Bulletin of the American Physical Society
6th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Sunday–Friday, November 26–December 1 2023; Hawaii, the Big Island
Session E13: Nuclear Theory I |
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Chair: Yusuke Nishida, Tokyo Institute of Technology Room: Hilton Waikoloa Village Kona 2-3 |
Wednesday, November 29, 2023 7:00PM - 7:15PM |
E13.00001: Quantum Monte Carlo Calculations of Magnetic Moments for A ≤ 10 Nuclei Graham Chambers-Wall, Garrett B King, Alex Gnech, Maria Piarulli, Saori Pastore Searches for new physics in experiments such as precision beta decay measurements, neutrinoless double beta decay, and neutrino oscillation experiments will feature electroweak phenomena. These experiments require input from theory, and an accurate understanding of nuclear dynamics is needed to extract new physics. In particular, an accurate electromagnetic current and an understanding of model dependencies is vital for this effort. We report Quantum Monte Carlo calculations of magnetic form factors and magnetic moments for A ≤ 10 nuclei using the Norfolk two- and three-nucleon (NV2+3) chiral interactions and one- and two-body electromagnetic currents. We use low-energy constants (LECs) to parameterize these currents up to next-to-next-to-next-to leading order (N3LO). The form factor calculations show agreement with data even in the high momentum transfer region at N3LO. Additionally, the magnetic moment calculations agree with data for both models considered. |
Wednesday, November 29, 2023 7:15PM - 7:30PM |
E13.00002: Chiral effective field theory corrections to ab initio M1 and Gamow-Teller observables in light nuclei Patrick J Fasano, Mark A Caprio, Pieter Maris, James P Vary, Shiplu Sarker, Soham Pal Ab initio nuclear theory attempts to predict the properties of atomic nuclei, starting from nucleons and their interactions. Modern realistic interactions, along with consistent electroweak operators, are derived systematically from chiral effective field theory (χEFT). We use the χEFT-derived magnetic dipole (M1) and Gamow-Teller (GT) operators to calculate the properties of light nuclei (A ≤ 17) within the Low Energy Nuclear Physics International Collaboration (LENPIC) formalism. We solve the quantum many-body problem using the no-core configuration interaction (NCCI), or no-core shell model (NCSM), approach and find that the inclusion of |
Wednesday, November 29, 2023 7:30PM - 7:45PM |
E13.00003: Emergent geometry and duality in the carbon nucleus Dean J Lee The carbon atom provides the backbone for the complex organic chemistry composing the building blocks of life. The physics of the carbon nucleus in its predominant isotope, 12C, is similarly full of multifaceted complexity. Here we provide a model-independent density map of the geometry of the nuclear states of 12C using the ab initio framework of nuclear lattice effective field theory. We find that the well-known but enigmatic Hoyle state is composed of a “bent-arm” or obtuse triangular arrangement of alpha clusters. We identify all of the low lying nuclear states of 12C as having an intrinsic shape composed of three alpha clusters forming either an equilateral triangle or an obtuse triangle. The states with the equilateral triangle formation also have a dual description in terms of particle-hole excitations in the mean-field picture. |
Wednesday, November 29, 2023 7:45PM - 8:00PM |
E13.00004: Using integral relations to improve ab initio structure and reaction calculations for light nuclei Kenneth M Nollett, Abraham R Flores, Satish Chandran, Arik Mahbub The variational Monte Carlo and Green's function Monte Carlo methods, which use random sampling in position space instead of basis expansions, have been used in many accurate ab initio calculations of energy levels and transition probabilities in light nuclei. However, they have had more difficulty with "long-range" properties like scattering amplitudes and the large-radius tails of bound states. It can be hard to produce reasonable variational trial functions that capture both pairwise interactions of nucleons at short range and the clustering properties that dominate at long range. It can also be difficult to find Monte Carlo sampling schemes that probe the low-probability tails and "off-diagonal" quantities effectcively. We will describe calculations that mitigate these difficulties by avoiding direct calculation of long-range amplitudes in the wave function and instead finding them from integrals over better-computed short-range parts of the wave function: single-particle spectroscopic overlaps at A ≤ 9, alpha-removal spectroscopic overlaps at A = 7, true scattering in A = 4,5 systems, and scattering at A = 5 using pseudo-bound variational wave functions. |
Wednesday, November 29, 2023 8:00PM - 8:15PM |
