Model Independent Tests for Time Reversal and CP Violations and for CPT Theorem in Λ_b and barΛ_b Two Body Decays

Weak decays of beauty baryons like \Lambda_b (\bar\Lambda_b) into \Lambda (\bar\Lambda) and V (J^P = 1^-), where both decay products are polarized, offer interesting opportunities to perform tests of time reversal and CP violations and of CPT invariance. We propose a model independent parametrization of the angular distribution and of the polarization of the final resonances, by means of the spin density matrix. The transverse component of the polarization is sensitive to time reversal violations, moreover CP-and CPT-sensitive observables are defined.