%0 Journal Article
%T Two-nucleon scattering: merging chiral effective field theory with dispersion relations
%A A. M. Gasparyan
%A M. F. M. Lutz
%A E. Epelbaum
%J Physics
%D 2012
%I arXiv
%R 10.1140/epja/i2013-13115-7
%X We consider two-nucleon scattering close to threshold. Partial-wave amplitudes are obtained by an analytic extrapolation of subthreshold reaction amplitudes calculated in a relativistic formulation of chiral perturbation theory. The constraints set by unitarity are used in order to stabilize the extrapolation. Neutron-proton phase shifts are analyzed up to laboratory energies $T_{{\rm lab}}\simeq250$ MeV based on the next-to-next-to-next-to-leading order expression for the subthreshold amplitudes. We find a reasonably accurate description of the empirical S- and P-waves and a good convergence of our approach. These results support the assumption that the subthreshold nucleon-nucleon scattering amplitude may be computed perturbatively by means of the chiral expansion. The intricate soft scales that govern the low-energy nucleon-nucleon scattering are generated dynamically via a controlled analytic continuation.
%U http://arxiv.org/abs/1212.3057v2