CP violation in tbW couplings at the LHC

TL;DR

This paper investigates potential CP-violating effects in top-bottom-W couplings at the LHC, proposing asymmetries to detect new physics signatures with feasible sensitivity at 14 TeV.

Contribution

It introduces model-independent CP-violating asymmetries based on top decay variables to probe anomalous tbW couplings at the LHC.

Findings

CP-violating couplings can be probed at the percent level

Asymmetries involving polarization and decay angles are effective

Feasible detection at 14 TeV with 10 fb^{-1} luminosity

Abstract

We study in a model-independent way anomalous CP-violating tbW effective couplings that might arise from new physics in the processes pp-> tW^- X and pp-> tbar W^+X, followed by semileptonic decay of t and tbar. These processes have a dependence on effective tbW couplings both in the production process as well as in the decay of the t or tbar. We propose several CP-violating asymmetries constructed out of variables in the two processes, including t and tbar polarization, and energy and azimuthal angles of the decay particles. We find that it is feasible to probe a certain CP-violating combination of anomalous couplings at the per cent level at the LHC for centre-of-mass energy 14 TeV and an integrated luminosity of 10 fb^{-1}.