Vector transition form factors of the $N K^*\to\Theta^+ $ and $N \bar{K}^*\to \Sigma_{\bar{10}}^{*-}$ in the SU(3) chiral quark-soliton model

TL;DR

This paper calculates vector transition form factors for pentaquark baryons within the SU(3) chiral quark-soliton model, revealing significant effects from SU(3) symmetry breaking and aligning with experimental null results.

Contribution

It introduces a detailed calculation of transition form factors including symmetry-breaking effects and derives the generalized Ademollo-Gatto theorem in this context.

Findings

Form factors are dominated by wave-function corrections.

Estimated coupling constants are consistent with experimental null results.

SU(3) symmetry-breaking significantly impacts the form factors.

Abstract

We investigate the vector transition form factors of the nucleon and vector meson K^* to the pentaquark baryon Theta^+ within the framework of the SU(3) chiral quark-soliton model. We take into account the rotational 1/N_c and linear $m_{\rm s}$ corrections, assuming isospin symmetry and employing the symmetry-conserving quantization. It turns out that the leading-order contributions to the form factors are almost cancelled by the rotational corrections. Because of this, the flavor SU(3) symmetry-breaking terms yield sizeable effects on the vector transition form factors. In particular, the main contribution to the electric-like transition form factor comes from the wave-function corrections, which is a consequence of the generalized Ademollo-Gatto theorem derived in the present work. We estimate with the help of the vector meson dominance the K^* vector and tensor coupling constants for the Theta^+: $g_{K^{*}N\Theta}=0.74 - 0.87$ and $f_{K^{*}N\Theta}=0.53 - 1.16$. We argue that the outcome of the present work is consistent with the null results of the CLAS experiments in the reactions gamma n -> K^- Theta^+ and gamma p ->bar{K}^0 Theta^+. The results of the present work are also consistent with the recent experiments at KEK. In addition, we present the results of the $\Sigma_{\bar{10}}\to N\bar{K}^*$ transition form factors and its $\bar{K}^*N\Sigma_{\bar{10}}$ coupling constants.