We have performed the first measurement of the coherent Ï(2S) photo-production cross section in ultra-peripheral Pb. Pb collisions at the LHC. This charmonium excited state is reconstructed via the Ï(2S)âl+l- and Ï(2S)âJ/ÏÏ+Ï- decays, where the J/Ï decays into two leptons. The analysis is based on an event sample corresponding to an integrated luminosity of about 22 μb-1. The cross section for coherent Ï(2S) production in the rapidity interval -0.9<y<0.9 is dÏÏ(2S)coh/dy=0.83±0.19(stat+syst) mb. The Ï(2S) to J/Ï coherent cross section ratio is 0.34-0.07+0.08(stat+syst). The obtained results are compared to predictions from theoretical models.
Coherent Psi(2S) photo-production in ultra-peripheral PbPb collisions at sqrt(sNN)=2.76 TeV
DE CARO, ANNALISA;DE GRUTTOLA, DANIELE;DE PASQUALE, Salvatore;FUSCO GIRARD, Mario;MENINNO, ELISA;PAGANO, PAOLA;VIRGILI, Tiziano;CALIVA', Alberto
2015
Abstract
We have performed the first measurement of the coherent Ï(2S) photo-production cross section in ultra-peripheral Pb. Pb collisions at the LHC. This charmonium excited state is reconstructed via the Ï(2S)âl+l- and Ï(2S)âJ/ÏÏ+Ï- decays, where the J/Ï decays into two leptons. The analysis is based on an event sample corresponding to an integrated luminosity of about 22 μb-1. The cross section for coherent Ï(2S) production in the rapidity interval -0.9I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.