Threshold pion electro- and photoproduction off nucleons in covariant chiral perturbation theory

Threshold pion photoproduction of nucleons in the chiral quark model.

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 e ective chiral Lagrangian, and the low energy theorem does not require the constraints on the internal structures of the nucleon. The pseudoscalar quark-pion cou...

Neutral pion photoproduction on nuclei in baryon chiral perturbation theory.

Unitarity constraint for threshold coherent pion photoproduction on the deuteron and chiral perturbation theory

The contribution of the two-step process γd → pn → π0d to the imaginary part of the amplitude for coherent pion production on the deuteron is calculated exploiting unitarity constraints. The result shows that this absorptive process is not negligible and has to be considered in an extraction of the elementary neutron production amplitude from the γd → π0d cross section at threshold. In addition...

Threshold Pion Photo- and Electroproduction in Chiral Perturbation Theory

Threshold pion photoand electroproduction off nucleons allow us, by the use of a well-understood probe, to test our understanding of the strong interaction at low energies, i.e. in the non–perturbative regime. Over the last few years, renewed interest in these reactions has emerged. This was first triggered through precise new data on neutral pion photoproduction [1] which lead to a controversy...

The Threshold Pion-Photoproduction Of Nucleons In The Chiral Quark Model

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 co...