A measurement of W gamma and Z gamma production in proton-proton collisions at root s = 7 TeV is presented. Results are based on a data sample recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 36 pb(-1). The electron and muon decay channels of the W and Z are used. The total cross sections are measured for photon transverse energy E(T)(gamma) > 10 GeV and spatial separation from charged leptons in the plane of pseudorapidity and azimuthal angle Delta R(l.gamma) > 0.7, and with an additional dilepton invariant mass requirement of M(ll) > 50 GeV for the Z gamma process. The following cross section times branching fraction values are found: sigma(pp -> W gamma + X) x B(W -> lv) = 56.3 +/- 5.0(stat.) +/- 5.0(syst.) +/- 2.3(lumi.) pb and sigma(pp -> Z gamma + X) x B(Z -> ll) = 9.4 +/- 1.0(stat.) +/- 0.6(syst.) +/- 0.4(lumi.) pb. These measurements are in agreement with standard model predictions. The first limits on anomalous WW gamma, ZZ gamma, and Z gamma gamma trilinear gauge couplings at root s = 7 TeV are set.
Measurement of W gamma and Z gamma production in pp collisions at root s=7 TeV
AMAPANE, Nicola Carlo;ARGIRO', Stefano;BOTTA, CRISTINA;CASTELLO, Roberto;COSTA, Marco;MIGLIORE, Ernesto;MONACO, Vincenzo;MUSICH, MARCO;OBERTINO, Maria Margherita;PELLICCIONI, Mario;ROMERO, Alessandra;SACCHI, Roberto;SOLA, VALENTINA;SOLANO, Ada Maria;P. Meridiani;BELLAN, Riccardo;COVARELLI, Roberto;
2011-01-01
Abstract
A measurement of W gamma and Z gamma production in proton-proton collisions at root s = 7 TeV is presented. Results are based on a data sample recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 36 pb(-1). The electron and muon decay channels of the W and Z are used. The total cross sections are measured for photon transverse energy E(T)(gamma) > 10 GeV and spatial separation from charged leptons in the plane of pseudorapidity and azimuthal angle Delta R(l.gamma) > 0.7, and with an additional dilepton invariant mass requirement of M(ll) > 50 GeV for the Z gamma process. The following cross section times branching fraction values are found: sigma(pp -> W gamma + X) x B(W -> lv) = 56.3 +/- 5.0(stat.) +/- 5.0(syst.) +/- 2.3(lumi.) pb and sigma(pp -> Z gamma + X) x B(Z -> ll) = 9.4 +/- 1.0(stat.) +/- 0.6(syst.) +/- 0.4(lumi.) pb. These measurements are in agreement with standard model predictions. The first limits on anomalous WW gamma, ZZ gamma, and Z gamma gamma trilinear gauge couplings at root s = 7 TeV are set.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.