Related papers: Experimental Evidence for Optimal Resonances in Pi…
The isoscalar and isovector scattering lengths (b_0,b_1) are determined using a unitarized coupled channel approach based on chiral Lagrangians. Using experimental values of pionic hydrogen and deuterium as well as low energy pi N…
Incoherent photoproduction of pions on the deuteron in the Delta(1232) resonance region is studied, where besides the impulse approximation complete two-body rescattering in the nucleon-nucleon and pion-nucleon final state subsystems is…
Resonances of Schr\"odinger Hamiltonians with point interactions are considered. The main object under the study is the resonance free region under the assumption that the centers, where the point interactions are located, are known and the…
Measurements of neutron total cross-sections are both extensive and extremely accurate. Although they place a strong constraint on theoretically constructed models, there are relatively few comparisons of predictions with experiment. The…
We present and apply a novel scheme for studying photon- and pion-nucleon scattering beyond the threshold region. Partial-wave amplitudes for the $\gamma\, N$ and $\pi N$ states are obtained by an analytic extrapolation of subthreshold…
The pi+ d scattering and the d(p,n) charge exchange reaction are used to study the Delta-Nucleon interaction in the Delta resonance energy region. Various observables, such as inclusive and exclusive cross sections, angular distributions,…
Motivated by a recent measurement of proton-proton elastic scattering observables up to 3.0 GeV, we investigate the description of those data within models of the nucleon-nucleon (NN) interaction valid above the pion production threshold.…
The experimental and theoretical status of elastic electron scattering from the nucleon is reviewed. A wealth of new data of unprecedented precision, especially at small values of the momentum transfer, in parallel to new theoretical…
We make a study of the (pi^- p --> K^0 pi^0 Lambda), (pi^+ p --> K^+ pi^+ Lambda), (K^+\bar{K}^0 p), (K^+ pi^+ Sigma^0), (K^+ pi^0 Sigma^+), and (eta pi^+ p) reactions, in which the basic dynamics is given by the excitation of the…
The amplitudes of the pion electroproduction from the nucleon are derived up to third order in the chiral effective theory including explicit $\Delta$(1232) >. The Q^2 evolutions of weighted integrals of amplitudes are presented.
Weak pion production off the nucleon at low energies has been systematically investigated in manifestly relativistic baryon chiral perturbation theory with explicit inclusion of the $\Delta$(1232) resonance. Most of the involved low-energy…
The unitary isobar model MAID is used for a partial wave analysis of pion photoproduction and electroproduction data on the nucleon. In particular we have taken emphasis on the region of the Delta(1232) resonance and have separated the…
In the context of chiral SU(2) perturbation theory, pion-kaon scattering is analysed near the threshold to fourth chiral order. The scattering amplitude is calculated both in the relativistic framework and by using an approach similar to…
In this paper we prove a new optimal bound on the logarithmic slope of the elastic slope when: elastic cross section and differential cross sections in forward and backward directions are known from experimental data. The results on the…
All available theoretical estimates of neutrino-induced coherent pion production rely on the 'local approximation' for the Delta propagator. The validity of this approximation is scrutinized. It is found that the local approximation…
The (\pi^{-}\Delta^{++}) production on the nucleon by real and virtual photons is discussed as initial step in a simple model approach for the two pion photo- and electroproduction on the nucleon, with emphasis on nucleon resonance…
I discuss the problem of constructing an effective low-energy theory in the vicinity of a resonance or a bound state. The focus is on the example of the $\Delta(1232)$, the lightest resonance in the nucleon sector. Recent developments of…
The electric alpha and magnetic beta pion Compton polarizabilities characterize the pion's deformation in the electromagnetic field of the gamma during gamma-pi Compton scattering. The chi_PT effective Lagrangian, using data from radiative…
Using dispersion theory with an improved description of the two-pion continuum based on the precise Roy-Steiner analysis of pion-nucleon scattering, we analyze recent data from electron-proton scattering. This allows for a high-precision…
The aim of the DIRAC experiment at CERN is to provide an accurate determination of S-wave pion-pion scattering lengths from the measurement of the lifetime of the pi+ pi- atom. The measurement will be done with precision comparable to the…