845 research outputs found
Solar neutrinos: global analysis and implications for SNO
We present a global analysis of all the available solar neutrino data
treating consistently the 8B and hep neutrino fluxes as free parameters. The
analysis reveals at 99.7% C.L. eight currently-allowed discrete regions in
two-neutrino oscillation space, five regions corresponding to active neutrinos
and three corresponding to sterile neutrinos. Most of the allowed solutions are
robust with respect to changes in the analysis procedure, but the traditional
vacuum solution is fragile. The globally-permitted range of the 8B neutrino
flux, 0.45 to 1.95 in units of the BP2000 flux, is comparable to the 3 sigma
range allowed by the standard solar model. We discuss the implications for SNO
of a low mass, Delta m^2 ~ 6 times 10^{-12} eV^2, vacuum oscillation solution,
previously found by Raghavan, and by Krastev and Petcov, but absent in recent
analyses that included Super-Kamiokande data. For the SNO experiment, we
present refined predictions for the charged-current rate and the ratio of the
neutral-current rate to charged-current rate. The predicted charged-current
rate can be clearly distinguished from the no-oscillation rate only for the LMA
solution. The predicted ratio of the neutral-current rate to charged-current
rate is distinguishable from the no-oscillation ratio for the LMA, SMA, LOW,
and VAC solutions for active neutrinos.Comment: viewgraphs and related material at http://www.sns.ias.ed
Predicting the single-proton/neutron potentials in asymmetric nuclear matter
We discuss the one-body potentials for protons and neutrons obtained from
Dirac-Brueckner-Hartree-Fock calculations of neutron-rich matter, in particular
their dependence upon the degree of proton/neutron asymmetry. The closely
related symmetry potential is compared with empirical information from the
isovector component of the nuclear optical potential.Comment: 9 pages, 6 figures. Minor revisions, added comments, reference
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