Bulletin of the American Physical Society
2017 Fall Meeting of the APS Division of Nuclear Physics
Volume 62, Number 11
Wednesday–Saturday, October 25–28, 2017; Pittsburgh, Pennsylvania
Session NF: Nuclear Theory II |
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Chair: Pieter Maris, Iowa State University Room: Salon 6 |
Saturday, October 28, 2017 8:30AM - 8:42AM |
NF.00001: Updates on the Application of the Density Matrix Expansion to Nuclei Alexander Dyhdalo, Scott Bogner, Richard Furnstahl The density matrix expansion (DME) is a method to produce purely local energy density functionals for finite-range potentials. We have applied a regulator-based coordinate-space approach to the DME for NN and 3N forces derived from chiral effective field theory both with and without Deltas, Phys. Rev. C 95, 054314 (2017). We also give updates on the status of the functional implementation of the derived density-dependent couplings, led by R. Navarro Perez and N. Schunck at LLNL, and discuss possible future directions. [Preview Abstract] |
Saturday, October 28, 2017 8:42AM - 8:54AM |
NF.00002: Pairing properties from random distribution of single-particle energy levels Md Abdullah Al Mamun, Madappa Prakash Exploiting the similarity between the bunched single-particle (sp) energy levels of nuclei and of random distributions around the Fermi surface, pairing properties of the latter are calculated to establish statistically-based bounds on the basic characteristics of the pairing phenomenon. While the ratio of the critical temperature $T_c$ to the zero-temperature pairing gap is close to its BCS Fermi gas value, the ratio of the superfluid to the normal phase specific heats at $T_c$ differs significantly from its Fermi gas counterpart. The scatter around the mean value for the discontinuity in the specific heat at $T_c$ is largest when a couple of sp levels lie closely on either side of the Fermi surface, but other levels are far away from it. To the extent that the sp levels of the random spacing model resemble those of nuclei which exhibit considerable dependence on choices of the energy density functionals and pairing schemes used, our results indicate the variation to be expected in the basic characteristics of the pairing phenomenon in nuclei.These results can help to promote further nuclear level density measurements to pin down the critical temperature for the pairing phase transition of nucleons in nuclei, and to perform sensitivity tests in astrophysical setting. [Preview Abstract] |
Saturday, October 28, 2017 8:54AM - 9:06AM |
NF.00003: Binding energies and energy differences for \(p\)-shell nuclei from \textit{ab initio} calculations with natural orbitals Patrick J. Fasano, Mark A. Caprio, Chrysovalantis Constantinou, Pieter Maris, James P. Vary \textit{Ab initio} methods in nuclear theory strive to make quantitative predictions of nuclear observables, starting with the internucleon interaction. In the no-core configuration interaction (NCCI) approach, the nuclear many-body problem is solved in a basis of Slater determinants constructed from single-particle states. NCCI calculations are computationally limited by combinatorial explosion of the many-body basis size; as such, choice of basis greatly influences convergence. Natural orbitals, constructed by diagonalizing the one-body density matrix from an initial many-body calculation, maximize occupation of the lowest single-particle states and thereby reduce the importance of higher-lying many-body basis states. We use natural orbitals to explore energies and energy differences in \(p\)-shell nuclei. [Preview Abstract] |
Saturday, October 28, 2017 9:06AM - 9:18AM |
NF.00004: Cluster orbitals for the mirror nuclei \boldmath{$^7\mathrm{Li}$} and \boldmath{$^7\mathrm{Be}$} Chrysovalantis Constantinou, Mark A. Caprio, Patrick J. Fasano Certain light nuclei are dominated by alpha particle clustering. In these nuclei, the alpha clusters form a molecular like structure and any additional nucleon(s) are orbiting in the potential created by the alpha clusters. The mirror nuclei $^7\mathrm{Li}$ and $^7\mathrm{Be}$ can be viewed as a $^8\mathrm{Be}$ core plus a proton or neutron hole, respectively. We derive the single-particle orbitals for $^7\mathrm{Li}$ and $^7\mathrm{Be}$ by solving the single-particle Schr\"{o}dinger equation for a proton (neutron) hole in the potential created by the $^8\mathrm{Be}$ core. Specifically, we derive the energies of the ground and excited states, the radii, and electromagnetic transition probabilities. We also compare the calculated observables against \textit{ab initio} no-core configuration interaction calculations using realistic interactions. [Preview Abstract] |
Saturday, October 28, 2017 9:18AM - 9:30AM |
NF.00005: Exploring nuclear optical potentials under similarity renormalization group transformations R. P. Caulfield, R. J. Furnstahl Recent work has suggested that incorporating nonlocality in (d,p) scattering introduces sensitivity to high n-p momenta and the deuteron D-state probability [1,2]. This leads to the question of how similarity renormalization group transformations, which soften potentials and increase nonlocality, impact optical potentials. We explore this question using simple models. \\ \relax [1] G.~W.~Bailey, N.~K.~Timofeyuk and J.~A.~Tostevin, %``Sensitivity of ( d , p ) Reactions to High n-p Momenta and the Consequences for Nuclear Spectroscopy Studies,'' Phys.\ Rev.\ Lett.\ {\bf 117}, 162502 (2016) %doi:10.1103/PhysRevLett.117.162502 [arXiv:1609.07303]. \\ \relax [2] G.~W.~Bailey, N.~K.~Timofeyuk and J.~A.~Tostevin, %``Nonlocal nucleon-nucleus interactions in (d,p) reactions: Role of the deuteron D-state,'' Phys.\ Rev.\ C {\bf 95}, 024603 (2017) %doi:10.1103/PhysRevC.95.024603 [arXiv:1701.05853]. [Preview Abstract] |
