# Bulletin of the American Physical Society

# 2020 Fall Meeting of the APS Division of Nuclear Physics

## Volume 65, Number 12

## Thursday–Sunday, October 29–November 1 2020; Time Zone: Central Time, USA

## Session KJ: Mini-Symposium: Nuclear Physics from Effective Field Theory and Lattice Field Theory III |
Hide Abstracts |

Chair: Matthias Schindler, U of South Carolina |

Saturday, October 31, 2020 8:30AM - 8:42AM |
KJ.00001: Effective field theory for deformed odd-mass nuclei Thomas Papenbrock, Hans Weidenm{\"u}ller This talk presents an effective field theory (EFT) for deformed odd-mass nuclei. These are described as a nucleon coupled to an axially symmetric core. The power counting exploits the separation of scales between low-lying rotations and higher-lying excitations of the core. At leading order, the core and the nucleon are coupled by universal derivative terms. These consist of a covariant derivative and a gauge potential and they account for Coriolis forces. Odd-mass nuclei with rotational band heads that are close in energy and differ by one unit of angular momentum are triaxially deformed. For band heads that are well separated in energy, triaxiality becomes a subleading effect. The EFT is developed up to next-to-leading order and applied to $^{239}$Pu and $^{187}$Os. The EFT presents a model-independent approach to the particle-rotor system that is capable of systematic improvement. The work is available as arXiv:2005.11865. [Preview Abstract] |

Saturday, October 31, 2020 8:42AM - 8:54AM |
KJ.00002: Towards Matching the Double-$\beta$ Decay Amplitude in Effective Field Theory to Lattice QCD Saurabh Kadam, Zohreh Davoudi The ongoing search for neutrinoless double $\beta$ process $(0\nu\beta\beta)$ is crucial for determining the Majorana nature of neutrinos. To relate the rate of these processes with the underlying standard model and beyond standard model interactions, the corresponding nuclear matrix elements must be constrained reliably from theory. As an effort in that direction, we present here a way to constrain the two-neutrino $\beta$ decay amplitude, a process closely related to $0\nu\beta\beta$, using lattice quantum chromodynamics (LQCD). The Minkowski infinite volume amplitude of two-hadrons with two-weak current insertions is constructed in the pionless effective field theory at the next-to-leading order. A formalism is then provided to constrain this two-hadron amplitude using a LQCD four-point correlation function in Euclidean and finite-volume spacetime, similar to the work done earlier for single hadron amplitudes. This formalism can be extended to allow the determination of the important $0\nu\beta\beta$ decay amplitude with LQCD input in upcoming years. [Preview Abstract] |

Saturday, October 31, 2020 8:54AM - 9:06AM |
KJ.00003: Theoretical uncertainty for neutrinoless double-beta decay from chiral EFT Eduardo Coello Perez We study how the uncertainties from chiral effective field theory (EFT) propagate to the matrix element associated to neutrinoless double-beta decay. To this end, we employ a surrogate model with nucleon droplets that mimic the dynamics of the valence nucleons in the systems of interest, and let the nucleons in them interact via chiral nucleon-nucleon and three-nucleon forces fitted to scattering data and the binding energies and radii of deuteron, triton and helium. The droplets are fitted to the energies of 0+ states in the nuclei of interest. We employ Markov-chain Monte Carlo methods to sample a large number of low-energy constant (LEC) sets and calculate the relevant wave functions and the diverse components of the neutrinoless double-beta decay matrix element for each one of them. Similarly, we sample the unknown LEC in the neutrinoless double-beta decay operator allowing us to take into account the short-distance contribution to the matrix element. The resulting distributions for the latter possess intervals with 95\% degree-of-belief which widths are smaller than the spread in the matrix element resulting from its calculation with the diverse nuclear models. [Preview Abstract] |

Saturday, October 31, 2020 9:06AM - 9:18AM |
KJ.00004: Neutrinoless Double Beta Decay from Lattice QCD: The Long-Distance $\pi^- \to \pi^+ e^- e^-$ Amplitude William Detmold, David Murphy Observation of neutrinoless double beta decay ($0\nu\beta\beta$) would have important consequences as it would demonstrate that the neutrino is a Majorana particle and that lepton number conservation is violated in nature and provide information on the absolute scale of neutrino masses. Relating experimental constraints on $0\nu\beta\beta$ decay rates to the neutrino masses requires theoretical input in the form of non-perturbative nuclear matrix elements which remain difficult to calculate reliably. In this talk, a first step toward providing a general lattice QCD framework for computing long-distance $0\nu\beta\beta$ matrix elements in the case where the decay is mediated by a light Majorana neutrino will be discussed. The relevant formalism is developed and then tested by computing the simplest such matrix element describing an unphysical $\pi^- \to \pi^+ e^- e^-$ transition. The resulting lattice data is then fit to next-to-leading-order chiral perturbation theory, allowing a fully-controlled extraction of the low energy constant governing the transition rate, and future prospects are discussed [Preview Abstract] |

