New CP observables in B degrees(t)-> hyperon+antihyperon from parity violation in the sequential decay - art. no. 114021

We consider the decay B-0(t) --> hyperon+antihyperon, followed by hyperon w eak decay. We show that parity violation in the latter allows us to reach n ew CP observables: not only Im lambda(f) but also Re lambda(f) can be measu red. In the decay B-d(0)(t) --> Lambda<(Lambda)over bar> (BR similar to 10( -6)), Lambda --> p pi(-) these observables reduce to sin 2 alpha and cos 2 alpha in the small penguin limit, the latter solving the discrete ambiguity alpha --> pi/2 - alpha. For beta one could consider the Cabibbo suppressed mode B-d(0)(t) --> Lambda(c)(+)Lambda(c)(+) (BR similar to 10(-4)), Lambda (c)(+) --> Lambda pi(+), p (K) over bar(0), ... (with BR similar to 10(-2)) . The pure penguin modes B-s(0)(t) --> Sigma(-)Sigma(-), Xi(-)Xi(-), Omega( -)Omega(-) (BR similar to 10(-7)) can be useful in the search of CP violati on beyond the standard model. Because of the small total rates, the study o f these modes could only be done in future high statistics experiments. Als o, in the most interesting case Lambda<(Lambda)over bar> the time dependenc e of the asymmetry can be difficult to reconstruct. On the other hand, we s how that Ed mesons, being a coherent source of Lambda<(Lambda)over bar>, ar e useful to look for CP violation in Lambda decay. We also discuss B-d(0)(t ) --> J/psi K*(0) --> l(+)l(-) K-s pi(0) where the secondary decays conserv e parity, and angular correlations allow us to determine terms of the form cos delta cos 2 beta, delta being a strong phase. This phase has been measu red by CLEO, but we point out that a discrete ambiguity prevents us from de termining sgn(cos 2 beta). However, if one assumes small strong phases, lik e in factorization and as supported by CLEO data, one could have informatio n on sgn(cos 2 beta). Similar remarks can be made for cos 2 alpha in the de cay B-d(0)(t) --> rho rho --> 4 pi. [S0556-2821(98)03121-X].