The $\varphi (1020)\to e^{+}{e}^{-}$ meson decay measured with the STAR experiment in Au+Au collisions at $\sqrt{s_{{}_{NN}}}$ = 200 GeV

Abstract

We report the measurement of the leptonic ($e^{+}{e}^{-}$) decay channel of the $\varphi$(1020) meson in Au+Au collisions at $\sqrt{s_{{}_{NN}}}$ = 200 GeV by the STAR experiment. The transverse momentum ($p_{\mathrm{T}}$) spectrum is measured for 0.1 $\le p_{\mathrm{T}}\le 2.5$ GeV/$c$ at mid-rapidity ($|y|\le 1$). We obtain the $p_{\mathrm{T}}$-integrated $\varphi$(1020) mass $M_{\varphi }=1017.7\pm 0.8(stat.)\pm 0.9(sys.)$ MeV/$c^2$ and width ${\Gamma }_{\varphi }=8.0\pm 2.5(stat.)\pm 2.3(sys.)\text{MeV/}{\mathrm{c}}^2$, which are within 1.5\,$\sigma$ and 1.1\,$\sigma$ of the vacuum values, respectively. No significant difference is observed in the measured $p_{\mathrm{T}}$ spectrum, $dN/dy$, or $⟨p_{\mathrm{T}}⟩$ of the $\varphi$(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 $\varphi$(1020).