668564
Medium effects on kaon and antikaon spectra in heavy-ion collisions.
In the linear chiral perturbation theory, both kaon and antikaon masses decrease in dense matter. There is also a repulsive vector potential for the kaon and an attractive one for the antikaon. With these effects included in the relativistic transport model, it is found that the slope parameter of the kaon kinetic energy distribution is larger than that of the antikaon. This is consistent with the experimental data from heavy-ion collisions in the Alternating Gradient Synchrotron experiments at Brookhaven.
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.
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.
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.
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.
28544953
Reply to "Parity violating asymmetries in the scattering of transversely polarized protons"
Experimental considerations usually favor measurements of the longitudinal rather than the irregular transverse analyzing power. This is particularly true for the case of the parity mixing in $^{14}\mathrm{N}$. Some typographical errors in our published expressions are corrected.
7056975
Appraisal of the Kuo-Herling shell-model interaction and application to A=210-212 nuclei.
Shell-model calculations are described for {ital A}=204--212 nuclei. These calculations use the Kuo-Herling realistic effective interactions for hole states and particle states relative to {sup 208}Pb. These interactions contain a bare part and a core-polarization contribution. The contribution of the core polarization was varied to find the best fit to the energy spectra of {ital A}=204--206 and 210--212 nuclei. This and other modifications to the Kuo-Herling interaction---designed to give better agreement with experimental energy spectra---are discussed. Aspects of the spectroscopy of {sup 211{minus}212}Pb, {sup 210}Po, {sup 212}Ra, {sup 210}Bi, and {sup 212}At are presented in order to illustrate the use of the Kuo-Herling particle interaction. Deficiencies in the Kuo-Herling interaction are described and the desirability and possibility of an improved calculation of the interaction is emphasized.
26272900
Limits on the presence of scalar and induced-scalar currents in superallowed beta decay.
Limits on the scalar and induced-scalar coupling constants are established from experimental {ital ft} values of superallowed Fermi transitions. The role of the uncertainties in the {ital ft} values is discussed, leading to minimal coupling strengths that can be extracted from {ital ft} values. The implications for the Kobayashi-Maskawa mixing angles are also discussed.
8524397
New Region of Deformation: The Neutron-Rich Sulfur Isotopes.
The energies and {ital B}({ital E}2;0{sub g.s.}{sup +}{r_arrow}2{sup +}{sub 1}) values for the lowest {ital J}{sup {pi}}=2{sup +} states in the neutron-rich radioactive nuclei {sup 38,40,42}S and {sup 44,46}Ar were measured via intermediate-energy Coulomb excitation. The results for {sup 40,42}S provide the first evidence of moderate deformation near {ital N}=28, while the effects of the {ital N}=28 shell closure persist in the {ital Z}=18 nucleus {sup 46}Ar. {copyright} {ital 1996 The American Physical Society.}
29372740
Strength functions and spreading widths of simple shell model configurations.
The exact solution of the many-body problem in the framework of the nuclear shell model with a realistic residual Hamiltonian makes it possible to study the fragmentation of simple configurations as a function of excitation energy and interaction strength. The analysis is performed for 839 states with quantum numbers {ital J}{sup {pi}}{ital T}=0{sup +}0 in a system of 12 valence particles within the {ital sd} shell. Our statistics allow us to establish the generic shape of the strength function in the region of strong mixing. For the realistic interaction, the strength function is close to Gaussian in the central part and has exponential wings. The spreading width is larger than predicted by the standard golden rule. At the artificially suppressed interaction strength, we recover the Breit-Wigner shape and the golden rule for the spreading width. The transition between these regimes agrees with theoretical considerations based on the idea of chaotic dynamics. {copyright} {ital 1996 The American Physical Society.}