12038680
Strangeness condensation and cooling of neutron stars.
Possible effects of strangeness condensation, which has been estimated to occur in dense neutron matter at densities of 2.3--3.0 times nuclear matter density, are calculated with special reference to the cooling of the neutron star probably formed in SN1987A. Although the center of the neutron star will cool much faster in the presence of strangeness condensation than through conventional mechanisms, down to Tapprox.2 x 10/sup 8/ K at the present time, the heat conductivity of the neutron star is such that it will take at least a few tens of years for effects of this drop in temperature to reach the surface of the neutron star and be observable.
120275311
Kaon condensation, black holes, and cosmological natural selection.
It is argued that a well-measured double neutron-star binary in which the two neutron stars are more than 4% different from each other in mass or a massive neutron star with mass M≥ 2M o would put in serious doubt or simply falsify the following chain of predictions: (1) a nearly vanishing vector meson mass at chiral restoration, (2) kaon condensation at a density n ∼ 3n o , (3) the Brown-Bethe maximum neutron-star mass M maX ≈1.5M ⊙ , and (4) Smolin's "cosmological natural selection" hypothesis.
119072699
Nuclear matter with Brown–Rho-scaled Fermi liquid interactions
Abstract We present a description of symmetric nuclear matter within the framework of Landau Fermi liquid theory. The low momentum nucleon–nucleon interaction V low - k is used to calculate the effective interaction between quasiparticles on the Fermi surface, from which we extract the quasiparticle effective mass, the nuclear compression modulus, the symmetry energy, and the anomalous orbital gyromagnetic ratio. The exchange of density, spin, and isospin collective excitations is included through the Babu–Brown induced interaction, and it is found that in the absence of three-body forces the self-consistent solution to the Babu–Brown equations is in poor agreement with the empirical values for the nuclear observables. This is improved by lowering the nucleon and meson masses according to Brown–Rho scaling, essentially by including a scalar tadpole contribution to the meson and nucleon masses, as well as by scaling g A . We suggest that modifying the masses of the exchanged mesons is equivalent to introducing a short-range three-body force, and the net result is that the Brown–Rho double decimation [G.E. Brown, M. Rho, Phys. Rep. 396 (2004) 1] is accomplished all at once.
117511063
The Physics of Supernovae and the Equation of State of Dense Nuclear Matter
The collapse of large stars leading to supernova explosions continues until the core reaches supranuclear densities. The large energy of SN(1987)A (Shelton) implies a soft equation of state, which makes it possible to transfer a large amount of energy from the core to the shock wave which carries through the explosion. At nuclear matter density the Landau forward scattering sum rule puts constraints on the Fermi liquid parameters strongly favouring a low-compression modulus. Whereas conventional nuclear physics calculations give a stiffer equation of state than required for supernovae at higher densities, it is pointed out that these do not include meson masses which decrease with increasing nuclear-matter density. This decrease in meson masses is implied by chiral symmetry. With decreasing meson masses the standard mechanism for saturation disappears, and saturation must be obtained from higher-order loops. These give the possibility, at least, of obtaining a low-compression modulus and soft equation of state at higher densities, because of their smooth dependence on density. In any case, this soft EOS seems to be required by the supernova explosion.
15066887
Renormalization group approach to neutron matter: quasiparticle interactions, superfluid gaps and the equation of state
Renormalization group methods can be applied to the nuclear many-body problem using the approach proposed by Shankar. We start with the two-body low momentum interaction Vlowk and use the RG flow from the particle–hole channels to calculate the full scattering amplitude in the vicinity of the Fermi surface. This is a new straightforward approach to the many-body problem which is applicable also to condensed matter systems without long-range interactions, such as liquid 3He. We derive the one-loop renormalization group equations for the quasiparticle interaction and the scattering amplitude at zero temperature. The RG presents an elegant method to maintain all momentum scales and preserve the antisymmetry of the scattering amplitude. As a first application we solve the RG equations for neutron matter. The resulting quasiparticle interaction includes effects due to the polarization of the medium, the so-called induced interaction of Babu and Brown. We present results for the Fermi liquid parameters, the equation of state of neutron matter and the 1S0 superfluid pairing gap.
