Nuclear Modification of Electron Spectra and Implications for Heavy Quark Energy Loss inAu+AuCollisions atsNN=200GeV

The PHENIX experiment has measured midrapidity ($|\eta |<0.35$) transverse momentum spectra ($0.4<p_T<5.0\mathrm{GeV}/c$) of electrons as a function of centrality in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=200\mathrm{GeV}$. Contributions from photon conversions and from light hadron decays, mainly Dalitz decays of ${\pi }^0$ and $\eta$ mesons, were removed. The resulting nonphotonic electron spectra are primarily due to the semileptonic decays of hadrons carrying heavy quarks. Nuclear modification factors were determined by comparison to nonphotonic electrons in $p+p$ collisions. A significant suppression of electrons at high $p_T$ is observed in central $\mathrm{Au}+\mathrm{Au}$ collisions, indicating substantial energy loss of heavy quarks.