β decay of hyperons in a relativistic quark model

Abstract

A relativistic constituent quark model is used to calculate the semileptonic beta decay of nucleons and hyperons. The parameters of the model, namely, the constituent quark mass and the confinement scale, are fixed by a previous calculation of the magnetic moments of the baryon octet within the same model. We discuss the momentum dependence of the form factors, possible configuration mixing and SU(3) symmetry breaking. We conclude that the relativistic constituent quark model is a good framework to analyze electroweak properties of the baryons.

SU(3)-breaking corrections to the hyperon vector coupling f1(0) in covariant baryon chiral perturbation theory

“…Second, for three of the four transitions, the δ (3) corrections have a different sign than the δ (2) ones. In Table V, we compare our results with those obtained from other approaches, including large N c fits [3], quark models [11,12,13], and two quenched LQCD calculations [19,20]. The large N c results in general favor positive corrections, which are consistent with our central values.…”

“…Theoretical estimates of SU(3)-breaking corrections to f 1 (0) have been performed in various frameworks, including quark models [11,12,13], large-N c fits [3], and chiral perturbation theory (ChPT) [14,15,16,17,18]. These SU(3)-breaking corrections have also been studied recently in quenched lattice QCD (LQCD) calculations for two of the four independent channels (assuming isospin symmetry): Σ − → n [19] and Ξ 0 → Σ + [20].…”

Semileptonic Hyperon Decays and Cabibbo-Kobayashi-Maskawa Unitarity

“…The quark-model computations find that the f 1 form factors for the different ∆S = 1 decays are reduced by a factor, the same for all decays, given as 0.987 in [17], and 0.975 in [18], a decrease respectively of 1.3% or 2.5%. This is a very reasonable result, the decrease arising from the mismatch of the wave functions of baryons containing different numbers of the heavier s quarks.…”

“…We will limit our discussion to the effects that are most relevant for the determination of V us . Turning our attention first to SU (3)-breaking corrections to the f 1 form factor, we find in the literature computations that use some version of the quark model, as in [17,18], or some version of chiral perturbation theory, as in [15,19,20].…”

Measurement of the branching ratio of the decay Ξ0→Σ+μ−νBatley1, Kalmus2, Lazzeroni3 et al. 2013Physics Letters B5030View full textAdd to dashboardCite

“…In this framework, measurements on Ξ 0 semileptonic decays and on the related parameters are fundamental to further increase our knowledge on the constituents of the baryon octet. In particular, a clear evidence for the decay Ξ 0 → Σ + µ − ν µ and a measurement of its branching ratio will add one more constraint to the theoretical frameworks [2,3,4,5,6] built to explain the behaviour of the baryon semileptonic decays.…”