T-odd asymmetry in W + jet events at the LHC.
W bosons produced at high transverse momentum in hadron collisions can have polarization along the direction perpendicular to the production plane, which is odd under naïve T reversal where both the three-momenta and angular momenta are reversed. Perturbative QCD predicts nonzero polarization at the one-loop level, which can be measured as parity-odd components in the angular distribution of charged leptons from the decay of W bosons. We perform a detector-level simulation with the generator MadGraph5_aMC@NLO, and demonstrate that the asymmetry can be observed at the 8 TeV LHC with 20 fb(-1) of data. If confirmed, it will be the first experimental measurement of the sign of the imaginary part of one-loop QCD amplitudes.
PH Department, TH Unit, CERN, CH-1211 Geneva 23, Switzerland.
Rikkert
R
Frederix
KEK Theory Center and SOKENDAI, 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan.
Kaoru
K
Hagiwara
Department of Physics and Center for Mathematics and Theoretical Physics, National Central University, Chungli, Taiwan 32001, Republic of China.
Toshifumi
T
Yamada
Department of Physics, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan.
Hiroshi
H
Yokoya