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A systematic study is presented for centrality, transverse momentum ($p_T$) and pseudorapidity ($eta$) dependence of the inclusive charged hadron elliptic flow ($v_2$) at midrapidity($|eta| < 1.0$) in Au+Au collisions at $sqrt{s_{NN}}$ = 7.7, 11.5, 19.6, 27 and 39 GeV. The results obtained with different methods, including correlations with the event plane reconstructed in a region separated by a large pseudorapidity gap and 4-particle cumulants ($v_2{4}$), are presented in order to investigate non-flow correlations and $v_2$ fluctuations. We observe that the difference between $v_2{2}$ and $v_2{4}$ is smaller at the lower collision energies. Values of $v_2$, scaled by the initial coordinate space eccentricity, $v_{2}/varepsilon$, as a function of $p_T$ are larger in more central collisions, suggesting stronger collective flow develops in more central collisions, similar to the results at higher collision energies. These results are compared to measurements at higher energies at the Relativistic Heavy Ion Collider ($sqrt{s_{NN}}$ = 62.4 and 200 GeV) and at the Large Hadron Collider (Pb + Pb collisions at $sqrt{s_{NN}}$ = 2.76 TeV). The $v_2(p_T)$ values for fixed $p_T$ rise with increasing collision energy within the $p_T$ range studied ($< 2 {rm GeV}/c$). A comparison to viscous hydrodynamic simulations is made to potentially help understand the energy dependence of $v_{2}(p_{T})$. We also compare the $v_2$ results to UrQMD and AMPT transport model calculations, and physics implications on the dominance of partonic versus hadronic phases in the system created at Beam Energy Scan (BES) energies are discussed.
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
We present STAR measurements of strange hadron ($mathrm{K}^{0}_{mathrm S}$, $Lambda$, $overline{Lambda}$, $Xi^-$, $overline{Xi}^+$, $Omega^-$, $overline{Omega}^+$, and $phi$) production at mid-rapidity ($|y| < 0.5$) in Au+Au collisions at $sqrt{s_{_{
The STAR Collaboration presents new measurements of inclusive charged hadron distributions for $p_{T} <$ 12 GeV/c from Au+Au collisions at $sqrt{s_{NN}}$ = 200 GeV. Charged hadron suppression at high $p_{T}$ is similar in shape and magnitude at all c
We present measurements of electrons and positrons from the semileptonic decays of heavy-flavor hadrons at midrapidity ($|y|<$ 0.35) in Au$+$Au collisions at $sqrt{s_{_{NN}}}=62.4$ GeV. The data were collected in 2010 by the PHENIX experiment that in
The STAR Collaboration at the Relativistic Heavy Ion Collider reports the first measurement of inclusive jet production in peripheral and central Au+Au collisions at $sqrt{s_{NN}}$=200 GeV. Jets are reconstructed with the anti-k$_{T}$ algorithm using