CP violation in associated production of a charged Higgs boson and a top quark at the LHC

Abstract

We study effects of CP violation in an associated production of a charged Higgs boson and a top quark at the LHC: $pp\to t{H}^{\pm }+X$. We calculate the CP violating asymmetry between the total cross section for $H^{+}$ and $H^{-}$ production at next-to-leading order in the MSSM, and perform a detailed numerical analysis. In the production only the asymmetry is of the order of 20%. The asymmetry in the production and any subsequent decay of an on-shell charged Higgs boson is to a good approximation the sum of the asymmetry in the production and the asymmetry in the decay. We consider subsequent decays of $H^{\pm }$ to $tb$, ${\nu }_{\tau }{\tau }^{\pm }$ and $W{h}^0$. In the case of subsequent $H^{\pm }\to tb$ decay, the $W^{\pm }-H^{\pm }$ self energy contributions from the production and the decay cancel. However, the remaining effect, mainly due to CP violating box graphs with gluino can go up to $\sim 13$%.

Comments: Contributed talk, given at the workshop "Prospects for Charged Higgs Discovery at Colliders", September 16-19 2008, Uppsala, Sweden, 6 pages, 5 figures. To appear in the proceedings of the workshop, sign corrected in the box graph contribution