Bulletin of the American Physical Society
2005 2nd Joint Meeting of the Nuclear Physics Divisions of the APS and The Physical Society of Japan
Sunday–Thursday, September 18–22, 2005; Maui, Hawaii
Session JK: Nuclear Theory II |
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Sponsoring Units: DNP JPS Chair: Wayne Polyzou, University of Iowa Room: Ritz-Carlton Hotel Maui |
Thursday, September 22, 2005 9:00AM - 9:15AM |
JK.00001: Pion Condensation with Parity and Charge Projection in Relativistic Mean Field Model for Finite Nuclei Hiroshi Toki, Yoko Ogawa, Satoru Sugimoto, Kiyomi Ikeda We study the role of pion on nuclear structure in the relativistic mean field model with projection of parity and charge before variation. We find that the effect of the projection of parity and charge is extremely large for the case of pion condensation, which makes violation of parity and charge number causing particle jump of major shells. [Y. Ogawa et al., Prog. Theor. Phys. 111, 75 (2004)] The energy gain due to the pion becomes the major source of binding for not only jj-closed shell nuclei but also LS-closed shell nuclei due to the projection. The pion contributes also to the spin-orbit splitting of finite nuclei, which are the foundation of nuclear shell structure. We calculate N=Z nuclei using the chiral sigma model Lagrangian. We find the reduction of sigma mean field by about 20{\%}, which corresponds to the recovery of nuclear chiral condensate by 20{\%}. About a half of the spin-orbit splitting comes from sigma and omega and the other half from pion. [Preview Abstract] |
Thursday, September 22, 2005 9:15AM - 9:30AM |
JK.00002: A practical method to solve the cut-off Coulomb problem in the Lippmann-Schwinger RGM formalism Y. Fujiwara In the momentum representation, incorporating the long-range Coulomb force always poses problems. We propose a simple and accurate method to solve the Lippmann-Schwinger RGM (resonating-group method) equations, with the Coulomb force included at the constituent level. If the cut-off Coulomb force is used, the direct and exchange Coulomb kernels are explicitly evaluated with a reasonable size for the cut-off radius $R$, without spoiling the effect of the Pauli principle. The direct potential thus obtained becomes a screening Coulomb in the error function form. The cut-off is no longer sharp, but the standard procedure of the cut-off Coulomb problem, proposed by Vincent and Phatak [Phys. Rev. C10, 391 (1974)], can still be used by solving the asymptotic waves down to $R_{\rm in} \ll R$, where the full Coulomb force is acting. We show two examples, $\alpha \alpha$ RGM and the charged cases of the quark-model baryon-baryon interactions fss2. In the latter case, accurate determination of the nuclear phase shifts is very important for evaluating the low-energy parameters, including the inelastic capture ratio at rest for $\Sigma^- p$ scattering. [Preview Abstract] |
Thursday, September 22, 2005 9:30AM - 9:45AM |
JK.00003: Proton Elastic Scattering from $^{60-74}$Ca Nuclei Kaori Kaki Recent relativistic-mean-field calculations have provided nuclear distributions of Ca isotopes whose mass numbers are 60 through 74. We calculate observables of proton elastic scattering from these unstable nuclei, and plan to show some relations between observables and much more spreading neutron distributions than proton ones. The calculations are based on relativistic impulse approximation (RIA) and the incident energies of proton are chosen 300 and 400 MeV. In these energies predictions of RIA have been known to provide good agreements with experimental data for many kinds of nuclei. [Preview Abstract] |
Thursday, September 22, 2005 9:45AM - 10:00AM |
JK.00004: Vlasov Equation for Quantized Meson Fields Mamoru Matsuo, Tetsuo Matsui In order to describe the final stage of space-time evolution of dense matter created by ultrarelativistic nuclear collisions, we formulate a kinetic theory of mesons starting from the Heisenberg equation of motion of self-interacting quantized fields. As a dense hadronic matter formed by ultrarelativistic nuclear collision is diluted by the expansion, one expects that the system undergoes a phase transition associated with the spontaneous breakdown of the chiral symmetry which is restored temporally after the collision by the formation of a quark-gluon plasma. As the quark-gluon plasma hadronizes and turns into the confining phase, the system would expand under the influence of the growing chiral condensate. This physical situation is very similar to what happens when some of the magnetically trapped atoms condense into the lowest single particle level forming a Bose-Einstein condensate. The dynamics of such a system is described by the coupled equations of motion in the form of the Boltzmann-Vlasov equations. We will show that a similar set of equations can be derived for a system of interacting mesons described by the relativistic quantum field theory and discuss on the dispersion relations of the collective mesonic excitations at finite temperatures using these kinetic equations. [Preview Abstract] |
Thursday, September 22, 2005 10:00AM - 10:15AM |
JK.00005: 3-D Unrestricted TDHF - Studies with full Skyrme interaction Sait Umar, Volker Oberacker We present time-dependent Hartree-Fock (TDHF) studies without any spatial symmetry restrictions as well as no time-reversal invariance for the Skyrme force. The code uses the basis-spline collocation method for lattice representation. We will discuss the general nature of these unrestricted calculations and in particular the effects of no time-reversal invariance. This introduces many additional terms into the Skyrme energy functional, including spin-currents and tensors. We study a number of systems to understand the effects of time-odd parts of the interaction on heavy-ion fusion using some of the more recent parameterizations of the Skyrme force. The results of applying this code to study heavy-ion fusion for deformed nuclei will be discussed in another talk. Ref: A.S. Umar and V.E. Oberacker, Eur. Phys. J. A {\bf24} (2005). [Preview Abstract] |
Thursday, September 22, 2005 10:15AM - 10:30AM |
JK.00006: TDHF fusion studies including dynamic alignment due to Coulomb excitation Volker Oberacker, Sait Umar We utilize the Time-Dependent Hartree-Fock (TDHF) method to calculate heavy-ion fusion cross sections for systems involving a spherical projectile and a deformed target nucleus. The calculations involve modern Skyrme forces and are carried out on a large 3-D Cartesian lattice using the Basis-Spline collocation method. The computations involve two separate steps: first, a TDHF calculation for a given initial orientation of the deformed nucleus, and secondly a semiclassical time-dependent Coulomb excitation calculation to determine the relative orientation probability of the deformed nucleus near the distance of closest approach. In this paper, we focus on the second aspect of the theory. Specific results will be presented for the light system ($^{16}O+^{22}Ne$) and for the heavy system $^{64}Ni+^{162}Dy$. We demonstrate that in heavier systems the alignment due to multiple E2 and E4 Coulomb excitation is substantial and must be taken into account when calculating the fusion cross section with TDHF. Ref: A.S. Umar and V.E. Oberacker, Eur. Phys. J. A {\bf24} (2005) [Preview Abstract] |
Thursday, September 22, 2005 10:30AM - 10:45AM |
JK.00007: Application of the coherent state formalism to multiply excited states M.A. Caprio Results are obtained allowing the coherent state formalism for algebraic models to be applied to states possessing an arbitrarily large number of intrinsic excitation quanta. A general procedure is presented for evaluation of the matrix element of an arbitrary $n$-body operator between coherent states constructed from multiple orthogonal coherent boson creation operators. The results may be applied to a variety of algebraic models. Supported by the US DOE under grant DE-FG02-91ER-40608. [Preview Abstract] |
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