Non-perturbative chiral approach to Kp --gamma Y reactions(8)

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

CB′,MB=XB′,MB(D+F)+ZB′,MB(D F)(17)

with[12]D+

F

=

g

A=1.257andD F=0.33.ThevaluesofX’sandZ’sneededforourcalculationscanbeeasilyevaluatedusingthechirallagrangiansofRef.[12,14]andwillbegivenlater.Thephoton-baryon-baryonverticesarede nedby

µ µFγBB′=eBδBB′ κBB′

s, 0)

TγY,K p(q,k′)=QγY,K p(q,k′)+[QGT]γY,K p(q,k′)+ γY,K p(q,k′).(19)Thesecondtermoftheaboveequationhasafamiliarformfordescribingtheinitialstateinteractions

[QGT]γY,K p(q,k)=′

MB {[ d kEB(k)1

s)},

√(20)