Related papers: Pion axioproduction: The Delta resonance contribut…
The S-matrix approach is applied to charged and neutral pion production in pp collisions, in which the spin/isospin channels filter differently the rescattering mechanism. The chiral perturbation theory rescattering amplitude is employed.…
Motivated by the renewed interest in studying the pion production on nuclei with protons at few GeV incident energies, we investigate the pion production in proton-proton collisions over an energy range of 300 $MeV$ to 2 $GeV$. Starting…
Near threshold neutral pion electroproduction on the deuteron is studied in the framework of heavy baryon chiral perturbation theory. We include the next-to-leading order corrections to the three-body contributions. We find an improved…
The experimental data on pi N scattering in the elastic energy region T_pi < 250 MeV are analyzed within the multichannel K-matrix approach with effective Lagrangians. Isospin invariance is not assumed in this analysis and the physical…
Based on the recent phenomenological analysis done by M. Mojzis, Eur. Phys. Jour. {\bf C2} (1998) 182, of $\pi N $ scattering within the framework of Heavy Baryon Chiral Perturbation Theory we predict, after a suitable unitarization of the…
We develop the formalism for coherent two pion photoproduction in nuclei and perform actual calculations of cross sections for $\pi^-\pi^+$ and $\pi^0\pi^0$ photoproduction on $^{12}C$. We find that due to the isospin symmetry the cross…
In this present investigation, we explore the elastic scattering of pions with nuclei ($\pi$-$A$), primarily influenced by the $\Delta$(1232) resonance, within the Eikonal-Glauber model. The medium effects are incorporated by considering…
The extension of the concept of generalized parton distributions leads to the introduction of baryon to meson transition distribution amplitudes (TDAs), non-diagonal matrix elements of the nonlocal three quark operator between a nucleon and…
The deuteron spectrum in n+p -> 2 H(pi pi) at k_n = 1.88 GeV/c and theta_d = 0^o is explained by considering a Delta Delta excitation as the dominant reaction mechanism for the 2 pi production. We present a new theoretical approach based on…
Based on a counting scheme for the application of chiral perturbation theory to pion production in NN collisions p-wave production is studied. It is demonstrated that, contrary to the s-wave production where loops enter at too low an order…
Threshold neutral pion photoproduction on the deuteron is studied in the framework of baryon chiral perturbation theory beyond next-to--leading order in the chiral expansion. To fourth order in small momenta, the amplitude is finite and a…
We study the production amplitude for the reaction $NN\to NN\pi$ up to next-to-leading order in chiral perturbation theory. We show that the irreducible chiral loops at this order exactly cancel those terms that arise from the off-shell…
We present a method to calculate pion electro-production amplitudes in a coupled-channel framework incorporating quasi-bound quark-model states. The method offers a clear prescription how to extract the resonant part of the amplitudes, even…
In this work, we present an updated model for nuclear $\pi^0$ photoproduction, which incorporates pion second-order rescattering on intermediate excited nuclear states. Our approach is based on the distorted wave impulse approximation in…
Photo- and electroproduction of pions and eta-mesons is studied on the nucleon. The formalism of such reactions is presented including polarization degrees of freedom and theoretical approaches are discussed. In particular, the threshold…
Photo disintegration of the deuteron and photo pionproduction on the deuteron are described in the region of the $\Delta$-resonance. The two reactions are unitarily coupled. A novel definition of electromagnetic exchange currents in the…
The dynamical model of pion electroproduction has been extended to investigate the weak pion production reactions. The predicted cross sections of neutrino-induced pion production reactions are in good agreement with the existing data. We…
We consider multi-particle contributions to nucleon two- and three-point functions from the perspective of chiral dynamics. Lattice nucleon interpolating operators, which have definite chiral transformation properties, can be mapped into…
We evaluate, within one-loop chiral perturbation theory, the two-pion exchange diagrams with single and double delta-isobar excitation contributing to elastic NN-scattering. We find that virtual $\Delta$-excitation processes (in the static…
The pion production by sigma decay and its relation with chiral symmetry restoration in a hot and dense matter are investigated in the framework of the Nambu-Jona-Lasinio model. The decay rate for the process sigma -> 2pion to the lowest…