Magnetic and Axial-Vector Transitions of the Baryon Antidecuplet

Abstract

We report the recent results of the magnetic transitions and axial-vector transitions of the baryon antidecuplet within the framework of the chiral quark-soliton model. The dynamical model parameters are fixed by experimental data for the magnetic moments of the baryon octet, for the hyperon semileptonic decay constants, and for the singlet axialvector constant. The transition magnetic moments μΛΣ and μN∆ are well reproduced and other octet-decuplet and octet-antidecuplet transitions are predicted. In particular, the present calculation of μΣΣ∗ is found to be below the upper bound 0.82μN that the SELEX collaboration measured very recently. The results explains consistently the recent findings of a new N∗ resonance from the GRAAL and Tohoku LNS group. We also obtain the transition axial-vector constants for the Θ → KN from which the decay width of the Θ pentaquark baryon is determined as a function of the pion-nucleon sigma term ΣπN . We investigate the dependence of the decay width of the Θ on the g (0) A , with the g (0) A varied within the range of the experimental uncertainty. We show that a small decay width of the Θ → KN , i.e. ΓΘKN ≤ 1 MeV, is compatible with the values of all known semileptonic decays with the generally accepted value of g (0) A ≈ 0.3 for the proton.