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Title: Comparative study of He 6 β -decay based on different similarity-renormalization-group evolved chiral interactions

Journal Article · · Physical Review C
ORCiD logo [1];  [2];  [3];  [4]
  1. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
  2. Univ. of Pisa (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Pisa (Italy)
  3. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Old Dominion Univ., Norfolk, VA (United States)
  4. Istituto Nazionale di Fisica Nucleare (INFN), Pisa (Italy)
+ Show Author Affiliations

We report on a study of the Gamow-Teller matrix element contributing to $${}^6$$He $$\beta$$-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 ($$\chi$$EFT) -- without and with the explicit inclusion of $$\Delta$$-isobars. We consider evolution parameters $$\Lambda_{\rm SRG}$$ in the range between 1.2 and 2.0 fm$$^{-1}$$ and, for the $$\Delta$$-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 $$\chi$$EFT formulations we have adopted here. The $${}^6$$He and $${}^6$$Li 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 $$\Lambda_{\text{SRG}}$$ 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 $${}^6$$He Gamow-Teller matrix element.

Research Organization:
Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Nuclear Physics (NP)
Grant/Contract Number:
AC05-06OR23177
OSTI ID:
1820928
Report Number(s):
JLAB-THY-21-3422; DOE/OR/-23177-5240; arXiv:2106.07439; TRN: US2214304
Journal Information:
Physical Review C, Vol. 104, Issue 3; ISSN 2469-9985
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English

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