CP violation in $H^\pm t$ production at the LHC

TL;DR

This paper investigates CP violation effects in charged Higgs production with a top quark at the LHC, calculating asymmetries at next-to-leading order in the MSSM and analyzing their magnitudes.

Contribution

It provides the first detailed numerical analysis of CP violating asymmetries in $pp o tH^d + X$ at the LHC within the MSSM framework.

Findings

Production asymmetry is approximately 20%.

Decay asymmetry in $H^d$ can reach about 12%.

Asymmetries are mainly due to gluino-mediated box graphs.

Abstract

We study effects of CP violation in the associated production of a charged Higgs boson and a top quark at the LHC, $pp \to tH^\pm + X$. 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 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 $t b$, $\nu_\tau \tau^\pm$ and $W h^0$. In the case with $H^\pm \to t b$ decay, mainly due to CP violating box graphs with gluino, the asymmetry can go up to $\sim$ 12%.