Zhi-Hui Guo, J. A. Oller, G. Rios
We consider nucleon-nucleon (NN) interactions from Chiral Effective Field Theory applying the N/D method. We calculate the discontinuity of the NN partial-wave amplitudes across the left-hand cut (LHC) by including one-pion exchange (OPE), once-iterated OPE and leading irreducible two-pion exchange (TPE) calculated in Chiral Perturbation Theory (ChPT). We discuss both uncoupled and coupled partial-waves. Phase shifts and mixing angles are typically rather well reproduced, and a clear improvement of the results obtained previously with only OPE is manifest. We also show that the contributions to the discontinuity across the LHC are amenable to a chiral expansion. Our method also establishes correlations between the S-wave effective ranges and scattering lengths based on unitarity, analyticity and chiral symmetry.
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http://arxiv.org/abs/1305.5790
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