p_T$ ($p_T < 3$ GeV/c) the enhancement of heavy flavor decay electron yield in d+Au collisions at $\sqrt{s_{NN}} = 200$ GeV compared to p+p.
We present the measurements of D0, D+, D*+ meson v_2 as well as D0 R_{AA} in different directions with respect to the estimated reaction plane in Pb-Pb collisions at sqrt(s_{NN)) = 2.76 TeV with the ALICE detector at the LHC.
During RHIC 2010 run, STAR has collected a large amount of minimum-bias, central and high $p_{T}$ trigger data in Au+Au collisions at $\sqrt{s_{NN}} = 39$, 62.4 and 200 GeV with detector configuration for minimum photonic conversion background. In this article we report on a new high precision measurement of non-photonic electron mid-rapidity invariant yield, improved nuclear modification factor and $v_{2}$ in Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV. We also present measurements of mid-rapidity invariant yield at $\sqrt{s_{NN}} = 62.4$ and $v_{2}$ at $\sqrt{s_{NN}} = 39$ and 62.4 GeV.
The measurement of J/{psi} azimuthal anisotropy is presented as a function of transverse momentum for different centralities in Au+Au collisions at {sqrt{s_{NN}}} = 200 GeV. The measured J/{psi} elliptic flow is consistent with zero within errors for transverse momentum between 2 and 10 GeV/c. Our measurement suggests that J/{psi} with relatively large transverse momentum are not dominantly produced by coalescence from thermalized charm quarks, when comparing to model calculations.
We present preliminary results of Non-Photonic Electron (NPE) production, NPE-hadron azimuthal correlation as well as NPE elliptic flow studies at midrapidity using a data set with high statistics and low photon conversion background from $Au+Au$ collisions at $\sqrt {S_{NN}} = 200$ GeV collected at RHIC in Run 2010.
The study of charm production in heavy-ion collisions is considered an excellent probe for the properties of the hot and dense medium created in heavy-ion collisions. Measurements of D-meson nuclear modification can provide strong constraints into the mechanisms of in-medium energy loss and charm flow in the medium. The measurement of $D^0$ elliptic flow in pPb collisions helps us understand the strength of charm quarks coupling to significantly reduced systems which demonstrate hydrodynamic properties. In this paper, the measurements of the $D^0$ nuclear modification factor in PbPb collisions…
Different regions on the QCD phase diagram can be investigated by varying the collision energy and the centrality in heavy-ion collisions. In our latest measurements at the PHENIX experiment at RHIC, we utilize Lévy-type sources to describe the measured HBT correlation functions. In this paper we report the current status of the analysis of the centrality and beam energy dependence of the Lévy source parameters in Au+Au collisions from $\sqrt{s_{NN}}$ = 15 GeV to $\sqrt{s_{NN}}$ = 200 GeV.
We present the ALICE results on the nuclear modification factor and elliptic flow of electrons and muons from open heavy-flavour hadron decays at mid-rapidity and forward rapidity in Pb--Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 and 5.02 TeV for different centrality intervals. The results are compared to model calculations that include interactions of heavy quarks with the medium.
We report preliminary results of hypertriton observation in heavy-ion collisions at RHIC. We have identified 157 +- 30 candidates in the current sample containing ~10^8 Au+Au events at \sqrt{s_{NN}} = 200 GeV. The production rate of hypertriton is close to that of helium 3. No extra penalty factor is observed for hypertriton, in contrast to results observed at the AGS.
The di-electron analysis for 200 GeV p+p collisions is presented in this article. The cocktail simulations of di-eletrons from light flavor meson decays and heavy flavor decays are reported and compared with data. The perspectives for di-lepton measurements in Au+Au collisions are discussed.
In this proceedings, we present our first measurements of $ϕ$ meson and $Ξ^-$ hyperon production in Au+Au collisions at $\sqrt{s_{NN}}$ = 3 GeV. Various models including thermal and transport model calculations are compared to data, these results imply that the matter produced in the 3 GeV Au+Au collisions is considerably different from that at higher energies.
We present $ΛΛ$ correlation measurements in heavy-ion collisions for Au+Au collisions at $\sqrt{s_{NN}}= 200$ GeV using the STAR experiment at the Relativistic Heavy-Ion Collider (RHIC). The Lednický-Lyuboshitz analytical model has been used to fit the data to obtain a source size, a scattering length and an effective range. Implications of the measurement of the $ΛΛ$ correlation function and interaction parameters for di-hyperon searches are discussed.
Collective flow reflects dynamical evolution in high-energy heavy ion collisions. In particular, the strange hadron elliptic flow reflects early collision dynamics. We present results from a systematic analysis of the centrality dependence of strange hadron elliptic flow ($v_2$) measurement of $K_{S}^{0}$, $Λ$ and $Ξ$ for Cu + Cu collisions at 200 GeV. Results for Cu + Cu collisions are compared with results previously reported for Au + Au collisions. We will also compare our data with results from ideal hydrodynamic calculations.
Event anisotropy of identified $π^{0}$, photon and electron compared to charged $π$, $K$, $p$ and deuteron in $\sqrt{s_{NN}}$ = 200 GeV Au+Au at PHENIX
We present a calculation of the elliptic flow of electrons from beauty-hadron decays in semi-central Pb--Pb collisions at centre-of-mass energy per colliding nucleon pair, represented as $\sqrt{s_{\rm NN}}$, of 2.76 TeV. The result is obtained by the subtraction of the charm quark contribution in the elliptic flow of electrons from heavy-flavour hadron decays in semi-central Pb--Pb collisions at \snn = 2.76 TeV recently made publicly available by the ALICE collaboration.
We present preliminary results from D^0 meson measurements through the hadronic decay channel in minimum bias Au+Au collisions at \sqrt{s_{NN}} = 200 GeV at STAR. The measurements are performed using a secondary vertexing technique that exploits the resolution given by the Silicon detectors available in STAR.
Three-dimensional source images for mid-rapidity, low transverse momentum kaon and pion pairs have been extracted from central Au+Au collisions data at \sqrt{s_{NN}} = 200 GeV by the STAR experiment at RHIC. The pion source function displays significant non-Gaussian features implying a finite pion emission duration. On the other hand, the kaon source function is essentially Gaussian, consistent with instantaneous emission from the fireball.
Elliptic flow of Lambda hyperons in Pb+Pb collisions at 158A GeV
在CERN-SPS的NA 49合作组中，测量了158 AGeV半中心Pb+Pb碰撞中λ超子的椭圆流.使用将粒子与事件平面相关联的标准方法。测量V2近中快度的报告作为一个功能的快速性，中心性和横向动量。Lambda粒子的椭圆流随着碰撞参量和横向动量的增加而增加。它是比较与V2的π介子和质子，以及与模型计算。显著的椭圆流和它的质量依赖性的观察表明强烈的集体行为的重核碰撞已经在SPS产生的物质。在158 A GeV能量下，对不同粒子种类的椭圆流的标度特性进行了测试。数据的pT范围有限，无法对聚结模型进行决定性检验。
