42999511
Effect of chiral restoration on kaon production in relativistic heavy-ion collisions.
Kaon production from meson-meson annihilation is enhanced significantly because of the decrease of hadron masses in hot and dense matter as a result of the restoration of chiral symmetry. We show that this can lead to enhanced kaon yield in high-energy heavy-ion collisions.
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.
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.
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.
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.
37689024
Lowest order hadronic contribution to the muon g-2 value with systematic error correlations.
We have performed a new evaluation of the hadronic contribution to {ital a}{sub {mu}}=({ital g}{minus}2)/2 of the muon with explicit correlations of systematic errors among the experimental data on {sigma}({ital e}{sup +}{ital e}{sup {minus}}{r_arrow}hadrons). Our result for the lowest order hadronic vacuum polarization contribution is {ital a}{sub {mu}}{sup had}=702.6(7.8)(14.0){times}10{sup {minus}10} where the first error is statistical and the second is systematic. The total systematic error contributions from below and above {radical}{ital s}=1.4 GeV are (13.1){times}10{sup {minus}10} and (5.1){times}10{sup {minus}10}, respectively, and are hence dominated by the low energy region. Therefore, new measurements on {sigma}({ital e}{sup +}{ital e}{sup {minus}}{r_arrow}hadrons) below 1.4 GeV can significantly reduce the total error on {ital a}{sub {mu}}{sup had}. In particular, the effect on the total errors of new hypothetical data with 3{percent} statistical and 0.5{endash}1.0{percent} systematic errors is presented. {copyright} {ital 1996 The American Physical Society.}
20082114
Probe of the shell crossing at A=40 via beta decay: Experiment and theory.
The ..beta../sup -/ decays of /sup 35/P, /sup 37/S, /sup 38/S, and /sup 38/Cl were studied both experimentally and via shell-model calculations. The four decaying nuclei were formed by bombardment of 81% enriched /sup 36/S by triton and deuteron beams. Gamma-ray spectroscopy was carried out with Ge detectors, either bare or surrounded by a Compton suppression NaI(Tl) shield. One new Gamow-Teller decay was observed in /sup 35/P decay, and one new first-forbidden decay was observed in /sup 38/S decay. Otherwise ..gamma..-ray measurements of E/sub ..gamma../ and I-/sub ..gamma../ (and limits on I/sub ..gamma../ for unobserved transitions) were improved significantly over previous results. Shell-model studies were undertaken in order to bring these beta decay results to bear on an understanding of the shell structure in the (sd) to (fp) transition region at A = 40. An interaction was constructed in the 1d/sub 5/2/, 1d/sub 3/2/, 2s/sub 1/2/, 1f/sub 7/2/, 1f/sub 5/2/, 1p/sub 3/2/, 1p/sub 1/2/ model space. This interaction started from the Wildenthal ''USD'' (sd) interaction and the van Hees-Glaudemans (fp) interaction, which were connected by the cross-shell Millener-Kurath interaction. Certain important two-body matrix elements and single-particle energies were adjusted to fit experimental binding energies in A = 40, 41, 42.more » This interaction was then used to calculate level spectra for the daughter nuclei /sup 35/S, /sup 37/Cl, /sup 38/Cl, and /sup 38/Ar as well as Gamow-Teller and unique first-forbidden beta decays leading to these nuclei. The techniques used in these relatively large scale calculations are discussed in detail, as are the results.« less
19945972
Corrections to the Fermi matrix element for superallowed beta decay.
Corrections to the Fermi matrix element for superallowed transitions due to isospin nonconservation are reexamined. The sources of theoretical uncertainty and the possibility of a previously neglected correction based on the mismatch between the spectator nucleons are investigated. The consequences to the conserved-vector-current hypothesis and the Kobayashi-Maskawa mixing angles are discussed.
15583656
Black hole pair creation and the entropy factor.
It is shown that in the instanton approximation the rate of creation of black holes is always enhanced by a factor of the exponential of the black hole entropy relative to the rate of creation of compact matter distributions (stars). This result holds for any generally covariant theory of gravitational and matter fields that can be expressed in Hamiltonian form. It generalizes the result obtained previously for the pair creation of magnetically charged black holes by a magnetic field in Einstein--Maxwell theory. The particular example of pair creation of electrically charged black holes by an electric field in Einstein--Maxwell theory is discussed in detail.
11983780
Is there large weak mixing in heavy nuclei?
Recent results in parity non-conserving neutron-nucleus scattering show a tendency for the parity non-conserving effects to predominantly have the same sign. Explanations of this phenomenon all require a weak matrix element between single-particle levels in heavy nuclei to be [similar to]100 eV. This paper contains a discussion of this effect and how the same phenomenon will manifest itself in other systems. The gamma decay of [sup 207]Pb is given as an example of a system where the weak matrix element between single-particle levels in a heavy nucleus can be measured directly.