T-odd observables from anomalous tbW couplings in single-top production at an ep collider

Abstract

We investigate the possibility that an imaginary anomalous tbW coupling can be measured in the process e−p→νet‾X by means of T-odd observables. One such observable considered here is the polarization of the top antiquark transverse to the production plane. The other is a T-odd correlation constructed out of observable momenta when the top quark decays leptonically. Both these T-odd observables are shown to be proportional to the imaginary part of only one of the tbW anomalous couplings, the other couplings giving either vanishing or negligible contribution. This imaginary part could signal either a CP-odd coupling, or an absorptive part in the effective coupling, or both. We estimate the 1-σ limits that might be derived in the case of each of these observables for a collider with a proton energy of 7 TeV and an electron energy of 60 GeV and also in the case of a higher electron energy of 150 GeV.