A first measurement of the polarization of W bosons with large transverse momenta in pp collisions is presented. The measurement is based on 36 pb-1 of data recorded at √s=7 TeV by the CMS detector at the LHC. The left-handed, right-handed, and longitudinal polarization fractions (fL, fR, and f0, respectively) of W bosons with transverse momenta larger than 50 GeV are determined by using decays to both electrons and muons. The muon final state yields the most precise measurement: (fL-fR)-=0.240±0.036(stat)±0.031(syst) and f0-=0.183±0.087(stat)±0.123(syst) for negatively charged W bosons and (fL-fR)+=0.310±0.036(stat)±0.017(syst) and f0+=0.171±0.085(stat)±0.099(syst) for positively charged W bosons. This establishes, for the first time, that W bosons produced in pp collisions with large transverse momenta are predominantly left-handed, as expected in the standard model.
Measurement of the Polarization of W Bosons with Large Transverse Momenta in W+jets Events at the LHC
TOSI, SILVANO;
2011-01-01
Abstract
A first measurement of the polarization of W bosons with large transverse momenta in pp collisions is presented. The measurement is based on 36 pb-1 of data recorded at √s=7 TeV by the CMS detector at the LHC. The left-handed, right-handed, and longitudinal polarization fractions (fL, fR, and f0, respectively) of W bosons with transverse momenta larger than 50 GeV are determined by using decays to both electrons and muons. The muon final state yields the most precise measurement: (fL-fR)-=0.240±0.036(stat)±0.031(syst) and f0-=0.183±0.087(stat)±0.123(syst) for negatively charged W bosons and (fL-fR)+=0.310±0.036(stat)±0.017(syst) and f0+=0.171±0.085(stat)±0.099(syst) for positively charged W bosons. This establishes, for the first time, that W bosons produced in pp collisions with large transverse momenta are predominantly left-handed, as expected in the standard model.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.