Semi-leptonic Octet Baryon Weak Axial-Vector Form Factors in the Chiral Constitutent Quark Model

The weak vector and axial-vector form factors have been investigated for the semi-leptonic octet baryon decays in the chiral constituent quark model with configuration mixing (χCQMconfig). The effects of SU(3) symmetry breaking and configuration mixing have also been investigated and the results are not only in good agreement with existing experimental data but also show improvement over other phenomenological models. The measurements of the polarized struture functions in the deep inelastic scattering (DIS) experiments indicate that the valence quarks of the proton carry only about 30% of its spin and also establishes the asymmetry of the quark distribution functions [1]. This is referred to as the “proton spin problem” and it relates the DIS measurements to the weak vector and axial-vector form factors (fi=1,2,3(Q ) and gi=1,2,3(Q )) of the semileptonic baryon decays [2]. The data to study the form factors in the early eighties was analyzed under the assumptions of exact SU(3) symmetry [3]. However, the experiments performed recently [4] are more precise and indicate that SU(3) symmetry breaking effects are important. The broader question of SU(3) symmetry breaking has been recently discussed by several authors in various phenomenological models [5] however, the results of all these models are not in agreement with each other on the magnitude as well as sign of these form factors. Pending further experiments, it is of interest to estimate the role of SU(3) symmetry breaking in the weak form factors. Chiral constituent quark model with configuration (χCQMconfig) [6, 7, 8] can yield an adequate description of the “quark sea” generation through the chiral fluctuations and has been successful in explaining various general features of the quark flavor and spin distribution functions and baryon magnetic moments. It, therefore, becomes desirable to carry out a detailed phenomenological analysis within the framework of χCQMconfig to