Lepton pair production through two photon process in heavy ion collisions

This paper investigates the electromagnetic production of lepton pairs with lowtotal transverse momentum in relativistic heavy-ion collisions. We estimate the initial photons' transverse momentum contributions by employing models where the average transversemomentumsquared of the incoming photon can be calculated in the equivalent photon approximation. We further derive an all order QED resummation for the soft photon radiation, which gives an excellent description of theATLASdata in ultraperipheral collisions at the LHC. For peripheral and central collisions, additional p(T)-broadening effects frommultiple interactions with the medium and the magnetic field contributions from the quark-gluon plasma are also discussed.