Sizable time-reversal violating effects in bottom baryon decays

Abstract

We study time-reversal (T) asymmetries in the charmless two-body decays of antitriplet bottom baryons. We find that in Bb → BnP with Bb = ($$ {\Xi}_b^{-} $$ Ξ b − ,$$ {\Xi}_b^0 $$ Ξ b 0 , Λb) and Bn(P) a octet baryon (pseudoscalar meson), the positive and negative helicity amplitudes are both sizable, resulting in the large T-violating effects. Particularly, the T-odd parameters, βw, for the color-enhanced channels are expected to be around −40% and 25% in b → s and b → d transitions for the standard model, which can be measured by the experiments at LHCb, respectively. On the other hand, in Bb → BnV(γ) with V(γ) a vector meson (photon), the decays are predominated by a single helicity amplitude, and the T violating effects by the correlations among spins are suppressed. We also explore the T violating observables for the Ξb decays based on the angular distributions.

Center of mass motion in bag model

“…The homogeneous bag model, first proposed in Ref. [26], has been widely applied in various decay systems [27][28][29][30]. It is meant to reconcile the Poincaré symmetry and the bag model without necessarily introducing a new parameter.…”