A CP sensitive asymmetry in the three-body decay t̃1→bν̃ττ+

We consider the three-body decay t̃1→bν̃ττ+ and propose the asymmetry of the τ polarization perpendicular to the decay plane as a CP sensitive observable. We calculate this asymmetry in the Minimal Supersymmetric Standard Model with the parameters μ and At complex. In the parameter domain where the decay t̃1→bν̃ττ+ is important this asymmetry can go up to ±30%. We also estimate the event rates necessary to observe this asymmetry at 90% CL.