Neutron-proton correlations in an exactly solvable model
Abstract
We examine isovector and isoscalar neutron-proton correlations in an exactly solvable model based on the algebra SO(8). We look particularly closely at Gamow-Teller strength and double {beta} decay, both to isolate the effects of the two kinds of pairing and to test two approximation schemes: the renormalized neutron-proton quasiparticle random phase approximation (QRPA) and generalized BCS theory. When isoscalar pairing correlations become strong enough a phase transition occurs and the dependence of the Gamow-Teller {beta}{sup +} strength on isospin changes in a dramatic and unfamiliar way, actually increasing as neutrons are added to an N=Z core. Renormalization eliminates the well-known instabilities that plague the QRPA as the phase transition is approached, but only by unnaturally suppressing the isoscalar correlations. Generalized BCS theory, on the other hand, reproduces the Gamow-Teller strength more accurately in the isoscalar phase than in the usual isovector phase, even though its predictions for energies are equally good everywhere. It also mixes T=0 and T=1 pairing, but only on the isoscalar side of the phase transition. {copyright} {ital 1997} {ital The American Physical Society}
- Authors:
-
- Department of Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina 27599 (United States)
- Bartol Research Institute, University of Delaware, Newark, Deleware 19716 (United States)
- Institute of Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Sofia-1784 (Bulgaria)
- Department of Physics, Caltech, 161-33, Pasadena, California 91125 (United States)
- Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Cientificas, Serrano 123, 28006 Madrid (Spain)
- Publication Date:
- Research Org.:
- California Institute of Technology (CalTech), Pasadena, CA (United States)
- OSTI Identifier:
- 541980
- DOE Contract Number:
- FG03-88ER40397; FG05-94ER40827
- Resource Type:
- Journal Article
- Journal Name:
- Physical Review, C
- Additional Journal Information:
- Journal Volume: 55; Journal Issue: 4; Other Information: PBD: Apr 1997
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 66 PHYSICS; NUCLEAR FORCES; NUCLEON-NUCLEON POTENTIAL; PROTON-NEUTRON INTERACTIONS; CORRELATIONS; GAMOW-TELLER RULES; DOUBLE BETA DECAY; SO-8 GROUPS; RENORMALIZATION; QUASI PARTICLES; RANDOM PHASE APPROXIMATION; BCS THEORY; PAIRING INTERACTIONS; PHASE TRANSFORMATIONS; ISOSPIN; INSTABILITY
Citation Formats
Engel, J, Pittel, S, Stoitsov, M, Vogel, P, and Dukelsky, J. Neutron-proton correlations in an exactly solvable model. United States: N. p., 1997.
Web. doi:10.1103/PhysRevC.55.1781.
Engel, J, Pittel, S, Stoitsov, M, Vogel, P, & Dukelsky, J. Neutron-proton correlations in an exactly solvable model. United States. https://doi.org/10.1103/PhysRevC.55.1781
Engel, J, Pittel, S, Stoitsov, M, Vogel, P, and Dukelsky, J. 1997.
"Neutron-proton correlations in an exactly solvable model". United States. https://doi.org/10.1103/PhysRevC.55.1781.
@article{osti_541980,
title = {Neutron-proton correlations in an exactly solvable model},
author = {Engel, J and Pittel, S and Stoitsov, M and Vogel, P and Dukelsky, J},
abstractNote = {We examine isovector and isoscalar neutron-proton correlations in an exactly solvable model based on the algebra SO(8). We look particularly closely at Gamow-Teller strength and double {beta} decay, both to isolate the effects of the two kinds of pairing and to test two approximation schemes: the renormalized neutron-proton quasiparticle random phase approximation (QRPA) and generalized BCS theory. When isoscalar pairing correlations become strong enough a phase transition occurs and the dependence of the Gamow-Teller {beta}{sup +} strength on isospin changes in a dramatic and unfamiliar way, actually increasing as neutrons are added to an N=Z core. Renormalization eliminates the well-known instabilities that plague the QRPA as the phase transition is approached, but only by unnaturally suppressing the isoscalar correlations. Generalized BCS theory, on the other hand, reproduces the Gamow-Teller strength more accurately in the isoscalar phase than in the usual isovector phase, even though its predictions for energies are equally good everywhere. It also mixes T=0 and T=1 pairing, but only on the isoscalar side of the phase transition. {copyright} {ital 1997} {ital The American Physical Society}},
doi = {10.1103/PhysRevC.55.1781},
url = {https://www.osti.gov/biblio/541980},
journal = {Physical Review, C},
number = 4,
volume = 55,
place = {United States},
year = {Tue Apr 01 00:00:00 EST 1997},
month = {Tue Apr 01 00:00:00 EST 1997}
}