Comparative study of He6 β-decay based on different similarity-renormalization-group evolved chiral interactions

A. Gnech, L. E. Marcucci, R. Schiavilla, and M. Viviani
Phys. Rev. C 104, 035501 – Published 14 September 2021

Abstract

We report on a study of the Gamow-Teller matrix element contributing to He6β decay with similarity renormalization group (SRG) versions of momentum- and configuration-space two-nucleon interactions. These interactions are derived from two different formulations of chiral effective field theory (χEFT)—without and with the explicit inclusion of Δ isobars. We consider evolution parameters ΛSRG in the range between 1.2 and 2.0 fm1 and, for the Δ-less case, also the unevolved (bare) interaction. The axial current contains one- and two-body terms, consistently derived at tree level (no loops) in the two distinct χEFT formulations we have adopted here. The He6 and Li6 ground-state wave functions are obtained from hyperspherical-harmonics (HH) solutions of the nuclear many-body problem. In A=6 systems, the HH method is limited at present to treat only two-body interactions and non-SRG evolved currents. Our results exhibit a significant dependence on ΛSRG of the contributions associated with two-body currents, suggesting that a consistent SRG-evolution of these is needed in order to obtain reliable estimates. We also show that the contributions from one-pion-exchange currents depend strongly on the model (chiral) interactions and on the momentum- or configuration-space cutoffs used to regularize them. These results might prove helpful in clarifying the origin of the sign difference recently found in no-core-shell-model and quantum Monte Carlo calculations of the He6 Gamow-Teller matrix element.

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  • Received 15 June 2021
  • Accepted 25 August 2021

DOI:https://doi.org/10.1103/PhysRevC.104.035501

©2021 American Physical Society

Physics Subject Headings (PhySH)

  1. Research Areas
  1. Properties
Nuclear Physics

Authors & Affiliations

A. Gnech1, L. E. Marcucci2,3, R. Schiavilla1,4, and M. Viviani3

  • 1Theory Center, Jefferson Lab, Newport News, Virginia 23606, USA
  • 2Department of Physics, Università di Pisa, 56127 Pisa, Italy
  • 3INFN-Pisa, 56127 Pisa, Italy
  • 4Department of Physics, Old Dominion University, Norfolk, Virginia 23529, USA

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Issue

Vol. 104, Iss. 3 — September 2021

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