Constraints on theWRmass andCPviolation in left-right models

Abstract

We update the constraints on the right-handed W{sub R} gauge boson mass, mixing angle {zeta} with the left-handed W{sub L} gauge boson, and other parameters in general left-right symmetric models with different mechanisms of CP violation. Constraints mostly independent of any assumption on the quark sector are obtained from a reanalysis of muon decay data. The best {chi}{sup 2} fit of the data gives g{sub R}/g{sub L}=0.94{plus_minus}0.09 for the ratio of right to left gauge couplings, with M{sub W{sub R}}{ge}485 GeV and {vert_bar}{zeta}{vert_bar}{le}0.0327. Fixing g{sub L}=g{sub R} (in particular for manifestly left-right symmetric models), we obtain M{sub W{sub R}}{approx_gt}549 GeV and {vert_bar}{zeta}{vert_bar}{approx_gt}0.0333. Estimates of the left-right hadronic matrix elements in the neutral kaon system and their uncertainties are revised using large N{sub c} and chiral perturbation theory arguments. With explicitly given assumptions on the long-distance ({Delta}S=1){sup 2} contributions to the K{sub L}-K{sub S} mass difference, lower bounds on M{sub W{sub R}} are obtained. With the same assumptions, one also gets strong upper bounds from the CP-violating parameter {epsilon}{sub K}, for most of the parameter space of left-right models where the right-handed third family does not contribute in CP-violating quantities. For manifestly left-right symmetric models the lower bound obtained is M{submore » W{sub R}}{approx_gt}(1.6{sub {minus}0.7}{sup +1.2}) TeV. {copyright} {ital 1997} {ital The American Physical Society}« less