Search

We reanalyze the Λ b → p transition form factors in the perturbative QCD (PQCD) approach by including higher-twist light-cone distribution amplitudes (LCDAs) of a Λ b baryon and a proton. The previous PQCD evaluation performed decades ago with only the leading-twist Λ b baryon and proton LCDAs gave the form factors, which are two orders of magnitude smaller than indicated by experimental data. We find that the twist-4 Λ b baryon LCDAs and the twist-4 and -5 proton LCDAs contribute dominantly, and the enhanced form factors become consistent with those from lattice QCD and other nonperturbative methods. The estimated branching ratios of the semileptonic decays Λ b → p ℓ ν ¯ ℓ and the hadronic decay Λ b → p π are also close to the data. It implies that the b quark mass is not really heavy enough, and higher-power contributions play a crucial role, similar to the observation made in analyses of B meson transition form factors. With the formalism established in this work, we are ready to study various exclusive heavy baryon decays systematically in the PQCD approach. [ABSTRACT FROM AUTHOR]

After the discovery of the double-charm baryon Ξ cc + + by LHCb, one of the most important topics is to search for the bottom-charm baryons which contain a b quark, a c quark and a light quark. In this work, we study the two-body non-leptonic weak decays of a bottom-charm baryon into a spin-1/2 bottomed baryon and a light pseudoscalar meson with the short-distance contributions calculated under the factorization hypothesis and the long-distance contributions considering the final-state-interaction effects. The branching fractions of all fifty-seven decay channels are estimated. The results indicate that Ξ bc + → Ξ b 0 π + , Ξ bc 0 → Ξ b - π + and Ω bc 0 → Ω b - π + decay modes have relatively large decay rates and thus could be used to experimentally search for the bottom-charm baryons. The topological diagrams and the SU(3) symmetry of bottom-charm baryon decays are discussed. [ABSTRACT FROM AUTHOR]

The exotic states X 0 , 1 (2900) with the quark flavor of c s u ¯ d ¯ are recently observed in the mass spectrum of D + K - in B - → D - D + K - by the LHCb collaboration. To explore the nature of X 0 , 1 (2900) , except for analyzing their masses and decay widths as usually did in literatures, the study of their production mechanism in B-meson weak decays would provide another important information. The amplitude of B - → D - X 0 , 1 is non-factorizable. We consider the final-state-interaction effects and calculate them via the rescattering mechanism. The measured branching fractions of B - → D - X 0 , 1 are revealed. It is manifested by B - → Λ c - Ξ c (′) 0 and Λ b 0 → P c + K - that the rescattering mechanism can result in the relatively large branching fractions. The similar processes of B - → π - X 0 , 1 are also analyzed. The isospins of X 0 , 1 can be investigated by B → D X 0 , 1 ± , 0 decays. [ABSTRACT FROM AUTHOR]