Tracing CP violation in the production of top quark pairs by multiple TeV proton-proton collisions

Abstract

We investigate the possibilities of searching for non-standard CP violation in $pp\to t\bar{t}X$ at multiple TeV collision energies. A general kinematic analysis of the underlying partonic production processes $gg\to t\bar{t}$ and $q\bar{q}\to t\bar{t}$ in terms of their density matrices is given. We evaluate the CP-violating parts of these matrices in two-Higgs doublet extensions of the standard model (SM) and give results for CP asymmetries at the parton level. We show that these asymmetries can be traced by measuring suitable observables constructed from energies and momenta of the decay products of $t$ and $\bar{t} $. We find CP-violating effects to be of the order of $10^{-3}$ and show that possible contaminations induced by SM interactions are savely below the expected signals.