Effects of. Delta. -isobar degrees of freedom on low-energy electroweak transitions in few-body nuclei
- Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
- Department of Physics, University of Illinois, Urbana, Illinois 61801 (United States)
- Theory Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
Variational wave functions with {Delta}-isobar components are used to study trinucleon magnetic moments, the Gamow-Teller matrix element of tritium {beta} decay, thermal neutron radiative capture on {sup 3}He, and low-energy proton weak capture on {sup 3}He. The {Delta}-isobar components are generated by transition correlation operators acting on realistic nuclear wave functions. These correlations are obtained from a fit to exact two-body ground-state and low-energy scattering solutions for the Argonne {ital v}{sub 28} and {ital v}{sub 28{ital Q}} interaction models, which include {Delta}-isobar degrees of freedom. Contributions of {Delta} isobars to electroweak current operators appear at the one-body level in this formalism. Their effect on low-energy electroweak transitions is significantly smaller than that obtained in perturbation theory analyses, where {Delta}-isobar effects are commonly subsumed into effective two-body current operators. The resulting theoretical cross section for thermal neutron radiative capture on {sup 3}He is {approx}86 {mu}b, compared to an experimental value of 55{plus minus}3 {mu}b; the astrophysical {ital S} factor for proton weak capture on {sup 3}He is predicted to be in the range (1.4--3.2){times}10{sup {minus}23} MeV b.
- DOE Contract Number:
- W-31-109-ENG-38
- OSTI ID:
- 7286557
- Journal Information:
- Physical Review, C (Nuclear Physics); (United States), Vol. 45:6; ISSN 0556-2813
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
HELIUM 3 TARGET
NEUTRON REACTIONS
CAPTURE
GAMMA RADIATION
ISOBAR MODEL
NUCLEAR FORCES
TOTAL CROSS SECTIONS
WAVE FUNCTIONS
WEINBERG-SALAM GAUGE MODEL
BARYON REACTIONS
CROSS SECTIONS
ELECTROMAGNETIC RADIATION
FIELD THEORIES
FUNCTIONS
HADRON REACTIONS
IONIZING RADIATIONS
MATHEMATICAL MODELS
NUCLEAR REACTIONS
NUCLEON REACTIONS
PARTICLE MODELS
RADIATIONS
TARGETS
UNIFIED GAUGE MODELS
UNIFIED-FIELD THEORIES
663430* - Nucleon-Induced Reactions & Scattering- (1992-)
663510 - Nuclear Mass Ranges- A=1-5- (1992-)