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The cross section for exclusive production of $\pi^+ \pi^-$ and $\pi^0 \pi^0$meson pairs in ultrarelativistic heavy ion collisions is calculated for LHCenergy $\sqrt{s_{NN}} =$ 3.5 TeV taking into account photon-photon mechanism.We concentrate on the production of large two-pion invariant masses where themechanism of the elementary $\gamma \gamma \to \pi \pi$ process is not fullyunderstood. In order to include a size of nuclei we perform calculation in theimpact-parameter equivalent photon approximation (EPA). Realistic chargedensities are used to calculate charged form factor of $^{208}$Pb nucleus andto generate photon fluxes associated with ultrarelativistic heavy ions.Sizeable cross sections are obtained that can be measured at LHC. The crosssection for elementary $\gamma \gamma \to \pi \pi$ is calculated in theframework of pQCD Brodsky-Lepage (BL) mechanism with the distribution amplitudeused to descibe recent data of the BABAR collaboration on pion transition formfactor, using hand-bag mechanism advocated to describe recent Belle data aswell as $t$ and $u$-channel meson/reggeon exchanges. We present distributionsin two-pion invariant mass as well as the pion pair rapidity for the nuclearprocess.

Exclusive production of large invariant mass pion pairs in ultraperipheral ultrarelativistic heavy ion collisions