Single electron yields from semileptonic charm and bottom hadron decays in Au$+$Au collisions at $\sqrt{s_{NN}}=200$ GeV

TL;DR

This paper reports the first measurement of the relative contributions of charm and bottom hadrons to electrons from semileptonic decays in Au+Au collisions at 200 GeV, revealing different suppression patterns for charm and bottom quarks.

Contribution

It introduces the use of the PHENIX silicon vertex detector for precision displaced tracking to distinguish charm and bottom contributions in heavy-ion collisions.

Findings

Electrons from bottom hadrons are less suppressed than those from charm in the 3-4 GeV/c pT range.

The bottom electron fractions in Au+Au are similar to those in p+p collisions at the same energy.

The study provides separate R_AA measurements for charm and bottom decay electrons.

Abstract

The PHENIX Collaboration at the Relativistic Heavy Ion Collider has measured open heavy-flavor production in minimum bias Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV via the yields of electrons from semileptonic decays of charm and bottom hadrons. Previous heavy-flavor electron measurements indicated substantial modification in the momentum distribution of the parent heavy quarks due to the quark-gluon plasma created in these collisions. For the first time, using the PHENIX silicon vertex detector to measure precision displaced tracking, the relative contributions from charm and bottom hadrons to these electrons as a function of transverse momentum are measured in Au$+$Au collisions. We compare the fraction of electrons from bottom hadrons to previously published results extracted from electron-hadron correlations in $p$$+$$p$ collisions at $\sqrt{s_{_{NN}}}=200$ GeV and find the fractions to be similar within the large uncertainties on both measurements for $p_T>4$ GeV/$c$. We use the bottom electron fractions in Au$+$Au and $p$$+$$p$ along with the previously measured heavy flavor electron $R_{AA}$ to calculate the $R_{AA}$ for electrons from charm and bottom hadron decays separately. We find that electrons from bottom hadron decays are less suppressed than those from charm for the region $3<p_T<4$ GeV/$c$.