E13.00005: Semidefinite programs for few-nucleon systems Scott Lawrence In a quantum mechanical system, the norm of any state must be non-negative; equivalently, for any observable O, the expectation value 〈O†O〉must be non-negative. It was recently proposed (by Han, Hartnoll, and Kruthoff; later explored by Berenstein and Hulsey among many others) to turn this observation into a computational method---sometimes terms the quantum-mechanical bootstrap---for probing the ground state of an arbitrary Hamiltonian. The result is a semidefinite program (a particular convex optimization task) which, when solved, yields a lower bound on the ground-state energy, along with estimates of other expectation values in the ground state. The same approach has been applied to lattice field theories, including at finite fermion density. In this talk we show how the method may be applied to few-nucleon systems using a Hamiltonian from pionless EFT. |
Wednesday, November 29, 2023 8:15PM - 8:30PM |
E13.00006: An adiabatic hyperspherical treatment of halo nuclei in the few body sector Michael D Higgins, Chris H Greene An area of the few body sector that provides a natural class of systems near the unitarity limit is low-energy nuclear physics. These systems include halo nuclei, which are good candidate systems to study the near-unitarity limit and universality. Two–neutron halos have been extensively studied, such as 6He, 9B,11Li, 12Be, and 12C. With the large neutron-neutron (nn) 1S0 scattering length (as≅-18.5 fm), halo nuclei are good candidates to study universal physics near the unitarity limit and the possible emergence of Efimov physics in Borromean systems or the scattering continuum. In this work, we use the adiabatic hyperspherical representation to study halo nuclei consisting of four neutrons. The adiabatic hyperspherical representation has been extensively applied to few-body systems, in which a description of all possible reaction pathways is treated on an equal footing from treating a collective coordinate, the hyperradius, adiabatically. This work focuses on the 4He+4n system, which has been of recent theoretical interest sparked by the 2022 experiment by Duer et. al. that found a low-energy 4n signal in the missing mass spectrum of the 8He(p,p4He)4n reaction. This work aims to provide theoretical insight into the qualitative and quantitative nature of the five-body scattering continuum and possible universal physics arising in four-neutron halos from the nn interaction. |
Wednesday, November 29, 2023 8:30PM - 8:45PM |
E13.00007: Delta-Delta intermediate states in nucleon-nucleon scattering from a large-Nc perspective Matthias R Schindler, Thomas Richardson, Roxanne P Springer The large-Nc picture, where Nc is the number of colors, successfully explains some features of the nucleon-nucleon (NN) interactions. This success is somewhat surprising. In the large-Nc limit, the nucleon and the Delta isobar become degenerate, and the Delta plays an important role for the consistency of the large-Nc approach in the single-baryon sector. However, large-Nc analyses of NN interactions so far have not taken into account intermediate Delta-Delta states. We analyze the impact of including Delta intermediate states in NN scattering and provide a possible explanation for the success of “Delta-less” large-Nc approaches. |
Wednesday, November 29, 2023 8:45PM - 9:00PM |
E13.00008: Infrared Phases of 2d QCD from Qubit Regularization Hanqing Liu, Tanmoy Bhattacharya, Shailesh Chandrasekharan Qubit regularization provides a framework for studying gauge theories through finite-dimensional local Hilbert spaces, presenting opportunities for digital quantum simulations. In this talk, we investigate the IR phases of 2d QCD with the $mathrm{SU}(N)$ gauge group via qubit regularization. In the continuum, a 2d $mathrm{SU}(N)$ gauge theory coupled to a single flavor of fundamental massless Dirac fermions can be bosonized into an $mathrm{SO}(2N)_1/mathrm{SU}(N)_1$ Wess-Zumino-Witten (WZW) model or a compact boson. On the lattice, utilizing a strong-coupling expansion of the qubit-regularized Kogut-Susskind Hamiltonian with the assistance of a generalized Hubbard coupling, we demonstrate that the continuum physics can be reproduced by an XXZ spin chain, together with a gapped phase. We also show the existence of a confinement/deconfinement (screening) transition. These arguments are verified numerically in the $mathrm{SU}(2)$ case using the tensor network approach. Our numerical results reveal that the lattice model has a central charge of 1, and its spectrum can be understood as the $mathrm{SU}(2)_1$ WZW model perturbed by a tiny marginally irrelevant operator, which can be tuned away by the Hubbard coupling. The confinement/deconfinement transition is also verified numerically by measuring the string tensions. |
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