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arXiv · 1212.3057

Two-nucleon scattering: merging chiral effective field theory with dispersion relations

A. M. Gasparyan·M. F. M. Lutz·E. Epelbaum
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Abstract

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.

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A. M. Gasparyan, M. F. M. Lutz, E. Epelbaum. 2012-12-13. Two-nucleon scattering: merging chiral effective field theory with dispersion relations. https://doi.org/10.1140/epja%2Fi2013-13115-7

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