Bulletin of the American Physical Society
2021 Fall Meeting of the APS Division of Nuclear Physics
Volume 66, Number 8
Monday–Thursday, October 11–14, 2021; Virtual; Eastern Daylight Time
Session KM: Nuclear Theory V |
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Chair: Andrew Jackura, ODU Room: White Hill |
Wednesday, October 13, 2021 11:30AM - 11:42AM |
KM.00001: Ab initio elastic scattering with chiral NN forces up to NNLO (II): n+12C Charlotte Elster, Robert B Baker, P. Maris, S. P Weppner, M. Burrows, Kristina D Launey, Gabriela Popa Effective interactions derived from first principles used to describe elastic scattering of nucleons from nuclei can be formulated consistently within a multiple scattering theory based on the spectator expansion. In its leading order the NN force enters into the description of the nucleus as well as the reaction itself and is treated on the same footing in both. Employing a semilocal coordinate-space regularized chiral EFT NN force and corresponding one-body density matrix elements from the LENPIC collaboration, we study the truncation errors of the chiral expansion considering the neutron differential cross section in forward direction for elastic scattering from 12C for projectile energies between 100 and 150 MeV. We also show that for small scattering angles or small momentum transfer the n+12C differential cross section shows a strong correlation with the NN Wolfenstein amplitude A for the same momentum transfer. |
Wednesday, October 13, 2021 11:42AM - 11:54AM |
KM.00002: Ab initio elastic scattering with chiral NN forces up to NNLO (I): p+16O Robert B Baker, Charlotte Elster, Pieter Maris, S. P Weppner, Matthew B Burrows, Kristina D Launey, Gabriela Popa Effective interactions derived from first principles used to describe elastic scattering of nucleons from nuclei can be formulated consistently within a multiple scattering theory based on the spectator expansion. In its leading order the NN force enters into the description of the nucleus as well as the reaction itself and is treated on the same footing in both. Employing a semilocal coordinate-space regularized chiral EFT NN force and corresponding one-body density matrix elements from the LENPIC collaboration, we study the truncation errors of the chiral expansion for proton elastic scattering observables from 16O for projectile energies between 100 and 200 MeV. Using a Bayesian truncation error model developed by the BUQEYE collaboration, we quantify these errors in the NA system for the first time while examining the reaction cross section, differential cross section, and analyzing power for this reaction. |
Wednesday, October 13, 2021 11:54AM - 12:06PM |
KM.00003: Ab Initio Optical Potentials for Elastic Scattering at Low Energies Using the Symmetry-Adpated No-Core Shell Model Matthew B Burrows, Kristina D Launey, Robert B Baker, Grigor H Sargsyan, Tomas Dytrych, Jerry P Draayer Ab initio optical potentials for elastic scattering at low energy is of particular interest for experiments at rare isotope beam facilities. In this work we combine the ab initio symmetry-adapted no-core shell-model results [1,2] with the Green's function evaluation of the optical potential through a self-energy calculation [3,4]. Specifically, we show preliminary results for neutron elastic scattering off Helium-4 and Carbon-12 with projectile energies between 0.5 and 10 MeV. We also discuss the role of collectivity and present comparisons to earlier models. |
Wednesday, October 13, 2021 12:06PM - 12:18PM |
KM.00004: Statistical tools for a better optical model Manuel Catacora-Rios, Garrett B King, Amy E Lovell, Filomena Nunes In this work, we study three modern tools in the context of nuclear reactions with the goal of constraining the optical potential: i) the principal component analysis; ii) the sensitivity analysis based on derivates; and iii) the Bayesian evidence. We first apply these tools to a toy case, comparing the form of the assumed optical potential. Then we consider two different reaction observables, elastic angular distributions and polarization data for reactions on 48Ca and 208Pb each at two different beam energies. While our study with the principal component analysis did not offer insights, both the sensitivities and the Bayesian evidence prove to be useful in analyzing the optical model and associated data. We discuss the implications of our findings to the field. |
Wednesday, October 13, 2021 12:18PM - 12:30PM |
KM.00005: Exploring Applications and Properties of Microscopic Optical Potentials Taylor Whitehead, Jeremy W Holt, Filomena Nunes We test new applications of the recently constructed WLH microscopic global optical potential. The WLH global optical potential has been shown to be in reasonable agreement with experiment for elastic scattering cross sections involving a wide range of isotopes and scattering energies. However, we demonstrate that this is not sufficient for reproducing experimental cross sections of quasielastic charge exchange reactions, a largely overlooked constraint for optical potentials. We also examine to what degree the WLH model satisfies the dispersion relation and its significance in constructing phenomenological optical potentials. Exploring these properties of the WLH optical potential helps lay the groundwork for next-generation phenomenological global optical potentials informed by microscopic physics and with quantified uncertainties that are suitable for reactions involving rare isotopes. |
Wednesday, October 13, 2021 12:30PM - 12:42PM |
