Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userExclusive Nonleptonic Decays of Heavy Baryons in a Relativistic Quark Model
64
0
0.0
(
0
)
Authors
V.E.Lyubovitskij
Ask ChatGPT about the research
No Arabic abstract
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.
rate research
Read More
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.
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.
We present a general study on exclusive semileptonic decays of heavy (B, D, B_s) to light (pi, rho, K, K^*) mesons in the framework of effective field theory of heavy quark. Transition matrix elements of these decays can be systematically characterized by a set of wave functions which are independent of the heavy quark mass except for the implicit scale dependence. Form factors for all these decays are calculated consistently within the effective theory framework using the light cone sum rule method at the leading order of 1/m_Q expansion. The branching ratios of these decays are evaluated, and the heavy and light flavor symmetry breaking effects are investigated. We also give comparison of our results and the predictions from other approaches, among which are the relations proposed recently in the framework of large energy effective theory.
We report results from a study of heavy-baryon spectroscopy within a relativistic constituent- quark model, whose hyperfine interaction is based on Goldstone-boson-exchange dynamics. While for light-flavor constituent quarks it is now commonly accepted that the effective quark-quark interaction is (predominantly) furnished by Goldstone-boson exchange - due to spontaneous chiral-symmetry breaking of quantum chromodynamics at low energies - there is currently still much speculation about the light-heavy and heavy-heavy quark-quark interactions. With the increasing amount of experimental data on heavy-baryon spectroscopy these issues might soon be settled. Here, we show, how the relativistic constituent-quark model with Goldstone-boson-exchange hyperfine interactions can be extended to charm and bottom baryons. It is found that the same model that has previously been successful in reproducing the light and strange baryon spectra is also in line with the existing phenomenological data on heavy-baryon spectroscopy. An analogous model with one-gluon-exchange hyperfine interactions for light-heavy flavors does not achieve a similarly good performance.
Exclusive semileptonic decays of bottom and charm baryons are considered within a relativistic three-quark model with a Gaussian shape for the baryon-three-quark vertex and standard quark propagators. We calculate the baryonic Isgur-Wise functions, decay rates and asymmetry parameters.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
