Bulletin of the American Physical Society
3rd Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 54, Number 10
Tuesday–Saturday, October 13–17, 2009; Waikoloa, Hawaii
Session DM: Nuclear Theory II |
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Chair: Francesca Sammarruca, University of Idaho Room: Kings 1 |
Thursday, October 15, 2009 7:00PM - 7:15PM |
DM.00001: Effective theory for two fermions in a trap Ionel Stetcu, Jimmy Rotureau, Bruce Barrett, Bira van kolck Systems with large scattering length $a_2$ are of particular interest since they exhibit universal properties when particle momenta are small compared to $1/r_0$ with r0 being the range of the interaction. This situation occurs for instance, in nuclear physics where the two-nucleon system has two S-wave channels where $a_2 >>r_0$. We have applied the general principles of Effective Field Theory for the description of two fermions in a harmonic oscillator trap. Our formalism is based on a controlled expansion of the interaction between the two fermions as a series of contact interactions with an increasing number of derivatives. Corrections to the interaction beyond leading order are treated in perturbation theory. Results for the energies of the two-fermion system for different values of $a_2/b$ ($b$ being the trap length) and $r_0/b$ will presented. [Preview Abstract] |
Thursday, October 15, 2009 7:15PM - 7:30PM |
DM.00002: Effective theory for trapped few-fermion systems Jimmy Rotureau, Ionel Stetcu, Bruce Barrett, Mike Birse, Bira Van Kolck The properties of strongly interacting Fermi gases have been the object of great interest in recent years. When the scattering length $a_2$ is much larger than the effective range of the interaction $r_0$, few-atom systems serve as a testing ground for techniques developed for the ab-initio solution of few-nucleon systems. We have applied the principles of Effective Field Theory to describe few-fermions systems in a harmonic trap. The interaction is written as a controllable expansion of contact interactions with derivatives. The no-core shell model is used to solve the many-body Schr\"odinger equation at leading order and corrections beyond LO are treated in perturbation theory. We have also adressed the relationship between the two-body and many-body cutoffs needed for a consistent model space. Results for the energies of the 3-fermions system at unitarity will be presented and shown to agree with known results. Results for systems with 3, 4 fermions for different values of $a_{2}/b$ (b being the trap length) and $r_{0}/b$ will also be presented. [Preview Abstract] |
Thursday, October 15, 2009 7:30PM - 7:45PM |
DM.00003: Ab initio no core results for light nuclei with realistic basis functions James Vary, Alina Negoita, Pieter Maris, Andrey Shirokov We perform no-core (NCFC) calculations for a set of light nuclei with realistic NN interactions. We perform our calculations both in a harmonic oscillator and Woods-Saxon basis and compare convergence rates for the ground state energies, energies of selected excited states, rms radii and other observables. The results for rms radii of light and weakly bound nuclei present useful tests of more realistic basis spaces such as the Woods-Saxon basis. We will discuss factorization of the center-of-mass motion and show how insuring factorization affects the results in the Woods-Saxon basis spaces. [Preview Abstract] |
Thursday, October 15, 2009 7:45PM - 8:00PM |
DM.00004: {\it Ab initio} no-core full configuration calculation of light nuclei by Monte Carlo shell model with JISP16 $NN$ interaction T. Abe, P. Maris, T. Otsuka, N. Shimizu, Y. Utsuno, J.P. Vary Benchmark test calculation of ground-state properties of light nuclei in no-core full configuration approach is presented. Monte Carlo shell model calculation by a stochastic diagonalization technique is compared with that in a exact diagonalization using the J-matrix inverse scattering potential (JISP16). [Preview Abstract] |
Thursday, October 15, 2009 8:00PM - 8:15PM |
DM.00005: Toward the first ab initio description of the deuterium-tritium fusion Sofia Quaglioni, Petr Navratil We are building a new capability to describe light-ion fusion reactions from first principles, known as \textit{ab initio} NCSM/RGM approach [1,2]. Using a recently developed formalism based on nucleon-nucleus basis states, we have completed a promising preliminary study of nucleon-nucleus scattering, particularly $n-^{4}$He scattering below the $d+^{3}$H threshold [1,2]. Now we are developing the deuterium-nucleus formalism that coupled with the nucleon-nucleus basis will allow us the first \textit{ab initio} calculation of the $^{3}$H($d$,$n)^{4}$He fusion. We present recent results and work in progress. \\[4pt] [1] S. Quaglioni and P. Navratil, Phys. Rev. Lett. \textbf{101}, 092501 (2008). \\[0pt] [2] S. Quaglioni and P. Navratil, Phys. Rev. C \textbf{79}, 044606 (2009). [Preview Abstract] |
Thursday, October 15, 2009 8:15PM - 8:30PM |
