Relativistic description of the $\Xi_b$ baryon semileptonic decays

Semileptonic decays of the $\Xi_b$ baryon are studied in the framework of the relativistic quark-diquark model based on the quasipotential approach. The weak decay form factors are calculated with the comprehensive account of all relativistic effects without employing nonrelativistic and heavy quark expansions. On this basis differential and total decay rates as well as different asymmetry parameters are calculated for the heavy-to-heavy $\Xi_b\to \Xi_c\ell\nu_\ell$ and heavy-to-light $\Xi_b\to \Lambda\ell\nu_\ell$ semileptonic decays. Predictions for the ratios of such decays involving $\tau$ lepton and muon are presented.