Threshold pion photoproduction of nucleons in the chiral quark model

Abstract

In this paper, we show that the low energy theorem (LET) of the threshold pion-photoproduction can be fully recovered in the quark model. An essential result of this investigation is that the quark-pion operators are obtained from the effective chiral Lagrangian, and the low energy theorem does not require the constraints on the internal structures of the nucleon. The pseudoscalar quark-pion coupling generates an additional term at order µ = m π /M only in the isospin amplitude A (−) . The role of the transitions between the nucleon and the resonance P 33 (1232) and P-wave baryons are also discussed, we find that the leading contributions to the isospin amplitudes at O(µ 2 ) are from the transition between the P-wave baryons and the nucleon and the charge radius of the nucleon. The leading contribution from the Pwave baryons only affects the neutral pion production, and improve the agreement with data significantly. The transition between the resonance P 33 (1232) and the nucleon only gives an order µ 3 corrections to A (−) .

Neutral pion photoproduction on the nucleon in a chiral quark model

“…Since the quark-meson coupling is invariant under the chiral transformation, some of the low-energy properties of QCD are retained. The chiral quark model has been well developed and widely applied to meson photoproduction reactions [38,[43][44][45][46][47][48][49][50][51][52][53][54]. Recently, this model has been successfully extended to πN and KN reactions as well [55][56][57][58].…”

Possible interpretation of the newly observed Ω(2012) state

“…The light pseudoscalar mesons, i.e., π, K, and η, are treated as Goldstone bosons. Since the quark-meson coupling is invariant under the chiral transformation, some of the low-energy properties of QCD are retained [24,[37][38][39]. Within the chiral quark model, the OZI allowed two-body strong decays of Ω baryons up to N ¼ 2 shell are analyzed in present work.…”

Strong decays of the newly observedD(2550),D(2600),DZhong1 2010Phys. Rev. D664761View full textAdd to dashboardCite

“…IV. In the chiral quark model [10], the low energy quarkpseudoscalar-meson interactions in the SU(3) flavor basis are described by the effective Lagrangian [11][12][13] …”

“…Considering light meson emission in a heavy-light meson strong decays, the effective quark-pseudoscalar-meson coupling operator in the center-of-mass system of the initial meson is [6,7,[11][12][13] …”