相关论文: pi(-)p atom in ChPT: strong energy-level shift

We report on our determination of the values of the one and two loop low energy constants appearing in the Chiral Perturbation Theory calculation of the pi-pi scattering amplitude. For this we use a precise sum rule determination of…

Using effective field theory for a proton and antiproton bound in a Coulomb potential, the shift of the ground state energy level is calculated to arbitrary order in the scattering length. Including the next order contact interaction, the…

We calculate the $T$-matrices of elastic pion-nucleon ($\pi N$) scattering up to fourth order in SU(3) heavy baryon chiral perturbation theory. The pertinent low-energy constants are determined by fitting to $\pi N$ phase shifts below 200…

The model-independent analysis of the S- and P-wave pi-pi phase shifts was carried out. This analysis was based on the using of the Roy equations only and all available experimental data from the threshold up to dipion mass 1GeV. The S-wave…

We calculate the phase shifts in the pion-nucleon scattering using the heavy baryon formalism. We consider phase shifts for the pion energy range of 140 to $200 $ MeV. We employ two different methods for calculating the phase shifts - the…

Strong isospin-breaking (IB) contributions to both the octet and 27-plet weak K-->2 pi transitions are evaluated at next-to-leading order (NLO) in the chiral expansion. NLO contributions are shown to significantly reduce the leading order…

We calculate the S-wave decay widths and energy shifts for pi pi and pi K atoms in the framework of QCD+QED. The evaluation - valid at next-to-leading order in isospin symmetry breaking - is performed within a non-relativistic effective…

We present technical details of the evaluation of the elastic pi-pi scattering amplitude to two loops in chiral perturbation theory. In particular, we elaborate on the renormalization procedure at the two-loop order and on the evaluation of…

Compared in this work are a few sets of results, obtained from the pion-nucleon ($\pi N$) data at low energy (pion laboratory kinetic energy up to $100$ MeV) on the basis of the modelling of the $s$- and $p$-wave $K$-matrix elements (or of…

We describe the spectra and decays of pi pi and pi K atoms within a non-relativistic effective field theory. The evaluations of the energy shifts and widths are performed at next-to-leading order in isospin symmetry breaking. We provide…

We calculate the electromagnetic corrections to the isospin invariant mixing angle and to the two eigenphases for the $s$-, $p_{1/2}$- and $p_{3/2}$-partial waves for $\pi^- p$ elastic and charge exchange scattering. These corrections have…

The CP conserving amplitudes for the decays $K\to3\pi$ are calculated in Chiral Perturbation Theory. The calculation is made at the next-to-leading order including strong and local electromagnetic isospin breaking. A comparison is made…

We calculate shifts and width of 1s and 2p states of pions bound to heavy nuclei, using an optical potential with its s-wave interaction part based on chiral symmetry. This potential is constructed systematically in two-loop approximation…

pi-N and pi-pi interactions near threshold are uniquely sensitive to the chiral symmetry breaking part of the strong interaction. The pi-N sigma-term value with its implications for nucleon quark structure and the recent controversy…

Isospin breaking in the Kl4 form factors induced by the difference between charged and neutral pion masses is studied. Starting from suitably subtracted dispersion representations, the form factors are constructed in an iterative way up to…

Third order chiral perturbation theory accounts for the $\pi-N$ scattering phase shift data out to energies slightly below the position of the $\Delta$ resonance. The low energy constants are not accurately determined. Explicit inclusion of…

We calculate in chiral perturbation theory the dominant next-to-leading order correction to the $\pi\gamma$-exchange NN-potential proportional to the large isovector magnetic moment $\kappa_v = 4.7$ of the nucleon. The corresponding…

We calculate isospin breaking in pion-nucleon scattering in the threshold region in the framework of covariant baryon chiral perturbation theory. All effects due to quark mass differences as well as real and virtual photons are consistently…

The scalar-isoscalar pi-pi phase shifts are calculated in the pi-pi energy range from 600 MeV to 1600 MeV. We use results of the CERN-Cracow-Munich collaboration for the reaction pi^- p --> pi^+ pi^- n on a transversely polarized target at…

The measurement of the pion-nucleon scattering lengths constitutes a high-precision test of the methods of Chiral Pertubation Theory, which is the low-energy approach of QCD. The pion-nucleon s-wave scattering lengths are related to the…