Wuppertal 2015 – scientific programme

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T: Fachverband Teilchenphysik

T 98: Soft QCD und PDF fits

T 98.8: Talk

Thursday, March 12, 2015, 18:30–18:45, K.11.20 (K5)

Determination of the absolute LHC luminosity with photon-photon collisions during the pPb run @ 5.02TeV with CMS — •Melike Akbiyik, Sebastian Baur, Colin Baus, Igor Katkov, Alaa Metwaly, and Ralf Ulrich — Institute of Experimental nuclear Physics (IEKP), Karlsruhe,Germany

Di-muon production in photon-photon collisions is a benchmark process that allow for the precise determination of the luminosity at LHC. In Particular in collisions, where at least one of the nuclei is a lead nucleus, the photon fluxes are large enough to make efficient use of it. CMS has, for example, measured the total inelastic proton-lead cross-section by detecting activitiy in the forward calorimeters. For this measurement the luminosity determination is based on van der Meer scans, which is cross checked here with di-muons.

In this analysis di-muon production during the pPb run in 2013 is measured and the absolute LHC luminosity determined. The exclusivity of di-muon photoproduction events is determined from the number of charged tracks and additional hits in the calorimeters. In particular the theforward calorimeters CASTOR and ZDC are very useful for this purpose. The efficiency of the trigger event selection and reconstruction is studied in detail