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Title: Halo effective field theory constrains the solar 7Be + p → 8B + γ rate

In this study, we report an improved low-energy extrapolation of the cross section for the process 7Be(p,γ) 8B, which determines the 8B neutrino flux from the Sun. Our extrapolant is derived from Halo Effective Field Theory (EFT) at next-to-leading order. We apply Bayesian methods to determine the EFT parameters and the low-energy S-factor, using measured cross sections and scattering lengths as inputs. Asymptotic normalization coefficients of 8B are tightly constrained by existing radiative capture data, and contributions to the cross section beyond external direct capture are detected in the data at E < 0.5 MeV. Most importantly, the S-factor at zero energy is constrained to be S(0) = 21.3 ± 0.7 eV b, which is an uncertainty smaller by a factor of two than previously recommended. That recommendation was based on the full range for S(0) obtained among a discrete set of models judged to be reasonable. In contrast, Halo EFT subsumes all models into a controlled low-energy approximant, where they are characterized by nine parameters at next-to-leading order. These are fit to data, and marginalized over via Monte Carlo integration to produce the improved prediction for S(E).
ORCiD logo [1] ;  [2] ;  [3]
  1. Univ. of Washington, Seattle, WA (United States); Ohio Univ., Athens, OH (United States)
  2. Univ. of South Carolina, Columbia, SC (United States); San Diego State Univ., San Diego, CA (United States); Ohio Univ., Athens, OH (United States)
  3. Ohio Univ., Athens, OH (United States)
Publication Date:
Grant/Contract Number:
FG02-93ER40756; FG02-93ER-40756; FG02-97ER-41014; SC 0010 300; FG02-09ER41621
Published Article
Journal Name:
Physics Letters. Section B
Additional Journal Information:
Journal Volume: 751; Journal Issue: C; Journal ID: ISSN 0370-2693
Research Org:
Ohio Univ., Athens, OH (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1240089