https://doi.org/10.1140/epja/i2013-13115-7
Regular Article - Theoretical Physics
Two-nucleon scattering: Merging chiral effective field theory with dispersion relations
1
Institut für Theoretische Physik II, Fakultät für Physik und Astronomie, Ruhr-Universität Bochum, 44780, Bochum, Germany
2
SSC RF ITEP, Bolshaya Cheremushkinskaya 25, 117218, Moscow, Russia
3
GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291, Darmstadt, Germany
Received:
12
April
2013
Accepted:
21
August
2013
Published online:
16
September
2013
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 
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.
© SIF, Springer-Verlag Berlin Heidelberg, 2013
