Measurements of direct-photon production in Pb–Pb collisions at √sNN= 5.02 TeV and √sNN= 2.76 TeV with the ALICE experiment

Recent results on direct-photon measurements in Pb--Pb collisions at √sNN = 5.02 TeV from central to peripheral collisions, as well as in 0--10% central and 20--40% semicentral Pb--Pb collisions at √sNN = 2.76 TeV with improved significance are presented. A significant direct-photon signal is measured for pT 2 GeV/c from central to peripheral Pb--Pb collisions at √sNN = 5.02 TeV which is in agreement with model calculations containing pre-equilibrium photons in the intermediate pT range and prompt photons at high pT. No significant direct-photon signal is measured in the low pT interval which is also in agreement with the small thermal-photon signal predicted by state-of-the art models. On the other hand, a direct-photon signal is measured for pT $>$ 1 GeV/c with a significance of 3.1 (1.0 $<$ pT $<$ 1.8 GeV/c) and 3.4 (1.0 $<$ pT $<$ 2.3 GeV/c) in 0--10% and 20--40% central Pb--Pb collisions at √sNN = 2.76 TeV, respectively. Direct photons at both energies are in agreement with state-of-the-art theory calculations over the complete pT range and measured centralities.