122541063
Relativistic effects in nuclear physics
Relativistic effects in nuclear physics are discussed. Very important effects stem from the lowering of the nucleon effective mass m* by the attractive scalar mean field. Spontaneous symmetry breaking by this field in the vacuum was originally responsible for the nucleon mass. Implications implied by the quark/gluon phase transition for this scalar mean field is discussed.
19989163
Nucleon scattering from 34S and the relative sign of neutron and proton transition matrix elements for the (0-->22+) transition.
Data obtained by scattering 29.8 MeV protons and 21.7 MeV neutrons from $^{34}\mathrm{S}$ are used in a consistent analysis to obtain values and relative signs for proton (${M}_{\mathrm{p}}$) and neutron (${M}_{\mathrm{n}}$) multiple matrix elements for E2 transitions to the first three ${2}^{+}$ states in $^{34}\mathrm{S}$. The data for the ${0}^{+}$(g.s.)\ensuremath{\rightarrow}${2}_{2}^{+}$(3.30 MeV) transition are consistent only with the assumption of the same relative sign of ${M}_{\mathrm{p}}$ and ${M}_{\mathrm{n}}$. .AE
5059193
High-energy reaction cross sections of light nuclei.
The high-energy reaction cross sections of Li and Be isotopes are calculated using a simplified Glauber model and densities constrained by the empirical binding energies. We find excellent agreement with experiment, reproducing the large increase for the most neutron-rich nuclei.
39044560
Neutron halos in the Na isotopes.
The neutron and proton density distributions of the Na isotopes out to the proton and neutron drip lines are calculated in the spherical Hartree-Fock model with a wide variety of density-dependent Skyrme interactions. The results are compared to recent experimental data for the interaction cross sections and for the rms radii. We discuss the role of the deformed intruder states and the problems associated with predicting the location of the neutron drip line for this mass region. {copyright} {ital 1996 The American Physical Society.}
9453919
New tools for solving the solar-neutrino problem.
Neutrino (..nu..) excitation of nuclear levels (NUEX) via neutral currents is shown to be crucially important to the solar-..nu.. problem as a method of detecting ..nu..'s regardless of flavor. We examine /sup 11/B, /sup 40/Ar, and /sup 35/Cl as NUEX targets. The /sup 11/B system offers means for concurrent solar-..nu.. spectroscopy by NUEX and by charged-current ..nu../sub e/ capture with a set of differing thresholds. It promises a self-contained solution to the solar-..nu.. problem as well as key probes for revealing the structure of resonant flavor and nonflavor ..nu.. oscillations in the sun. This approach may be feasible in an ICARUS-type underground experiment.
34063467
Simple relation for alpha decay half-lives.
The experimental values of ${\mathrm{log}}_{10}$${\mathit{T}}_{1/2}$(sec) plotted vs ${\mathit{Z}}_{\mathit{d}}^{0.6}$/ \ensuremath{\surd}${\mathit{Q}}_{\mathrm{\ensuremath{\alpha}}}$ are shown to fall on a nearly universal straight line with ${\mathrm{log}}_{10}$${\mathit{T}}_{1/2}$(sec)=(9.54${\mathit{Z}}_{\mathit{d}}^{0.6}$/ \ensuremath{\surd}${\mathit{Q}}_{\mathrm{\ensuremath{\alpha}}}$)-51.37, where ${\mathit{Z}}_{\mathit{d}}$ is the charge number of the daughter nucleus and ${\mathit{Q}}_{\mathrm{\ensuremath{\alpha}}}$ is expressed in units of MeV. This behavior also numerically comes out of the semiclassical WKB calculation of the barrier penetration factor. The fine structure in the ratio of experiment over theory is briefly discussed.