Speaker
Description
We present the semi-inclusive measurement of charged jets recoiling from direct-photon and $\pi^0$ triggers in central Au+Au collisions at $\sqrt{s_\mathrm{NN}}=200$ GeV, using a dataset with integrated luminosity 13 nb$^{-1}$ recorded by the STAR experiment in 2014. The photon and $\pi^0$ triggers have $9<\rm E_{T}^{trig}<20$ GeV. Charged jets are reconstructed with the anti-$\rm{k_{T}}$ algorithm with resolution parameters R=0.2 and 0.5. A Mixed Event technique developed previously by STAR is used to correct the recoil jet yield for uncorrelated background, enabling recoil jet measurements over a broad $\rm p_{T,jet}$ range with large jet radius. We report the corrected semi-inclusive recoil jet yields for both triggers and compare them to those for p+p collisions. These measurements have different trigger bias, in terms of both the path-length distribution and quark/gluon mix of the recoil jet population, and their corrected recoil spectra are compared. We also report the recoil jet azimuthal distribution relative to the $\pi^0$ trigger axis, and search for medium-induced modifications. Such modifications may probe the quasi-particle nature of the Quark-Gluon Plasma and help discriminate different models of it.
