Revisiting Lambda _{b}rightarrow Lambda _{c} and Sigma _{b}rightarrow Sigma _{c} weak decays in the light-front quark model

Hong-Wei Ke,Ning Hao,Xue-Qian Li

doi:10.1140/epjc/s10052-019-7048-1

Hong-Wei Ke, Ning Hao + Show 1 more

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https://doi.org/10.1140/epjc/s10052-019-7048-1

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Abstract

In this work, we study Lambda _{b}rightarrow Lambda _{c} and Sigma _{b}rightarrow Sigma _{c} weak decays in the light-front quark model. As is well known, the key point for such calculations is properly evaluating the hadronic transition matrix elements which are dominated by the non-perturbative QCD effect. In our calculation, we employ the light-front quark model and rather than the traditional diquark picture, we account the two spectator light quarks as individual ones. Namely during the transition, they retain their color indices, momenta and spin polarizations unchanged. Definitely, the subsystem composed of the two light quarks is still in a color-anti-triplet and possesses a definite spin, but we do not priori assume the two light quarks to be in a bound system–diquark. Our purpose is probing the diquark picture, via comparing the results with the available data, we test the validity and applicability of the diquark structure which turns a three-body problem into a two-body one, so greatly simplifies the calculation. It is indicated that the two approaches (diquark and a subsystem within which the two light quarks are free) lead to similar numerical results even though the model parameters in the two schemes might deviate slightly. Thus, the diquark approach seems sufficiently reasonable.

Highlights

B is the ground state of b baryons so it can only decay via weak interactions
Besides study on the baryon structure, its weak decays may be valuable for determining the CKM parameter Vcb as a compensation to the measurements on mesons and one can investigate the non-perturbative QCD effects in the heavy baryon system because of the existence of the heavy quark. b is heavier than b which would dominantly decay via the portal b+π, a sizable branching ratio of its weak decays may imply a possible involvement of new physics, so can serve as an ideal laboratory for searching new physics beyond the standard model
[4] Ebert et al used their relativistic quark model to calculate the decay rates of several weak decay modes where baryons consist of a heavy quark and a light diquark; Singleton examined the semileptonic decays of spin

Summary

Introduction

B is the ground state of b baryons so it can only decay via weak interactions. besides study on the baryon structure, its weak decays may be valuable for determining the CKM parameter Vcb as a compensation to the measurements on mesons and one can investigate the non-perturbative QCD effects in the heavy baryon system because of the existence of the heavy quark. b is heavier than b which would dominantly decay via the portal b+π , a sizable branching ratio of its weak decays may imply a possible involvement of new physics, so can serve as an ideal laboratory for searching new physics beyond the standard model. Employed their relativistic three-quark model to study the weak decays of several baryons under the heavy quark limit; lately, Ivanov et al [7] studied heavy baryon decays in the Bethe–Salpeter approach under the heavy quark limit. By those works the properties of the weak decays of b and b have been investigated and the non-perturbative QCD effects for baryons (at least for heavy baryons) are partly understood or at least can be approximately handled.

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