Exclusive production of π+π− and π0π0 pairs in photon-photon and in ultrarelativistic heavy ion collisions

The γγ → π π reactions are discussed. To describe those processes, we include dipion continuum, resonances, high-energy pion-pion rescatterings, ρ meson exchange and pQCD Brodsky-Lepage mechanisms. The cross section for the production of pion pairs in photon-photon collisions in peripheral heavy ion collisions is calculated with the help of Equivalent Photon Approximaption (EPA) in the impact parameter space. We show predictions at √s NN TeV which could be measured e.g. by the ALICE collaboration at the LHC.