Supernova neutrino scattering rates reduced by nucleon spin fluctuations: Perturbative limit
- Max-Planck-Institut fuer Physik, Foehringer Ring 6, 80805 Muenchen (Germany)
- Bartol Research Institute, University of Delaware, Newark, Delaware 19716 (United States)
- Department of Astronomy and Astrophysics, The University of Chicago, Chicago, Illinois 60637-1433 (United States)
In a nuclear medium, spin-dependent forces cause the nucleon spins to fluctuate with a rate {Gamma}{sub {sigma}}. We have previously shown that as a consequence the effective axial-vector current neutrino-nucleon scattering cross section is reduced. Here, we calculate this reduction explicitly in the perturbative limit {Gamma}{sub {sigma}}{lt}{ital T}. By virtue of an exact sum rule of the spin-density structure function, we express the modified cross section in terms of the matrix element for neutrino-nucleon scattering in the presence of a spin-dependent nuclear potential. This representation allows for a direct comparison with, and confirmation of, Sawyer{close_quote}s related perturbative result. In a supernova core with a typical temperature {ital T}=10MeV, the perturbative limit is relevant for densities {rho}{approx_lt}10{sup 13} g cm{sup {minus}3} and thus applies around the neutrino sphere. There, the cross-section reduction is of order a few percent and thus not large; however, a new mode of energy transfer between neutrinos and nucleons is enabled which may be important for neutrino spectra formation. We derive an analytic perturbative expression for the rate of energy transfer. {copyright} {ital 1996 The American Physical Society.}
- DOE Contract Number:
- AC02-78ER05007
- OSTI ID:
- 286850
- Journal Information:
- Physical Review, D, Vol. 54, Issue 4; Other Information: PBD: Aug 1996
- Country of Publication:
- United States
- Language:
- English
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