Bulletin of the American Physical Society
2015 Fall Meeting of the APS Division of Nuclear Physics
Volume 60, Number 13
Wednesday–Saturday, October 28–31, 2015; Santa Fe, New Mexico
Session NC: Theoretical Modeling of Nuclei |
Hide Abstracts |
Chair: Richard Furnstahl, Ohio State University Room: Sweeney Ballroom B |
Saturday, October 31, 2015 8:30AM - 8:42AM |
NC.00001: Nuclear Physics from Lattice QCD Silas Beane Over the last several decades, theoretical nuclear physics has been evolving from a very-successful phenomenology of the properties of nuclei, to a first-principles derivation of the properties of the visible matter in the Universe from the known underlying theories of Quantum Chromodynamics (QCD) and Electrodynamics. These developments are being achieved using lattice QCD, a method for treating QCD numerically with large computers. After a brief motivational introduction, I will present some of the recent calculations of the properties of the simplest nuclear and hypernuclear systems using lattice QCD. [Preview Abstract] |
Saturday, October 31, 2015 8:42AM - 8:54AM |
NC.00002: The Effects of Regulators on NN and 3N forces in Chiral Effective Field Theory Alex Dyhdalo, Richard Furnstahl, Kai Hebeler, Ingo Tews For potentials derived using Chiral Effective Field Theory, it is necessary to choose a regulator and cutoff scale for the theory. Under Weinberg's power counting prescription, the perturbatively derived potential is iterated to all orders, leading to artifacts (e.g., residual cutoff dependence) from the regulator. We investigate different choices of regulators and their associated artifacts in the uniform system at finite density for two- and three-body forces. We find significant effects from different regulator choices at Hartree-Fock and 2nd order in the perturbative many-body energy expansion. The potential implications of regulator and scale choice on the theory's power counting is discussed. [Preview Abstract] |
Saturday, October 31, 2015 8:54AM - 9:06AM |
NC.00003: \textit{Ab initio} no core configuration interaction calculations in the natural orbital basis Chrysovalantis Constantinou, Mark A. Caprio, James P. Vary, Pieter Maris The natural orbital basis has been successfully used in the past in atomic and molecular structure calculations. The natural orbitals used in those calculations are calculated by diagonalizing the electron one-body density matrix. Here we develop natural orbitals for nuclear no-core configuration interaction (NCCI) calculations. A NCCI calculation using an initial single particle basis, such as the harmonic oscillator basis, must first be performed in order to obtain a one-body density matrix. The eigenvectors of the one-body density matrix are the natural orbitals, and the corresponding eigenvalues are the occupations of these natural orbitals in the nuclear wave function. According to these occupancies, the most important natural orbitals, in the sense of the most occupied, can then be selected and used in a NCCI calculation. We discuss \textit{ab initio} nuclear NCCI calculations for light nuclei and assess their ability to provide faster convergence. [Preview Abstract] |
Saturday, October 31, 2015 9:06AM - 9:18AM |
NC.00004: Yang-Mills equation for the collective model Nick Sparks, george rosensteel To determine the collective model connection, an equation is needed that relates the connection to the nuclear current. The correct equation is the Yang-Mills equation for the collective model bundle. The essential mathematical structure of both Yang-Mills and the collective model is a bundle with a differential geometric connection, but the particulars are quite different. In particular, the base manifold for Yang-Mills is Minkowski space, whereas the base manifold for the collective model is the space of all nuclear orientations and quadrupole deformations. The Lie structure groups are both non-abelian: Yang-Mills electroweak is U(2) and the collective model is SO(3). The YM equation is derived from the YM Lagrangian which depends on the bundle curvature. Solutions are found for rotation about one principal axis. These solutions range continuously from the irrotational flow to the rigid body connections as the current ranges from irrotational to rigid. [Preview Abstract] |
Saturday, October 31, 2015 9:18AM - 9:30AM |