KM.00006: Considering non-locality in the optical potentials within eikonal models Chloë Hebborn, Filomena Nunes Reactions at high energies (E>100A MeV), such as breakup and knockout, are often used to probe the structure of nuclei away from stability. The key ingredient of any reaction analyses are the effective interactions between the clusters, known as the optical potentials. Such potentials are intrinsically non-local, and their non-locality affects significantly reactions observables. In this talk, I will start by presenting the effects of non-locality in the optical potentials for transfer observables at E>100A MeV. Our analysis shows that these reaction observables are significantly impacted by non-locality in the optical potentials. Since knockout reactions are dominated by stripping (transfer to inelastic channels), non-locality is expected to have a large effect on knockout observables too. In the energy regime of breakup and knockout, the eikonal approximation is the tool of choice to interpret these reactions because of its simplicity. In the second part of this talk, I will discuss different avenues for extending the eikonal method to include non-local interactions. |
Wednesday, October 13, 2021 12:42PM - 12:54PM |
KM.00007: Quantified impact of the Pauli exclusion principle on the nucleus-nucleus interaction Kyle S Godbey, Sait A Umar, C. Simenel The Pauli exclusion principle plays a crucial role as a pillar of many-body quantal systems comprised of fermions. It also induces a “Pauli repulsion” in the interaction between heavy ions. It has been shown in [1] that the Pauli repulsion widens the nucleus-nucleus potential barrier, thus hindering sub-barrier fusion. To extend this picture, we use the Pauli kinetic energy (PKE) obtained by studying the nuclear localization function [2]. This approach is employed in both the static density constrained frozen Hartree-Fock and in the dynamic density constrained time-dependent Hartree-Fock microscopic methods. Significant effects are seen at first contact of the reaction nuclei and deep inside the fusion barrier. Furthermore, varying effects are seen for dynamic proton/neutron contributions inside the barrier, seen as an effect of multinucleon transfer. The PKE is shown to make a significant contribution to statically and dynamically derived nuclear interaction potentials. |
Wednesday, October 13, 2021 12:54PM - 1:06PM |
KM.00008: Effect of Electromagnetic Fields on Deformed AdS5 Models Davoud Masoumi, Leila Shahkarami, Farid Charmchi Many studies have investigated the vast aspects of the Schwinger effect by using gauge/gravity duality; however, the Schwinger effect in QCD-like gauge theories, especially where both electric and magnetic fields are simultaneously present, still need to be scrutinized. We use the deformed AdS5 background metric for the gravity side of AdS/QCD correspondence since the potential of heavy quarks produced by this background metric agrees with experimental data. We use both potential analysis and calculation of the pair-production rate Γ to study the response of the QCD-like gauge theory to an external electromagnetic field and show that the two approaches agree. We identify critical electric fields ES and EC as lower and upper bounds of a range in which pair production can occur only by tunneling through a potential barrier. Below ES, the potential barrier is insurmountable, and pair production cannot happen. Above EC, there is no potential barrier to restrict the pair production. In addition, we find that a magnetic field perpendicular to the electric field suppresses Γ and increases ES. In contrast, a pure parallel magnetic field does not affect the system's response to an external electric field, but it enhances Γ when a perpendicular magnetic field is also present. |
Wednesday, October 13, 2021 1:06PM - 1:18PM |
KM.00009: Disruption of Relativistic, QED, QCD, Standard Nuclear Formalism, by a lighter Mechanics, post-Quantum, Quaternal, Unified with Unitary Electron Spin: the QUEST Theory Claude Massot As Ptolemeus predictions were quite good despite their flawed Physics, the popular Standard QED, QCD, Relativistic Models, can be challenged as resting on false principles. My disruptive QUESTheory recalls the forgotten principle of parsimony, shrinks Heisenberg's uncertainty by 137 and restricts the Standard particles Zoo, to 2 quarkless/gluonless, stable, 4waves/particles of spin 1: the proton and the electron, with a dual/complex mass ( or quaternal at high energy). The neutron, is not a fermion but a neutronic hydrogen sub-atom, with its electron spinning on a luminic unstable, low orbit. The nucleus, then, contains only protons and electrons, linked by a 137 times stronger, unified, electric force, as also gravitation, no longer stemming from space/time curvature, but from a residual tiny electric force. The fusion mass defect, could result from a violation of gravitational and inertial mass equivalence in the nucleus. A direct measure of the mass of the neutron, so far, never weighted, is urgent for closing this theoretical gap, potential culprit, in all failed fusion attempts of energy production, besides the H Bomb! These fundamental disruptions lead me to look for radical innovative strategies in harvesting the huge inner, still untamed, much needed, fusion energy. |
Wednesday, October 13, 2021 1:18PM - 1:30PM |
KM.00010: Probing the Neutron Skin of Mirror Nuclei with Coupled-cluster Theory Samuel J Novario, Stefano Gandolfi, Gaute Hagen, Diego Lonardoni An accurate determination of the neutron-skin thickness of nuclei can have important implications |
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