Eur. Phys. J. C 70, 1017-1024 (2010)
https://doi.org/10.1140/epjc/s10052-010-1501-5

CP violating asymmetry in stop decay into bottom and chargino

Institute of High Energy Physics, Austrian Academy of Sciences, 1050, Vienna, Austria

frank@hephy.oeaw.ac.at

Received: 22 June 2010
Revised: 5 November 2010
Published online: 26 November 2010

Abstract

In the MSSM with complex parameters, loop corrections to the decay of a stop into a bottom quark and a chargino can lead to a CP violating decay rate asymmetry. We calculate this asymmetry at full one-loop level and perform a detailed numerical study, analyzing the dependence on the parameters and complex phases involved. If the stop can decay into a gluino, the self-energy and the vertex correction dominate due to the strong coupling. It is shown that the vertex contribution is always suppressed. We therefore give a simple approximate formula for the asymmetry. We account for the constraints on the parameters coming from several experimental limits. Asymmetries up to 25 percent are obtained. We also comment on the feasibility of measuring this asymmetry at the LHC.