Photoproduction of Theta^+(1540,1/2^+) reexamined with new theoretical information

TL;DR

This paper reexamines the photoproduction of the exotic Theta^+(1540) baryon using an effective Lagrangian approach, incorporating new theoretical coupling data and hadronic form factors, highlighting the importance of K*-exchange in photon beam asymmetries.

Contribution

It introduces updated coupling strengths from the chiral quark-soliton model and considers crossing-symmetric form factors in the analysis of Theta^+ photoproduction.

Findings

K*-exchange significantly influences photon beam asymmetries.

New coupling data from chiQSM alters the understanding of production mechanisms.

Hadronic form factors satisfy on-shell conditions, improving model consistency.

Abstract

We reinvestigate the photoproduction of the exotic pentaquark baryon Theta^+(1540,1/2^+) from the gamma N -> Kbar Theta^+ reaction process within the effective Lagrangian approach, taking into account new theoretical information on the K-N-Theta and K*-N-Theta coupling strengths from the chiral quark-soliton model (chiQSM). We also consider the crossing-symmetric hadronic form factor, satisfying the on-shell condition as well. Due to the sizable vector and tensor couplings for the vector kaon, g_{K* N Theta} and f_{K* N Theta}, which are almost the same with the vector coupling g_{K N Theta} ~ 0.8 for the pseudoscalar kaon, the K*-exchange contribution plays a critical role in the photon beam asymmetries.