Testing Time-Reversal: Lambda_b Decays into Polarized Resonances

Weak decays of beauty baryons like Lambda_b into Lambda V(J^P=1^-), where the produced resonances are polarized, offer interesting opportunity to perform tests of Time-Reversal Invariance. This paper emphasizes the particular role of the resonance polarization-vectors and their physical properties by symmetry transformations. In particular, it is shown that the normal component of a polarization-vector, as defined in the Jackson's frame, is Lorentz invariant and could get large values, notably in the case of J/psi production.