Non-perturbative chiral approach to Kp --gamma Y reactions(7)

A recently developed nonperturbative chiral approach to describe the S=-1 meson-baryon reactions has been extended to investigate the near threshold $K^- p \to \gamma \Lambda, \gamma \Sigma^0$ reactions. With the parameters governed by chiral SU(3) symmetr

III.THEK P→γYAMPLITUDE

WefollowhereintheS= 1sectorsimilarstepsasdonein[9,18]intheS=0sector,butstartingfromarelativisticformulationoftheproblem.TostudytheK p→γYreactionwithY=Λ,Σ0,wereturntotheBethe-SalpeterEquation(4),settingi=γYandj=K p.Totheleadingorderintheelectromagneticcouplingconstante,wehave

tγY,K p(q,k′;P)=AγY,K p(q,k′;P)

+i

×MB d4k(P k) MB+i

1

2f

2f

2f

2f]eMµ] µFγYY′11]γ5kγ5(k q) ·(2k q)(16)]eM[ γ5 ],

whereeMisthechargeofthemesonM.TheSU(3)couplingconstantsCB′,MBfortheMB B′transitionarede nedby[12]