  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.
