Related papers: The piNN vertex function in a meson-theoretical mo…
The in-medium pion properties, {\it i.e.} the temporal pion decay constant $f_t$, the pion mass $m_\pi^*$ and the wave function renormalization, in symmetric nuclear matter are calculated in an in-medium chiral perturbation theory up to the…
Considering analyticity, unitarity and an influence of coupled channels, experimental data on the isovector P-wave of pion-pion scattering was analyzed to study rho-like mesons below 1900 MeV. The analysis indicates evidently that in the…
The meta distribution of the signal-to-interference-ratio (SIR) is an important performance indicator for wireless networks because, for ergodic point processes, it describes the fraction of scheduled links that achieve certain reliability,…
We determine the $\pi NN$ and $\pi N\Delta$ formfactors from the $P_{11}$ resp. $P_{33}$ partial wave of $\pi N$ scattering by dressing corresponding bare vertices with the help of $\pi N$ non--pole contributions. The underlying model is…
We use a configuration space chiral model in order to evaluate nucleon and delta sigma-terms. Analytic expressions are consistent with chiral counting rules and give rise to expected non-analytic terms in the chiral limit. We obtain the…
In the approach, based on analyticity and unitarity and assuming an influence of coupled channels, experimental data on the isovector P-wave of pion-pion scattering have been analyzed to study rho-like mesons below 1.9 GeV.
We directly calculate spectral functions in the O(N)-model at finite temperature within the framework of the Functional Renormalization group. Special emphasis is put on a fully numerical framework involving four-dimensional regulators…
We present a nucleon resonance analysis by simultaneously considering all pion- and photon-induced experimental data on the final states gamma N, pi N, 2 pi N, eta N, K Lambda, K Sigma, and omega N for energies from the nucleon mass up to…
{\bf{Purpose}:} In this paper, the proton resonance width of the near-threshold resonance is calculated using two different approaches. The values of the proton width are used to calculate the low-energy $S$-factor. \\ {\bf{Method:}} First,…
A dependence of the value of the pion-nucleon sigma term on higher partial waves is discussed. Two recent predictions of a high value of sigma term are scrutinezed. It has been concluded that the main reason for obtaining high values of the…
The pion structure function is investigated in a simple model, where the pion and its constituent quark fields are coupled through the simplest pseudoscalar coupling. The imaginary part of the forward gamma* pi -> gamma* pi scattering…
The relativistic amplitudes of pion photoproduction are evaluated by dispersion relations at t=const. The imaginary parts of the amplitudes are taken from the MAID model covering the absorption spectrum up to center-of-mass energies W = 2.2…
Starting from the Hubbard model in the weak-coupling limit, we derive a spin-fermion model where the collective spin excitations are described by a non-linear sigma model. This result is used to compute the fermion spectral function $A({\bf…
Pion pion scattering is studied in a generalized linear sigma model which contains two scalar nonets (one of quark-antiquark type and the other of diquark-antidiquark type) and two corresponding pseudoscalar nonets. An interesting feature…
We compute the density dependence of in-medium pion properties, such as mass, wave function renormalization, and decay constant in the correlation function approach, and how they change under the influence of isospin-asymmetric nuclear…
The energies and widths of $DNN$ quasi-bound states with isospin I=1/2 are evaluated in two methods, the fixed center approximation to the Faddeev equation and the variational method approach to the effective one-channel Hamiltonian. The…
We present a new, model-independent method to analyze radiative decays of mesons to a vector, isovector pair of pions of invariant mass square below the first significant pion-pion threshold in the vector channel. It is based on a…
Parity violating asymmetry in inclusive scattering of longitudinally polarized electrons by unpolarized protons with $\pi^0$ or $\pi^+$ meson production, is calculated as a function of the momentum transfer squared $Q^2$ and the total…
The Sigma beam asymmetry for positive pion photoproduction on the proton has been measured over an angular range of 40-170 deg at photon energies from 0.8 to 1.5 GeV. The resulting data set includes 237 accurate points, 136 of these…
A model for low-energy meson-baryon interaction in the strange sector is presented. The interaction is described in terms of separable potentials with multiple partial waves considered. A general solution of Lippmann-Schwinger equation for…