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Nuclear Theory·nucl-th

Friday·August 11, 2017

6 papers—2 primary·4 cross-listed

All6Primary2Cross-lists4
  1. 01

    Analyzing the Fierz Rearrangement Freedom for Local Chiral Two-Nucleon Potentials

    L. Huth · I. Tews · J. E. Lynn · A. Schwenk

    Chiral effective field theory is a framework to derive systematic nuclear interactions. It is based on the symmetries of quantum chromodynamics and includes long-range pion physics explicitly, while shorter-range physics is expanded in a general operator basis. The number of low-energy couplings at a particular order in the expansion can be reduced by exploiting the fact that nucleons are fermions and therefore obey the Pauli exclusion principle. The antisymmetry permits the selection of a subset of the allowed contact operators at a given order. When local regulators are used for these short-range interactions, however, this "Fierz rearrangement freedom" is violated. In this paper, we investigate the impact of this violation at leading order (LO) in the chiral expansion. We construct LO and next-to-leading order (NLO) potentials for all possible LO-operator pairs and study their reproduction of phase shifts, the He ground-state energy, and the neutron-matter energy at different densities. We demonstrate that the Fierz rearrangement freedom is partially restored at NLO where subleading contact interactions enter. We also discuss implications for local chiral three-nucleon interactions.

    nucl-thnucl-exPRC(2017)·46 citations
  2. 02

    Scale dependence of deuteron electrodisintegration

    Sushant N. More · Scott K. Bogner · Richard J. Furnstahl

    A model calculation of deuteron electrodisintegration is used to explore renormalization group (RG) scale dependence for knock-out reactions. When evolved to different resolutions with the similarity RG (SRG), the initial deuteron wave function, the current operator, and the final state interactions (FSI) are all modified, but how they combine depends strongly on the kinematic region. In some regions, for example, the FSI are largely unaffected by evolution, while elsewhere FSI are greatly reduced. For certain kinematics, the impulse approximation at a high RG resolution gives an intuitive picture in terms of a one-body current breaking up a short-range correlated neutron-proton pair, although FSI distort this simple picture. With evolution to low resolution, however, the cross section is unchanged but a very different and arguably simpler intuitive picture emerges, with the evolved current efficiently represented at low momentum through derivative expansions or low-rank singular value decompositions. A consequence is that intuition about physics such as the role of short-range correlations or -state mixing in particular kinematic regimes can be strongly scale dependent.

    nucl-thPRC(2017)·31 citations

Affiliations

first authorsco-authorsvia INSPIRE