Yields and elliptic flow of $d(\bar{d})$ and $^{3}He(\bar{^{3}He})$ in Au+Au collisions at $\sqrt{s_{_{NN}}} =$ 200 GeV

Abstract

We present the $p_{T}$ spectra, elliptic flow ($v_2$) and coalescence parameters $B_{2}$ for $d$, $\bar{d}$ ($1<p_{T}<4$ GeV/c) and $B_{3}$ for $^{3}He$, $\bar{^{3}He}$ ($2<p_{T}<6$ GeV/c) produced at mid-rapidity in Au+Au col lisions at $\sqrt{s_{_{NN}}} = 200$ GeV. The results are measured in the STAR experiment at RHIC. The spectra of the light nuclei show softer $p_T$ distributions than calculations from a blast-wave model in which the parameters were fixed from pion, kaon and proton $v_2$($p_T$) and $p_T$ distributions. The coalescence volume is found to track with pion HBT re sults for different collision geometries. The $v_2$ measurement for $d(\overline{d})$ as a function of transverse momentum $p_T$ is found to follow an approximate atomic mass number ($A$) scaling while that of $^{3}He(\bar{^{3}He}) $ deviates slightly from the scaling. A negative $v_{2}$ has been observed for $\bar{d}$ at low $p_{T}$, consiste nt with large radial flow in Au+Au collisions.