Rapidity distributions are presented for events containing either a Z boson or a photon with a single jet in proton-proton collisions produced at the CERN LHC. The data, collected with the CMS detector at √s = 7 TeV, correspond to an integrated luminosity of 5.0 inverse femtobarns. The individual rapidity distributions of the boson and the jet are consistent within 5% with expectations from perturbative QCD. However, QCD predictions for the sum and the difference in rapidities of the two final-state objects show discrepancies with CMS data. In particular, next-to-leading-order QCD calculations, and two common Monte Carlo event generators using different methods to match matrix-element partons with parton showers, appear inconsistent with the data as well as with each other.
Rapidity distributions in exclusive Z + jet and γ + jet events in pp collisions at √s=7 TeV
BONACORSI, DANIELE;BRAIBANT, SYLVIE;BRIGLIADORI, LUCA;CAMPANINI, RENATO;CAPILUPPI, PAOLO;CASTRO, ANDREA;CODISPOTI, GIUSEPPE;CUFFIANI, MARCO;FANFANI, ALESSANDRA;FASANELLA, DANIELE;GUIDUCCI, LUIGI;MENEGHELLI, MARCO;PRIMAVERA, FEDERICA;ROVELLI, TIZIANO;SIROLI, GIAN PIERO;TOSI, NICOLÒ;
2013
Abstract
Rapidity distributions are presented for events containing either a Z boson or a photon with a single jet in proton-proton collisions produced at the CERN LHC. The data, collected with the CMS detector at √s = 7 TeV, correspond to an integrated luminosity of 5.0 inverse femtobarns. The individual rapidity distributions of the boson and the jet are consistent within 5% with expectations from perturbative QCD. However, QCD predictions for the sum and the difference in rapidities of the two final-state objects show discrepancies with CMS data. In particular, next-to-leading-order QCD calculations, and two common Monte Carlo event generators using different methods to match matrix-element partons with parton showers, appear inconsistent with the data as well as with each other.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.