Saturday, October 31, 2020 9:18AM - 9:30AM |
KJ.00005: Investigation of electroweak processes in light nuclei with Chiral Effective Field Theory Garrett King, Saori Pastore, Maria Piarulli Understanding electroweak interactions in nuclei is crucial for future fundamental physics investigations, such as neutrinoless double beta decay experiments and long-baseline experiments measuring neutrino oscillation parameters. In this work, we present {\it ab initio} calculations of low-energy electroweak processes in light nuclei for vanishing and moderate momentum transfer using variational and Green's Function Monte Carlo methods. Calculations of nuclear matrix elements employ the Norfolk potential, a high-quality local chiral interaction containing two- ($NN$) and three-body ($3N$) forces. Employing one- and two-body axial currents consistent with the Norfolk potential, we calculate Gamow-Teller (GT) reduced matrix elements and one- and two-body GT transition densities for $A \le 10$ nuclei. These studies provide a validation of nuclear many-body correlations and currents entering {\it ab initio} calculations and demonstrate the behavior of individual contributions to the axial current in the limit of vanishing momentum transfer. Additionally, we calculate muon capture rates, allowing us to validate contributions to the electroweak charge and current operators at momentum transfers on the order of the muon mass. [Preview Abstract] |

Saturday, October 31, 2020 9:30AM - 9:42AM |
KJ.00006: Magnetic and Axial Two-Nucleon Currents in a Combined Large-$N_c$ and Pionless Effective Field Theory Expansion Thomas Richardson, Matthias Schindler Combining the large-$N_c$ expansion with the pionless effective field theory (EFT$_{\pi\hskip-0.40em /}$) expansion provides theoretical constraints on the low energy coefficients that accompany each operator in the effective theory. In EFT$_{\pi\hskip-0.40em /}$, magnetic and axial two-nucleon contact terms contribute to a variety of electroweak processes such as the deuteron magnetic moment, radiative neutron capture, and proton-proton fusion. The large-$N_c$ expansion indicates that the isoscalar magnetic coupling is suppressed relative to the isovector coupling, which offers a partial explanation of the suppression found in data. We find a similar result for a general two-nucleon axial current that justifies the omission of one of the terms in processes such as neutrino-deuteron scattering. [Preview Abstract] |

Saturday, October 31, 2020 9:42AM - 9:54AM |
KJ.00007: Electric polarizability of hadrons from Lattice QCD Hossein Niyazi, Andrei Alexandru, Frank X. Lee Electric and magnetic polarizabilities are two of the fundamental prop- erties of hadrons which help us understand the distribution of charge and currents inside hadrons and how they respond to external electromagnetic fields. For nucleons, these values are determined experimentally from Comp- ton scattering. For charged pions, the experiments are more challenging since no free pion target is available and the results are less precise, but a number of experiments are planned that will improve the accuracy. Lattice QCD can be used to compute hadron properties as determined by quark and gluon dynamics, providing results that are complementary to other theoret- ical approaches. In this talk I will review the lattice QCD methods used to compute hadron polarizabilities, focusing on electric polarizability, and present our results. [Preview Abstract] |

Saturday, October 31, 2020 9:54AM - 10:06AM |
KJ.00008: Electric dipole moments of trinucleon systems in pionless effective field theory Zichao Yang, Emanuele Mereghetti, Lucas Platter, Matthias Schindler, Jared Vanasse A permanent electric dipole moment (EDM) is evidence of parity and time-reversal violations (PVTV), and thus, of charge conjugation and parity violation(CPV). The measurement of EDMs of few-nucleon systems could help to impose constraints on the TV sources and could provide access to neutron and proton EDMs. Three-nucleon systems, such as the triton and helium-3 have binding momenta much smaller than the mass of pion and are therefore not sensitive to details of pion-exchange. For these, we can use the so-called pionless effective field theory for the calculation of observables which is well tested EFT approach with a well-understood power counting. We calculated the EDM of the triton and helium-3 at leading order without Coulomb interaction in pionless EFT. We used a minimal set of five low energy constants (LECs) for PVTV nucleon-nucleon interactions to express the EDM of triton and helium-3 and compare our results with the previously known chiral EFT results by matching the coupling constants. [Preview Abstract] |

Saturday, October 31, 2020 10:06AM - 10:18AM |
KJ.00009: Magnetic moments for \(A \le 3\) nuclei from chiral effective field theory Soham Pal, Shiplu Sarker, Pieter Maris, James P. Vary, Patrick J. Fasano, Mark A. Caprio We present recent no-core shell model (NCSM) calculations of magnetic moments in \(A \le 3\) nuclei with chiral-EFT improved M1 operator and LENPIC interactions. We have derived the M1 operator from chiral-EFT electromagnetic currents up to N2LO in power counting, including two-body pion-exchange terms. We focus the discussion on the corrections that arise from the two-body pion-exchange terms, the convergence with respect to the NCSM basis space parameters, and the impact of coordinate space regulators. [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