Radiative pion photoproduction in covariant chiral perturbation theory

Neutral pion photoproduction on nuclei in baryon chiral perturbation theory.

Pion–Pion and Pion–Nucleon Interactions in Chiral Perturbation Theory*

Elastic pion–pion and pion–nucleon scattering are reviewed in the context of chiral perturbation theory. Theoretical results from systematic low–energy expansions to O(p) for ππ and to O(p) for πN are compared with experimental data. Possible future developments are outlined. Talk given at the Workshop on Chiral Dynamics 1997 Mainz, Germany, Sept. 1 5, 1997 To appear in the Proceedings * Work s...

Pion Scattering in Wilson Chiral Perturbation Theory

We compute the scattering amplitude in Wilson Chiral Perturbation Theory for two flavors. The lattice spacing effects due to the explicit chiral symmetry breaking are kept through O(a2), and we consider the regime where the quark mass m is of order aΛQCD. Analytic expressions for the scattering lengths in different isospin channels are given. As a result of the O(a2) terms the scattering length...

Pion-nucleon scattering in covariant baryon chiral perturbation theory with explicit Delta resonances

De-Liang Yao, ∗ D. Siemens, † V. Bernard, ‡ E. Epelbaum, § A. M. Gasparyan, 4, ¶ J. Gegelia, 5, ∗∗ H. Krebs, †† and Ulf-G. Meißner 1, ‡‡ Institute for Advanced Simulation, Institut für Kernphysik and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich, Germany Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44780 Bochum, Germany Groupe de Physique Théoriqu...

Positivity Constraints on Chiral Perturbation Theory Pion-Pion Scattering Amplitudes

We test the positivity property of the chiral perturbation theory (ChPT) pion-pion scattering amplitudes within the Mandelstam triangle. In the one-loop approximation, O(p4), the positivity constrains only the coefficients b3 and b4, namely one obtains that b4 and the linear combination b3 + 3b4 are positive quantities. The two-loops approximation gives inequalities involving all the six arbitr...