NC.00005: Kinetic energy for the nuclear Yang-Mills collective model George Rosensteel, Nick Sparks The Bohr-Mottelson-Frankfurt model of nuclear rotations and quadrupole vibrations is a foundational model in nuclear structure physics. The model, also called the geometrical collective model or simply GCM, has two hidden mathematical structures, one Lie group theoretic and the other differential geometric. Although the group structure has been understood for some time, the geometric structure is a new unexplored feature that shares the same mathematical origin as Yang-Mills, viz., a vector bundle with a non-abelian structure group and a connection. Using the de Rham Laplacian $\triangle = \star d \star d$ from differential geometry for the kinetic energy extends significantly the physical scope of the GCM model. This Laplacian contains a ``magnetic" term due to the coupling between base manifold rotational and fiber vorticity degrees of freedom. When the connection specializes to irrotational flow, the Laplacian reduces to the Bohr-Mottelson kinetic energy operator. More generally, the connection yields a moment of inertia that is intermediate between the extremes of irrotational flow and rigid body motion. [Preview Abstract] |
Saturday, October 31, 2015 9:30AM - 9:42AM |
NC.00006: Strength function sum rules and the generalized Brink-Axel hypothesis Calvin W. Johnson Sum rules provide useful insights into transition strength functions and are often expressed as expectation values of an operator. I will show that non-energy-weighted transition sum rules have strong secular dependences on the energy of the initial state. Such non-trivial systematics have consequences: the simplification suggested by the generalized Brink-Axel hypothesis, for example, does not hold for most cases, though it weakly holds for electric dipole transitions. Furthermore, I show the systematics can be understood through spectral distribution theory, calculated via traces of operators and of products of operators; seen through this lens, violation of the generalized Brink-Axel hypothesis is unsurprising. [Preview Abstract] |
Saturday, October 31, 2015 9:42AM - 9:54AM |
NC.00007: Survey of Reflection-Asymmetric Nuclear Deformations Erik Olsen, Noah Birge, Jochen Erler, Witek Nazarewicz, Alex Perhac, Nicolas Schunck, Mario Stoitsov Due to spontaneous symmetry breaking it is possible for a nucleus to have a deformed shape in its ground state. It is theorized that atoms whose nuclei have reflection-asymmetric or pear-like deformations could have non-zero electric dipole moments (EDMs). Such a trait would be evidence of CP-violation, a feature that goes beyond the Standard Model of Physics. It is the purpose of this project to predict which nuclei exhibit a reflection-asymmetric deformation and which of those would be the best candidates for an EDM measuring experiment. Using nuclear Density Functional Theory along with the new computer code AxialHFB and massively parallel computing we calculated ground state nuclear properties for thousands of even-even nuclei across the nuclear chart: from light to superheavy and from stable to short-lived systems. Six different Energy Density Functionals (EDFs) were used to assess systematic errors in our calculations. Overall, 140 even-even nuclei (near and among the lantanides and actinides and in the superheavy region near N=184) were predicted by all 6 EDFs to have a pear-like deformation. The case of $^{112}$Xe also proved curious as it was predicted by 5 EDFs to have a pear-like deformation despite its proximity to the two-proton drip line. [Preview Abstract] |
Saturday, October 31, 2015 9:54AM - 10:06AM |
NC.00008: \emph{Ab initio} multi-irrep symplectic no-core configuration interaction calculations A.E. McCoy, M.A. Caprio, T. Dytrych The $\mathrm{Sp}(3,R)$ symplectic symmetry has a close physical connection to both the microscopic shell model and the collective deformation and rotational degrees of freedom. In addition, recent SU(3)-coupled no-core shell model [SU(3)-NCSM] calculations indicate that rotational nuclei have an approximate symplectic symmetry. \emph{Ab Initio} multi-irrep symplectic no-core configuration interaction (NCCI) calculations combine the traditional symplectic model with the SU(3)-NCSM to extend the range of NCCI calculations beyond the $p$-shell nuclei. Moreover, carrying out calculations in a symplectic basis provides a natural framework in which to study the emerging rotational behavior observed in NCCI calculations. We present key elements of this framework and initial calculations. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700