Coherent ψ(2S) photo-production in ultra-peripheral PbPb collisions at sNN=2.76 TeV

We have performed the first measurement of the coherent ψ(2S)ψ(2S) photo-production cross section in ultra-peripheral PbPb collisions at the LHC. This charmonium excited state is reconstructed via the ψ(2S)→l+l−ψ(2S)→l+l− and ψ(2S)→J/ψπ+π−ψ(2S)→J/ψπ+π− decays, where the J/ψJ/ψ decays into two leptons. The analysis is based on an event sample corresponding to an integrated luminosity of about 22 μb−122 μb−1. The cross section for coherent ψ(2S)ψ(2S) production in the rapidity interval −0.9