36218377
Spin of the proton and the chiral bag.
Measurement of the spin carried by the quarks in the proton can be very important in distinguishing between low-energy models of the hadron. Topological soliton models have rather little or no spin in the quarks, in agreement with present experimental indications.
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.
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.
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.
2057519
Single-nucleon pickup spectroscopic factors for levels in 30Si and 30P and the D state of three-nucleon systems.
Angular distributions of differential cross sections and vector and tensor analyzing powers have been measured for transitions in /sup 31/P(d,/sup 3/He)/sup 30/Si and /sup 31/P(d,t)/sup 30/P reactions at E/sub d/approx. =16 Mev. Exact, finite-range distorted-wave Born-approximation analyses have been performed using S- and D-state amplitudes for the three-nucleon systems. Calculations have also been carried out by incorporating realistic three-body wave functions. A j dependence in tensor analyzing powers observed for the first time in (d,/sup 3/He) and (d,t) reactions, can be reproduced in distorted-wave Born approximation calculations only by including a D-state amplitude for three-nucleon systems. We find that the tensor analyzing powers for j = l/sub 1/+(1/2 transfers exhibit significantly more pronounced D-state effects than those for j = l/sub 1/-(1/2 transfers. The analyzing powers along with the differential cross sections have been used to extract spectroscopic factors for the low-lying levels in /sup 30/Si and /sup 30/P, and the results have been compared with recent sd--shell-model predictions.
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
31262338
Mass systematics for A=29-44 nuclei: The deformed A~32 region.
Further evidence for the presence of an anomaly in binding energies for the island of inversion'' centered at {ital Z}=11, {ital N}=21 is obtained by comparison of shell-model calculations to experiment. The calculations were done with a shell-model interaction that is applicable to nuclei with active valence nucleons in both the (1{ital s},0{ital d}) and (0{ital f},1{ital p}) major shells. This interaction is described in detail as are its predictions for binding energies and energy spectra of {ital Z}=8--20, {ital N}=18--25 nuclei. These calculations provide the background for the exploration of the island of inversion.'' The extent of the island'' and the magnitude of the anomaly is explored by calculating the binding energies of 2{h bar}{omega} excitations of neutrons from the (1{ital s},0{ital d}) shell to the (0{ital f},1{ital p}) shell relative to the 0{h bar}{omega} ground state. The reason why mixed (0+2){h bar}{omega} calculations are not considered reliable is addressed. Truncation schemes and a weak-coupling approximation are used to extend the range of the calculations. It is found that for {ital Z}=10--12, {ital N}=20--22 (and possibly {ital N}{gt}22) nuclei the lowest 2{h bar}{omega} state is more bound than the 0{h bar}{omega} ground state. The role of odd {ital n}more » {ital n}{h bar}{omega} excitations is considered and it is found that the 1{h bar}{omega} ground state always lies below that of 3{h bar}{omega}, and for {ital N}=19, 21, and 23, the lowest 1{h bar}{omega} state is in close competition with 2{h bar}{omega} for the lowest binding energy. Collectivity is considered via {ital E}2 observables and energy spectra for the 2{h bar}{omega} ground-state bands. The reason for the existence of the island'' is discussed.« less
26550883
Relationship between Gamow-Teller transition probabilities and (p,n) cross sections at small momentum transfers.
Gamow-Teller transition probabilities are extracted for eight nuclei with masses between A = 13 and A = 39 from medium-energy (p,n) reactions via the distorted-wave impulse approximation, and compared with experimental ..beta..-decay and with free-nucleon transition probabilities. These comparisons indicate strongly that the renormalization of the Gamow-Teller operator needed for (p,n) reactions on finite nuclei is different from that needed for ..beta.. decay.