Saturday, October 28, 2017 9:30AM - 9:42AM |
NF.00006: Symplectic no-core configuration interaction framework for \textit{ab initio} nuclear structure. I. Convergence behavior in $p$-shell nuclei Anna E McCoy, Mark A Caprio, Tomas Dytrych A major challenge in quantitatively predicting nuclear structure \emph{ab initio}, directly from realistic nucleon-nucleon interactions, arises due to an explosion in the dimension of the traditional configuration interaction basis as the number of nucleons and included shells increases. The need for including highly excited configurations exists, in large part, because the kinetic energy induces strong coupling across shells. However, the kinetic energy conserves symplectic symmetry. Combining symplectic symmetry with the no-core configuration interaction (NCCI) framework provides a means of identifying and restricting the basis to include only the highly excited configurations which dominantly contribute to the nuclear wavefunction, thereby reducing the size of basis necessary to obtain accurate results. We present a framework for \emph{ab initio} symplectic no-core configuration interaction (SpNCCI) calculations of the nuclear problem and explore convergence behavior of calculations of $p$-shell nuclei in this framework. [Preview Abstract] |
Saturday, October 28, 2017 9:42AM - 9:54AM |
NF.00007: Symplectic no-core configuration interaction framework for \textit{ab initio} nuclear structure. II. Structure of rotational states Mark A. Caprio, Anna E. McCoy, Tomas Dytrych Rotational band structure is readily apparent as an emergent phenomenon in \textit{ab initio} nuclear many-body calculations of light nuclei, despite the incompletely converged nature of most such calculations at present. Nuclear rotation in light nuclei can be analyzed in terms of approximate dynamical symmetries of the nuclear many-body problem: in particular, Elliott's $\mathrm{SU}(3)$ symmetry of the three-dimensional harmonic oscillator and the symplectic $\mathrm{Sp}(3,R)$ symmetry of three-dimensional phase space. Calculations for rotational band members in the \textit{ab initio} symplectic no-core configuration interaction (SpNCCI) framework allow us to directly examine the $\mathrm{SU}(3)$ and $\mathrm{Sp}(3,R)$ nature of rotational states. We present results for rotational bands in $p$-shell nuclei. [Preview Abstract] |
Saturday, October 28, 2017 9:54AM - 10:06AM |
NF.00008: Realistic calculations for $c$-coefficients of the isobaric mass multiplet equation in $1p0f$ shell nuclei Erich Ormand, Alex Brown, Morten Hjorth-Jensen We present calculations for the $c$-coefficients of the isobaric mass multiplet equation for nuclei from $A=42$ to $A=54$ based on two-body effective interactions derived from three realistic nucleon-nucleon interactions: CD-Bonn, N$^3$LO, and Argonne V18. The two-body effective interactions were derived using G-matrix or V$_{low~k}$ augmented by perturbation theory extended to third order. We demonstrate a clear dependence in the $c$-coefficients on the short-ranged charge-symmetry breaking (CSB) part of the strong interaction, which is required to reproduce their overall behavior as a function of excitation (angular momentum). We find, however, that the CSB component in all three realistic nucleon-nucleon interactions is too large when compared to experiment, and that, furthermore, there is significant disagreement between each of the three interactions. This implies either: 1) a deficiency in our understanding of isospin-symmetry breaking in the nucleon-nucleon interaction, 2) significant isospin-symmetry breaking in the initial three-nucleon interaction, or 3) large contributions to isospin-symmetry breaking in three-nucleon interactions induced by the renormalization procedure. [Preview Abstract] |
Saturday, October 28, 2017 10:06AM - 10:18AM |
NF.00009: Moving Towards a State of the Art Charge-Exchange Reaction Code Terri Poxon-Pearson, Filomena Nunes, Gregory Potel Charge-exchange reactions have a wide range of applications, including late stellar evolution, constraining the matrix elements for neutrinoless double \(\beta\)-decay, and exploring symmetry energy and other aspects of exotic nuclear matter [1,2]. Still, much of the reaction theory needed to describe these transitions is underdeveloped and relies on assumptions and simplifications that are often extended outside of their region of validity [3]. In this work, we have begun to move towards a state of the art charge-exchange reaction code. As a first step, we focus on Fermi transitions using a Lane potential in a few body, Distorted Wave Born Approximation (DWBA) framework. We have focused on maintaining a modular structure for the code so we can later incorporate complications such as nonlocality, breakup, and microscopic inputs. Results using this new charge-exchange code will be shown compared to the analysis in [2] for the case of 48Ca(p,n)48Sc. [1] R. G. T. Zegers et at., Phys. Rev. Lett. 99 (2007) 202501. [2] Danielewicz et al., Nucl. Phys. 958 (2017) 147. [3] T.N. Taddeucci et al., Ncl. Phys. A469, 125 (1987). [Preview Abstract] |
Saturday, October 28, 2017 10:18AM - 10:30AM |
NF.00010: Hybrid Neutrosophic Triplet Field of Type 2 Florentin Smarandache, Mumtaz Ali A Hybrid Neutrosophic Triplet Field of Type 2 (HNTF2) is a set F endowed with two laws * and {\#} such that: \newline 1: (F, *) is a classical commutative group; \newline 2: (F, {\#}) is a neutrosophic triplet group; \newline 3: The law {\#} is distributive over the law *. \newline Applications of HNTF2 in physics are investigated. [Preview Abstract] |
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