Neutron-proton analyzing power at 50 MeV

We consider the two-nucleon system at next-to-next-to-next-to-leading order (N^3LO) in chiral effective field theory. The two-nucleon potential at N^3LO consists of one-, two- and three-pion exchanges and a set of contact interactions with zero, two and four derivatives. In addition, one has to take into account various isospin-breaking and relativistic corrections. We employ spectral function regularization for the multi-pion exchanges. Within this framework, it is shown that the three-pion exchange contribution is negligibly small. The low-energy constants (LECs) related to pion-nucleon vertices are taken consistently from studies of pion-nucleon scattering in chiral perturbation theory. The total of 26 four-nucleon LECs has been determined by a combined fit to some np and pp phase shifts from the Nijmegen analysis together with the nn scattering length. The description of nucleon-nucleon scattering and the deuteron observables at N^3LO is improved compared to the one at NLO and NNLO. The theoretical uncertainties in observables are estimated based on the variation of the cut-offs in the spectral function representation of the potential and in the regulator utilized in the Lippmann-Schwinger equation.Comment: 62 pp, 13 fig

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“…MeV. Data for the cross section are taken from [108,111] and for the analyzing power from [112,113,114,115,110]. For remaining notations see Fig.…”

Section: Effective Range Expansionmentioning

confidence: 99%

“…Figure10: np differential cross section and vector analyzing power at E lab = 50 MeV. Data for the cross section are taken from[108,111] and for the analyzing power from[112,113,114,115,110]. For remaining notations see Fig.9.…”

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confidence: 99%

The two-nucleon system at next-to-next-to-next-to-leading order

2005

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“…In order to 1.2 fm). Data for the cross section are taken from [109,110] and for the analyzing power from [111][112][113][114][115].…”

Section: Estimation Of the Theoretical Uncertaintymentioning

confidence: 99%

“…Finally, we emphasize that our results depend little on the specific choice of the regulator function. In order to Data for the cross section are taken from [109,110] and for the analyzing power from [111][112][113][114][115].…”

Section: Estimation Of the Theoretical Uncertaintymentioning

confidence: 99%

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Improved chiral nucleon-nucleon potential up to next-to-next-to-next-to-leading order

2015

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We present improved nucleon-nucleon potentials derived in chiral effective field theory up to nextto-next-to-next-to-leading order. We argue that the nonlocal momentum-space regulator employed in the two-nucleon potentials of Refs. [1,2] is not the most efficient choice, in particular since it affects the long-range part of the interaction. We are able to significantly reduce finite-cutoff artefacts by using an appropriate regularization in coordinate space which maintains the analytic structure of the amplitude. The new potentials do not require the additional spectral function regularization employed in Ref.[1] to cut off the short-range components of the two-pion exchange and make use of the low-energy constants ci and di determined from pion-nucleon scattering without any fine tuning. We discuss in detail the construction of the new potentials and convergence of the chiral expansion for two-nucleon observables. We also introduce a new procedure for estimating the theoretical uncertainty from the truncation of the chiral expansion that replaces previous reliance on cutoff variation.

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