High $p_{T}$ inclusive hadron and photon spectra in pp and PbPb collisions

Abstract

In this article, we report the inclusive charged hadron and isolated photon spectra at $\sqrt{s_{NN}}=2.76$ TeV PbPb collisions measured with the CMS detector at LHC. Charged particle momentum spectra are compared to a constructed reference measurement of proton-proton collisions at $\sqrt{s}=2.76$ TeV by using a combination of $x_T$ scaling and direct interpolation at fixed $p_{T}$. Photon results are compared to next to leading order calculations at the same center of mass energy. Nuclear modification factors ($R_{AA}$) are calculated to study the properties of the medium. While a large suppression is observed in the charged particle $R_{AA}$ at high transverse momentum, isolated photons show no modifications, revealing that PbPb collisions at $\sqrt{s_{NN}}=2.76$ TeV produce a strongly interacting colored medium.