Nuclear modification factor of isolated photons in PbPb collisions at $\sqrt{s_{_{\mathrm{NN}}}} = 5.02~\mathrm{TeV}$

The transverse energy ($E^{\gamma}_\text{T}$) spectra and the nuclear modification factors ($R_{\mathrm{AA}}$) of isolated photons are analyzed using proton-proton (pp) and lead-lead (PbPb) collisions at $\sqrt{s_{_{\mathrm{NN}}}} = 5.02~\mathrm{TeV}$. The data were collected using the CMS detector at the CERN LHC with corresponding integrated luminosities of $404~\mu\mathrm{b}^{-1}$ and $27.4~\mathrm{pb}^{-1}$ for PbPb and pp data, respectively. The results are shown as a function of photon $E^{\gamma}_\text{T}$ in the pseudorapidity range $\left\lvert{\eta}\right\rvert < 1.44$, for $E^{\gamma}_\text{T}$ between 25 and 200$~\mathrm{GeV}$ and for different centrality bins. The data are compared to JEPHOX next-to-leading-order calculations and found to be in good agreement. In addition, $R_{\mathrm{AA}}$ is consistent with unity for all centralities in PbPb.