58 research outputs found
Sensitivity analysis of random two-body interactions
The input to the configuration-interaction shell model includes many dozens
or hundreds of independent two-body matrix elements. Previous studies have
shown that when fitting to experimental low-lying spectra, the greatest
sensitivity is to only a few linear combinations of matrix elements. Here we
consider interactions drawn from the two-body random ensemble, or TBRE, and
find that the low-lying spectra are also most sensitive to only a few linear
combinations of two-body matrix elements, in a fashion nearly indistinguishable
from an interaction empirically fit to data. We find in particular the spectra
for both the random and empirical interactions are sensitive to similar matrix
elements, which we analyze using monopole and contact interactions.Comment: 8 pages, 3 figure
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
Towards Understanding Astrophysical Effects of Nuclear Symmetry Energy
Determining the Equation of State (EOS) of dense neutron-rich nuclear matter
is a shared goal of both nuclear physics and astrophysics. Except possible
phase transitions, the density dependence of nuclear symmetry \esym is the most
uncertain part of the EOS of neutron-rich nucleonic matter especially at
supra-saturation densities. Much progresses have been made in recent years in
predicting the symmetry energy and understanding why it is still very uncertain
using various microscopic nuclear many-body theories and phenomenological
models. Simultaneously, significant progresses have also been made in probing
the symmetry energy in both terrestrial nuclear laboratories and astrophysical
observatories. In light of the GW170817 event as well as ongoing or planned
nuclear experiments and astrophysical observations probing the EOS of dense
neutron-rich matter, we review recent progresses and identify new challenges to
the best knowledge we have on several selected topics critical for
understanding astrophysical effects of the nuclear symmetry energy.Comment: 77 pages. Invited Review Article, EPJA (2019) in pres
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