Chiral Quark Model with Configuration Mixing

The implications of one gluon exchange generated configuration mixing in the Chiral Quark Model (χQMgcm) with SU(3) and axial U(1) symmetry breakings are discussed in the context of proton flavor and spin structure as well as the hyperon β-decay parameters. We find that χQMgcm with SU(3) symmetry breaking is able to give a satisfactory unified fit for spin and quark distribution functions, with the symmetry breaking parameters α = .4, β = .7 and the mixing angle φ = 20, both for NMC and the most recent E866 data. In particular, the agreement with data, in the case of GA/GV , ∆8, F, D, fs and f3/f8, is quite striking. It is well known that the chiral quark model (χQM) [1, 2, 3] with SU(3) symmetry is not only able to give a fair explanation of “proton spin crisis” [4] but is also able to account for the ū − d̄ asymmetry [5, 6, 7] as well as the existence of significant strange quark content s̄ in the nucleon when the asymmetric octet singlet couplings are taken into account [8]. Further, χQM with SU(3) symmetry is also able to provide fairly satisfactory explanation for various quark flavor contributions to the proton spin [9], baryon magnetic moments [3, 9] as well as the absence of polarizations of the antiquark sea in the nucleon [10, 11] . However, in the case of hyperon decay parameters the predictions of the χQM are not in tune with the data [12], for example, in comparison to the experimental numbers .21 and 2.17 the χQM with SU(3) symmetry predicts f3/f8 and ∆3/∆8 to be 1 3 and 5 3 respectively. It has been shown [10, 13] that when SU(3) breaking effects are taken into consideration within χQM, the predictions of the χQM regarding the above mentioned ratios have much better overlap with the data. It is well known that constituent quark model (CQM) with one gluon mediated configuration mixing gives a fairly satisfactory explanation of host of