121153627
Properties and structure of N = Z nuclei within relativistic mean field theory
The axially deformed relativistic mean field theory with the force NLSH has been performed in the blocked BCS approximation to investigate the properties and structure of N = Z nuclei from Z = 20 to Z = 48. Some ground state quantities such as binding energies, quadrupole deformations, one/two-nucleon separation energies, root-mean-square (rms) radii of charge and neutron, and shell gaps have been calculated. The results suggest that large deformations can be found in medium-heavy nuclei with N = Z = 38–42. The charge and neutron rms radii increase rapidly beyond the magic number N = Z = 28 until Z = 42 with increasing nucleon number, which is similar to isotope shift, yet beyond Z = 42, they decrease dramatically as the structure changes greatly from Z = 42 to Z = 43. The evolution of shell gaps with proton number Z can be clearly observed. Besides the appearance of possible new shell closures, some conventional shell closures have been found to disappear in some region. In addition, we found that the Coulomb interaction is not strong enough to breakdown the shell structure of protons in the current region.
119275256
Effects of the magnetic field on the spallation reaction implemented by BUU coupled with a phase-space coalescence afterburner
Based on the Boltzmann-Uehling-Uhlenbeck (BUU) transport model coupled with a phase-space coalescence afterburner, the spallation reaction p + 197Au at the incident beam energy Ebeam = 800 MeV/nucleon is studied. We find that the number of test particles per nucleon has minor effects on the neutron-to-proton ratio (n/p) of the produced heavier fragments while it affects much their yields. The external strong magnetic field affects the production of heavier fragments more than the n/p of produced fragments. The n/p of free nucleons is greatly affected by the strong magnetic field, especially for the nucleons with lower energies.
119110371
Three-body force effect on off-shell mass operator and spectral functions in nuclear matter
Within the framework of the Brueckner theory, the off-shell behaviors of the mass operator $M(k,\omega)=V(k,\omega)+iW(k,\omega)$, i.e., its dependence upon the momentum $k$ and upon the nucleon frequency $\omega$, are investigated by including nuclear three-body force (TBF). The first two terms of the hole-line expansion of the mass operator are taken into account. The TBF effects on their off-shell properties are discussed. A comparison is made between the on-shell and off-shell values of $M_{1}$. The nucleon spectral function and nucleon momentum distribution are also calculated, and the calculation shows that they are hardly affected by the TBF effect at the saturation density. At a high density two times greater than the saturation density, inclusion of the TBF may lead to a visible effect on the spectral function and may enhance the depletion of the hole states.
118833038
Transport parameters in neutron stars from in-medium NN cross sections
We present a numerical study of shear viscosity and thermal conductivity of symmetric nuclear matter, pure neutron matter, and beta-stable nuclear matter, in the framework of the Brueckner theory. The calculation of in-medium cross sections and nucleon effective masses is performed with a consistent two- and three-body interaction. The investigation covers a wide baryon density range as needed in the applications to neutron stars. The results for the transport coefficients in beta-stable nuclear matter are used to make preliminary predictions on the damping time scales of nonradial modes in neutron stars.
118506081
Three-body force effect on the properties of nuclear matter under the gap and continuous choices within the BHF approach
We have calculated and compared the three-body force effects on the properties of nuclear matter under the gap and continuous choices for the self-consistent auxiliary potential within the Brueckner-Hartree-Fock approach by adopting the Argonne V-18 and the Bonn B two-body potentials plus a microscopic three-body force (TBF). The TBF provides a strong repulsive effect on the equation of state of nuclear matter at high densities for both the gap and continuous choices. The saturation point turns out to be much closer to the empirical value when the continuous choice is adopted. In addition, the dependence of the calculated symmetry energy upon the choice of the self-consistent auxiliary potential is discussed.
15459179
Probing the isospin dependent in-medium nucleon–nucleon cross section by nucleon emissions
The effects of the symmetry potential and the isospin dependent in-medium nucleon-nucleon (NN) cross section on the number of proton(neutron) emissions N-p(N-n) are studied respectively within an isospin-dependent quantum molecular dynamics (IQMD) model. The isospin dependent in-medium NN cross section is found to have a strong influence on Np (Nn) but Np(Nn) is not sensitive to the symmetry potential for the neutron-deficient colliding system at relatively high energies. We propose to make use of the N-p(N-n) as a probe to extract information on the isospin dependent in-medium NN cross section. (C) 2002 Elsevier Science B.V. All rights reserved.
121866251
Rescaling for Kaon Structure Function
We use the valon model to analyse the dynamical rescaling of x in the inelastic structure functions and point out that the rescaling is just the delta approximation of the valon distribution functions. We apply the contribution of valence quarks to the mass of a hadron bound state to determine a few parameters for the x-rescaling and thus obtain the Kaon structure functions. The result is in good agreement with experimental data.
14014748
The reliability of pQCD approach in pion electromagnetic form factor
The pion electromagnetic form factor with leading and next-to-leading twist corrections are studied in the framework of pQCD approach. We find that, at small momentum transfer regions, Sudakov effects cannot provide a strong enough suppression of the non-perturbative contributions coming from large transverse separations, but at large momentum transfer region, non-perturbative contributions can be effectively suppressed. So pQCD approach can be applied at large momentum transfer region. At the energy region where experiment can access so far, i.e. Q < 4GeV, pQCD prediction can not be precise because there may be a quite large part of contributions coming from non-perturbative region. The calculation of power corrections may not be performed systematically in pQCD framework.
122365434
Bag skin effect for Friedberg-Lee model
Importance of the bag skin effect to determine the parameters of the Friedberg-Lee model is pointed out. The European Muon Collaboration (EMC) effect regarded as a bag skin effect can be used to determine the parameters of this model.
118982861
Sudakov form factor in effective field theory
We discuss the Sudakov form factor in the framework of the soft-collinear effective theory. The running of the short distance coefficient function from high to low scale gives the summation of Sudakov logarithms to all orders. Our discussions concentrate on the factorization and derivation of the renormalization group equation from the effective theory point of view. The intuitive interpretation of the renormalization group method is discussed. We compared our method with other resummation approaches in the literatures.
119499375
Productions of K*0(1430) and K(1) in B decays
We study the productions of p-wave mesons $K^*_{0}(1430)$, $K_{1}(1270)$ and $K_{1}(1400)$ in B decays. By the generalized factorization approach, we find that the branching ratios of $B\to K^*_{0}(1430) \phi$ are similar to those of $B\to K \phi$ while the branching ratios of $B\to K_{1}(1270) \phi$ and $B\to K_{1}(1400) \phi$ are $O(10^{-5})$ and $O(10^{-6})$, respectively. In terms of the observation of $B\to K_{1}(1270) \gamma$ by BELLE, we can remove the sign ambiguity in the mixing angle for physical states $K_1(1270)$ and $K_{1}(1400)$. In addition, we analyze annihilation contributions in the decays $B\to K_1 \phi$ and we conclude that they could be neglected.