Eta-eta' mixing in U(3) chiral perturbation theory

We investigate eta-eta' mixing in infrared regularized U(3) chiral perturbation theory by calculating the eta and eta' masses up to one-loop order. From this analysis it becomes obvious that even at leading order eta-eta' mixing does not obey the usually assumed one-mixing angle scheme if large N_c counting rules are not employed.Comment: 22 page

Two-particle scattering on the lattice: Phase shifts, spin-orbit coupling, and mixing angles

We determine two-particle scattering phase shifts and mixing angles for quantum theories defined with lattice regularization. The method is suitable for any nonrelativistic effective theory of point particles on the lattice. In the center-of-mass frame of the two-particle system we impose a hard spherical wall at some fixed large radius. For channels without partial-wave mixing the partial-wave phase shifts are determined from the energies of the nearly-spherical standing waves. For channels with partial-wave mixing further information is extracted by decomposing the standing wave at the wall boundary into spherical harmonics, and we solve coupled-channels equations to extract the phase shifts and mixing angles. The method is illustrated and tested by computing phase shifts and mixing angles on the lattice for spin-1/2 particles with an attractive Gaussian potential containing both central and tensor force parts.Comment: 28 pages, 11 figures, journal versio

SU(3) Baryon Chiral Perturbation Theory and Long Distance Regularization

The use of SU(3) chiral perturbation theory in the analysis of low energy meson-baryon interactions is discussed. It is emphasized that short distance effects, arising from propagation of Goldstone bosons over distances smaller than a typical hadronic size, are model-dependent and can lead to a lack of convergence in the SU(3) chiral expansion if they are included in loop diagrams. In this paper we demonstrate how to remove such effects in a chirally consistent fashion by use of a cutoff and demonstrate that such removal ameliorates problems which have arisen in previous calculations due to large loop effects

Inception Report beyond2020 - Approaches for a Harmonisation of RES(-E) Support in Europe: Beyond 2020. Design and impact of a harmonised policy for renewable electricity in Europe. D7.1 Report

This report concludes the inception phase of the beyond2020 project, summarising the work done up to the mid-term of the project and offering a brief outlook on forthcoming working steps