The $Ï(1020)\rightarrow e^{+}e^{-}$ meson decay measured with the STAR experiment in Au+Au collisions at $\sqrt{s_{_{NN}}}$ = 200 GeV
arXiv:1503.04217
Abstract
We report the measurement of the leptonic ($e^{+}e^{-}$) decay channel of the $Ï$(1020) meson in Au+Au collisions at $\sqrt{s_{_{NN}}}$ = 200 GeV by the STAR experiment. The transverse momentum ($p_{\rm T}$) spectrum is measured for 0.1 $\le p_{\rm T} \le 2.5$ GeV/$c$ at mid-rapidity ($|y|\le1$). We obtain the $p_{\rm T}$-integrated $Ï$(1020) mass $M_Ï=1017.7\pm0.8 (\rm {stat.}) \pm0.9 (\rm {sys.})$ MeV/$c^{2}$ and width $Î_Ï = 8.0\pm 2.5(\rm {stat.}) \pm 2.3(\rm {sys.}) \textrm{MeV/}c^{2}$, which are within 1.5\,$Ï$ and 1.1\,$Ï$ of the vacuum values, respectively. No significant difference is observed in the measured $p_{\rm T}$ spectrum, $dN/dy$, or $\left<p_{\rm T}\right>$ of the $Ï$(1020) meson between the $e^{+}e^{-}$ and hadronic ($K^{+}K^{-}$) decay channels as measured by the same experiment. The experimental results are compared to a theoretical model including medium-modified $Ï$(1020).