Abstract
Nucleon-nucleon scattering is studied by applying an approach based on the method and chiral perturbation theory (ChPT), whose dynamical input per partial wave consists of the imaginary part of the partial-wave amplitude along the left-hand cut. The latter is calculated in one-loop ChPT up to and including next-to-next-to-leading order (NNLO). A power counting for the subtraction constants is established, which is appropriate for those subtractions attached to both the left- and the right-hand cuts. A quite good reproduction of the Nijmegen partial-wave analysis phase shifts and mixing angles results, which implies a steady improvement in the accurateness achieved by increasing the chiral order in the calculation of the dynamical input. I discuss that it is not necessary to fine tune the chiral counterterms determined from pion-nucleon scattering to agree with data, but instead one should perform the iteration of two-nucleon intermediate states in a well-defined way so as to keep proper unitarity and analyticity. It is also confirmed at NNLO the long-range correlations between the -wave effective ranges and scattering lengths, when employing only once-subtracted dispersion relations, that hold up to around 10% when compared with experimental values.
- Received 14 February 2014
- Revised 9 September 2015
DOI:https://doi.org/10.1103/PhysRevC.93.024002
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