Related papers: Pionic Hydrogen at PSI
We enforce chiral Ward identities on the vertices of the linear sigma model to take into account the width of the scalar sigma, considered as a true physical resonance. We consider pion scattering at very low energies and, from a fit to the…
The hadronic shift in pionic hydrogen has been redetermined to be $\epsilon_{1s}=7.086\,\pm\,0.007(stat)\,\pm\,0.006(sys)$\,eV by X-ray spectroscopy of ground state transitions applying various energy calibration schemes. The experiment was…
We obtain reliable $\pi\pi$ scattering amplitudes consistent with experimental data, both at low and high energies, and fulfilling appropriate analyticity properties. We do this by first fitting experimental low energy ($s^{1/2}\leq1.42…
We calculate the pion-pion elastic scattering phase shifts for pion masses from the chiral limit to values of interest for lattice studies. At low energies, we use the standard Chiral Perturbation Theory expressions to one and two loops. In…
The S-wave scattering length of the strong pion-deuteron (pi D) scattering is calculated in the relativistic field theory model of the deuteron suggested in [1,2].The theoretical result agrees well with the experimental data. The important…
We develop a generalized version of heavy-baryon chiral perturbation theory to describe pion-nucleon scattering in a kinematic domain that extends continuously from threshold to the delta-isobar peak. The $P$-wave phase shifts are used to…
We discuss the possibility to extract the neutron-neutron scattering length a_{nn} from experimental spectra on the reaction gamma d --> pi^+ nn. The transition operator is calculated to high accuracy from chiral perturbation theory. We…
An effective field theory treatment of nucleon-nucleon scattering at low energy shows much promise and could prove a useful tool in the study of nuclear matter at both ordinary and extreme densities. The analysis is complicated by the…
The longest-range part of the nuclear force due to the one-pion exchange governs the energy dependence of the scattering amplitude in the near-threshold region and imposes correlations between the coefficients in the effective range…
The understanding of few-nucleon systems at low energies is essential, e.g. for accurate predictions of element abundances in big-bang and stellar fusion. Novel effective field theories, taking only nucleons, or nucleons and pions as…
We compute pion-nucleon scattering at tree-level within a gauged linear sigma model which contains the nucleon and its chiral partner. Such an investigation in principle allows to make definite predictions as to whether the main…
We present a novel analysis of the $\pi N$ scattering amplitude in Lorentz covariant baryon chiral perturbation theory renormalized in the extended-on-mass-shell scheme. This amplitude, valid up to $\mathcal{O}(p^3)$ in the chiral…
Pion-nucleus elastic scattering at energies above the Delta(1232) resonance is studied using both pi+ and pi- beams on 12C, 40Ca, 90Zr, and 208Pb. The present data provide an opportunity to study the interaction of pions with nuclei at…
We propose a non relativistic effective Lagrangian approach to study hadronic atom observables in the framework of QCD (including photons). We apply our formalism to derive a general expression for the width of the pi+pi- atom decaying into…
We present a convergent variational basis-set calculational scheme for elastic scattering of positronium atom by hydrogen atom in S wave. Highly correlated trial functions with appropriate symmetry are needed for achieving convergence. We…
High statistics sample of kaon decays collected by NA48-CERN experiment allowed two independent measurements of the pion scattering length. Methods and Results are discussed
The isospin-2 pi pi system provides a useful testing ground for determining elastic hadron scattering parameters from finite-volume spectra obtained using lattice QCD computations. A reliable determination of the excited state spectrum of…
We calculate the complete $T$-matrices of pion-nucleon ($\pi N$) scattering to the third order in heavy baryon SU(3) chiral perturbation theory. The baryon mass in the chiral limit $M_0$ and the low-energy constants are determined by…
Kaonic hydrogen is studied with various realistic potentials in an accurate numerical approach based on Sturmian functions. The kaon-proton scattering length extracted from the 1s energy shift of the kaonic hydrogen by applying the…
The relationship between the pionium lifetime and the $\pi\pi$ scattering lengths is established, including the sizable electromagnetic corrections. The bound state formalism that is used is that of constraint theory which provides a…