CP violation in tbW couplings at the LHC

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→t¯W+X, followed by semileptonic decay of t and t¯. These processes have a dependence on effective tbW couplings both in the production process as well as in the decay of the t or t¯. We propose several CP-violating asymmetries constructed out of variables in the two processes, including t and t¯ 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 percent level at the LHC for centre-of-mass energy 14 TeV and an integrated luminosity of 10 fb−1.