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Register a new userNonleptonic two-body decays of single heavy baryons $Lambda_Q$, $Xi_Q$, and $Omega_Q$ $(Q=b,c)$ induced by $W$ emission in the covariant confined quark model
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We have made a survey of heavy-to-heavy and heavy-to-light nonleptonic heavy baryon two-body decays and have identified those decays that proceed solely via $W$-boson emission, i.e. via the tree graph contribution. Some sample decays are $Omega_{b}^{-}toOmega_{c}^{(*)0}rho^{-}(pi^{-}),, Omega_{b}^{-}toOmega^{-}J/psi(eta_{c}),, Xi_{b}^{0,-}toXi^{0,-}J/psi(eta_{c}),, Lambda_{b}to Lambda J/psi(eta_{c}),, Lambda_{b}to Lambda_{c} D_{s}^{(ast)},, Omega_{c}^{0}toOmega^{-}rho^{+}(pi^{+})$, and $Lambda_c to p phi$. We make use of the covariant confined quark model previously developed by us to calculate the tree graph contributions to these decays. We calculate rates, branching fractions and, for some of these decays, decay asymmetry parameters. We compare our results to experimental findings and the results of other theoretical approaches when they are available. Our main focus is on decays to final states with a lepton pair because of their clean experimental signature. For these decays we discuss two-fold polar angle decay distributions such as in the cascade decay $Omega_{b}^{-}toOmega^{-}(to Xipi,Lambda K^{-})+J/psi(to ell^{+}ell^{-})$. Lepton mass effects are always included in our analysis.
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Exclusive nonleptonic decays of bottom and charm baryons are studied within a relativistic quark model. We include factorizing as well as nonfactorizing contributions to the decay amplitudes.
In this article, we study the rare decays corresponding to $b to d$ transition in the framework of covariant confined quark model. The transition form factors for the channels $B^{+(0)} to (pi^{+(0)}, rho^{+(0)},omega)$ and $B_s^0 to K^{(*)0}$ are computed in the entire dynamical range of momentum transfer squared. Using the form factors, we compute the branching fractions of the rare decays and our results are found to be matching well with the experimental data. We also compute the ratios of the branching fractions of the $b to s$ to $b to d$ rare decays using the inputs from previous papers on this model. Further, using the form factors, model dependent and independent parameters, we also compute different other physical observables such as forward backward asymmetry, longitudinal polarization and angular observables in the entire $q^2$ range as well as in $q^2$ bins [0.1 -- 0.98] GeV$^2$ and [1.1 -- 6] GeV$^2$. We also compare our findings with different theoretical predictions.
The recent discovery of double charm baryon states by the LHCb Collaborarion and their high precision mass determination calls for a comprehensive analysis of the nonleptonic decays of double and single heavy baryons. Nonleptonic baryon decays play an important role in particle phenomenology since they allow to study the interplay of long and short distance dynamics of the Standard Model (SM). Further, they allow one to search for New Physics effects beyond the SM. We review recent progress in experimental and theoretical studies of the nonleptonic decays of heavy baryons with a focus on double charm baryon states and their decays. In particular, we discuss new ideas proposed by the present authors to calculate the $W$-exchange matrix elements of the nonleptonic decays of double heavy baryons. An important ingredient in our approach is the compositeness condition of Salam and Weinberg, and an effective implementation of infrared confinement both of which allow one to describe the nonperturbative structure of baryons composed of light and heavy quarks. Further we discuss an ab initio calculational method for the treatment of the so-called $W$-exchange diagrams generated by $W^{pm}$ boson exchange between quarks. We found that the $W^{pm}$-exchange contributions are not suppressed in comparison with the tree-level (factrorizing) diagrams and must be taken into account in the evaluation of matrix elements. Moreover, there are decay processes such as the doubly Cabibbo-suppressed decay $Xi_c^+ to p phi$ recently observed by the LHCb Collaboration which is contributed to only by one single $W$-exchange diagram.
Bethe-Salpeter approach has been applied to the study of b --> c transitions both for heavy mesons and heavy baryons. Meson and baryon IW functions are calculated on the equal footing. A reasonable agreement with the experimental data for heavy to heavy semileptonic transitions has been obtained.
We analyze charm meson semileptonic $D to V l u_l$ and $Dto P l u_l$ and nonleptonic $D to P V$, $D to PP$ and $D to VV$ decays within a model which combines the heavy quark effective Lagrangian and chiral perturbation theory.
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