Vector and axial-vector structures of the Theta^+

TL;DR

This paper calculates the vector and axial-vector transition properties of the pentaquark Theta^+ using the SU(3) chiral quark-soliton model, predicting a very narrow decay width consistent with experimental data.

Contribution

It provides the first detailed theoretical estimates of the vector and axial-vector couplings and decay width of Theta^+ within the chiral quark-soliton model.

Findings

Vector coupling constant g_{K^{*}N Theta} = 0.81

Axial-vector coupling g_{A}^* = 0.05

Decay width Gamma_{Theta -> NK} = 0.71 MeV

Abstract

We present in this talk recent results of the vector and axial-vector transitions of the nucleon to the pentaquark baryon Theta^{+}, based on the SU(3) chiral quark-soliton model. The results are summarized as follows: K^{*}-N-Theta vector and tensor coupling constants turn out to be g_{K^{*}N Theta} = 0.81 and f_{K^{*}N Theta}=0.84, respectively, and the KN Theta axial-vector coupling constant to be g_{A}^* = 0.05. As a result, the total decay width for Theta^+ to NK becomes very small: Gamma_{Theta -> NK} = 0.71 MeV, which is consistent with the DIANA result Gamma_{Theta -> NK}=0.36 +- 0.11 MeV.