Azimuthal anisotropy in high-energy heavy-ion collisions at RHIC energies

Directed and elliptic event anisotropy parameters measured in the experiments at relativistic heavy-ion collider are presented. The possible origin of the measured elliptic anisotropy parameter $v_2$ and its sensitivity to the early phase of the high-energy heavy-ion collisions are discussed.Comment: 6 pages, 6 figures, Proceedings 20th Winter Workshop on Nuclear Dynamics, Trelawny Beach, Jamaica, March 15--20, 200

Away-side asymmetry of jet correlation relative to reaction plane: a sensitive probe for jet in-medium modifications

We proposed a new observable based on two particle azimuth correlation to study the away-side medium response in mid-central Au+Au collisions. We argue that a left/right asymmetry may appear at the away-side by selecting triggers separately in the left and right side of the reaction plane. A simple model estimation suggests that the magnitude of such asymmetry could reach 30% with details depends on the medium response mechanisms. This asymmetry, if observed, can help to distinguish competing theoretical models.Comment: 4 pages and 5 figures, update to published versio

Ratio of baryon and electric-charge cumulants at second order with acceptance corrections

We evaluate the ratio of baryon and electric-charge cumulants at second order from the recent experimental results at $\sqrt{s_{_{NN}}}=200$ GeV by the STAR Collaboration. The baryon number cumulant is reconstructed from the proton number distribution, and effects of the finite acceptance on the transverse momentum are corrected assuming the independent particle emission. We show that the obtained ratio has a dependence on the rapidity window. Comparison of the result with the hadron resonance gas model and lattice QCD numerical simulations suggests that if the fluctuations are generated from a thermal medium its temperature is significantly lower than the chemical freezeout temperature.Comment: 6 pages, 3 figure

Identified charged particle azimuthal anisotropy in PHENIX at RHIC

We present here v$_2$ of identified and inclusive charged particles measured in the PHENIX central arm detector ($|\eta| < 0.35$) with respect to the reaction plane defined at $|\eta| = 3 \sim 4$ in 200 GeV Au+Au collisions. We find that v$_2$ increases from central to mid-central collisions reaching a maximum at about 50% of the geometric cross section and then decreases again for more peripheral collisions. As a function of transverse momentum in minimum-bias collisions, the v$_2$ parameter increases linearly with p$_{\rm T}$ up to p$_{\rm T}$ $\simeq$ 2 GeV/c and then saturates for inclusive charged particles. The v$_2$ parameter of identified particles ($\pi^+$, $\pi^-$, $K^+$, $K^-$, $p$ and $\bar{p}$) follow a hydro-dynamic behavior up to 2 GeV/c in p$_{\rm T}$, where the lighter mass particles have larger v$_2$ at a given p$_{\rm T}$. However there is an indication that this trend is reversed at around p$_{\rm T}$ $\simeq$ 2 GeV/c, where $p$ and $\bar{p}$ have larger v$_2$ than $\pi$ and $K$.Comment: 4 pages, 4 figures. Talk presented at Quark Matter 2002, Nantes, France, July 18-24, 2002. To appear in the proceedings (Nucl. Phys. A