DM.00006: Density Functional Theory for non-relativistic Fermions in the Unitarity Limit Gautam Rupak, Thomas Schaefer We derive an energy density functional for non-relativistic spin one-half fermions in the limit of a divergent two-body scattering length. Using an epsilon expansion around $d=4-\epsilon$ spatial dimensions we compute the coefficient of the leading correction beyond the local density approximation (LDA). In the case of $N$ fermionic atoms trapped in a harmonic potential this correction has the form $E=E_{LDA}[ 1 + c_s (3N)^{-2/3} ]$, where $E_{LDA}$ is the total energy in LDA approximation. At next-to-leading order in the $\epsilon$-expansion we find $c_s=1.68$, which is significantly larger than the result for non-interacting fermions, $c_s=0.5$. [Preview Abstract] |
Thursday, October 15, 2009 8:30PM - 8:45PM |
DM.00007: 3D Time-Dependent Density Functional Theory for Superfluid Nuclear Systems Aurel Bulgac, Piotr Magierski, Kenneth Roche, Ionel Stetcu We have recently formulated a full 3D Time-Dependent version of the Density Functional Theory for superfluid nuclear systems and implemented it as a highly efficient parallelized code on leadership class supercomputers, and we refer to it as the Time-Dependent Superfluid Local Density Approximation (TD-SLDA). TD-SLDA can be used in particular to calculate the linear response to an arbitrary external probe of any nucleus, without any symmetry restrictions and in a fully selfconsistent manner and with a correct treatment of all spurious modes. As one of the first applications of TD-SLDA we study the response of a nucleus to a Coulomb field generated by a relativistic projectile. [Preview Abstract] |
Thursday, October 15, 2009 8:45PM - 9:00PM |
DM.00008: Non-empirical pairing functional from low-momentum two- and three-body interactions Thomas Lesinski, Thomas Duguet, Kai Hebeler, Achim Schwenk We present systematic calculations of pairing gaps in semi-magic nuclei across the nuclear chart using the Energy Density Functional method. A non-empirical pairing functional is derived at lowest order in the low-momentum, vacuum two-nucleon interaction, including the Coulomb force, and chiral three-nucleon interaction. The particle-hole part of the functional is built to reproduce the Hartree-Fock level density obtained with the same interaction. Energies of odd nuclei are calculated self-consistently in the equal-filling approximation, which allows a direct comparison to odd-even mass difference data. We assess the relative contributions of two-body and three-body direct terms, blocking, and missing higher-order terms of the perturbative expansion to pairing in finite nuclei. [Preview Abstract] |
Thursday, October 15, 2009 9:00PM - 9:15PM |
DM.00009: ABSTRACT WITHDRAWN |
Thursday, October 15, 2009 9:15PM - 9:30PM |
DM.00010: Helium Halo Nuclei from Low-Momentum Interactions Sonia Bacca The physics of the strong force gives rise to fascinating halo structures in light nuclei. A prominent example are the helium halo nuclei, He6 and He8, with a two- and a four-neutrons halo, respectively. In literature, several ab initio calculations of these nuclei are found, which are based on traditional potentials and include short-range phenomenology. Our goal is to describe properties of halo nuclei starting from forces derived within the modern approach of effective field theory, where two- and three-body forces among nucleons arise naturally and consistently with each other. Along the road to accomplish that, we present our theoretical approach to the study of He6 and He8 with low momentum interactions. Binding energies and radii will be discussed and compared to experimental data. [Preview Abstract] |
Thursday, October 15, 2009 9:30PM - 9:45PM |
DM.00011: Large-Scale Calculations of Single-Particle Properties Carlo Barbieri We review recent large-scale calculations of single-particle energies and spectroscopic factors around closed shell nuclei in the {\em sd} and {\em pf} regions. Emphasis will be put on the following results: \begin{itemize} \item The self-consistent Green's functions method employed in the calculations reproduces the benchmark results for the binding energy of $^{4}$He with good accuracy. Ab-initio calculations have now been performed up to $^{56}$Ni. \item Preliminary studies of spectroscopic factors, based on the chiral N3LO force, exhibit an asymmetry dependence similar to that observed in heavy-ion knockout experiments but weaker in magnitude. \end{itemize} [Preview Abstract] |
Thursday, October 15, 2009 9:45PM - 10:00PM |
DM.00012: The Importance of Concavity for Nuclear BEs and Thermodynamical Functions Bruce Barrett, Bertrand Giraud, Byron Jennings, Nicholas Toberg The role of concavity of nuclear energy chains or surfaces in determining the BEs of unknown nuclides by extra- and/or interpolation will be presented. Studies of the concavity of nuclear thermodynamical functions allows the determination of the average value of H and the free energy as functions of the average value of A for finite temperature. These two quantities allow error bars to be set on the BEs predicted previously. The consequences of the concavity of H on the nuclear density functional will also be discussed. [Preview Abstract] |
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