Light-by-light scattering in ultraperipheral PbPb collisions at the Large Hadron Collider

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We calculate cross sections for diphoton production in (semi)exclusive PbPb collisions, relevant for the LHC. The calculation is based on equivalent photon approximation in the impact parameter space. The cross sections for elementary γγ→ γγ subprocess are calculated including two different mechanisms. We take into account box diagrams with leptons and quarks in the loops. In addition, we consider a vector-meson dominance (VDM-Regge) contribution with virtual intermediate hadronic (vector-like) excitations of the photons. We get much higher cross sections in PbPb collisions than in earlier calculation from the literature. This opens a possibility to study the γγ→ γγ (quasi)elastic scattering at the LHC. We present many interesting differential distributions which could be measured by the ALICE, CMS or ATLAS Collaborations at the LHC. We study whether a separation or identification of different components (boxes, VDM-Regge) is possible. We find that the cross section for elastic γγ scattering could be measured in the heavy-ion collisions for subprocess energies smaller than Wᵧᵧ ≈ 15-20 GeV.