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 FJ: Mini-Symposium: Nuclear Physics from Effective Field Theory and Lattice Field Theory II |
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Chair: Martha Constantinou, Temple |
Friday, October 30, 2020 2:00PM - 2:12PM |
FJ.00001: Charged Multi-Hadron Systems in Lattice QCD+QED Michael Wagman QED effects must be included in lattice QCD calculations in order to make Standard Model predictions with percent-level accuracy, to constrain isospin-breaking effects in hadronic and nuclear EFTs, and to study the interplay of nonperturbative QED and QCD effects in nuclei. Lattice QCD+QED calculations of single-hadron masses and matrix elements have recently been performed by several groups and the corresponding formalism for matching to hadronic EFTs including QED finite-volume effects has been developed. In this talk, I will discuss lattice QCD+QED calculations of charged multi-hadron systems, which face additional challenges from the presence of Coulomb interactions that are nonperturbative in large volumes. I will present lattice QCD+QED results by the NPLQCD and QCDSF collaborations for the ground-state energies of systems of 1-12 charged and neutral mesons as well as 1-3 charged and neutral nucleons in multiple finite volumes. These lattice QCD+QED results are then used to constrain two-body and three-body couplings for charged and neutral mesons in a non-relativistic hadronic EFT. The practical range of volumes for which Coulomb effects can be treated perturbatively in EFT is discussed. [Preview Abstract] |
Friday, October 30, 2020 2:12PM - 2:24PM |
FJ.00002: Improved description of light nuclei through chiral effective field theory at leading order Mario S\'anchez S\'anchez I present a rearrangement of the most commonly invoked version of the two-nucleon chiral potential so that the low-lying amplitude zero of the 1S0 partial wave is subsumed at first order in the effective expansion. Adopting other partial waves from the LENPIC interaction, I show through a no-core shell model calculation how such modification yields an improved description of ground-state energies and point-proton radii of three test nuclei, namely 3H, 4He and 6He. I discuss possible implications of this proposal and point out some future research lines. This presentation is based upon the recent preprint \underline {https://arxiv.org/abs/2002.12258} [Preview Abstract] |
Friday, October 30, 2020 2:24PM - 2:36PM |
FJ.00003: Spurious poles in hadronic three-particle problems Martin Ebert, Hans-Werner Hammer, Akaki Rusetsky The particle-dimer picture is a useful tool to simplify the three-particle problem by including information about the two-particle system. However, in higher orders the dimer propagator can exhibit spurious poles. We present a non-perturbative approach to deal with this problem and compare to fully perturbative schemes. The proposed approach might prove to be more convenient for the generalization in a finite volume. The method is tested with a Yamaguchi model potential. [Preview Abstract] |
Friday, October 30, 2020 2:36PM - 2:48PM |
FJ.00004: ABSTRACT Rescheduled to Session SJ |
Friday, October 30, 2020 2:48PM - 3:00PM |
FJ.00005: Structure of Three-Body Hypernuclei Fabian Hildenbrand, Hans-Werner Hammer We calculate the structure of three-body hypernuclei with $S=-1$ using pionless effective field theory at leading order in the isospin $I=0$ and $I=1$ sectors. In both sectors, three-body hypernuclei arise naturally from the Efimov effect and a three-body parameter is required at leading order. We apply our theory to the hypertriton and the hypothetical $\Lambda$nn bound state and calculate the corresponding scaling factors. Moreover, we discuss constraints on the existence of the $\Lambda$nn bound state. In particular, we elucidate universal correlations between different observables and provide explicit calculations of wave functions and matter radii. In addition, we discuss the lifetime and branching ratios of the hypertriton in an effective theory with a fundamental deuteron and discuss the impact of the binding energy in the light of recent experimental results. [Preview Abstract] |
Friday, October 30, 2020 3:00PM - 3:12PM |
FJ.00006: Do we need more than two-body forces at leading order in chiral effective field theory ? Chieh-Jen Yang We investigate the importance of higher-body forces for describing many-body systems. Based on simple analytical arguments, we show that at least some of the three-body diagrams in chiral effective field theory ($\chi$EFT)---which were conventionally regarded as next-to-next-to-leading order (NNLO)---are necessary at leading order (LO) for systems with more than $A\sim13-26$ number of nucleons. We perform numerical calculations with no-core-shell-model (NCSM) and coupled-cluster (CC) methods to verify our assumption. We found that only after the entrance of C$_D$ and C$_E$ terms in the three-body force can a correct $^{16}$O pole structure be restored at LO---a feature which has never been achieved previously with an EFT which satisfies the renormalization-group (RG) condition. We also check the importance of four-body force in larger systems by performing ab-initio nuclear matter calculations with two- and three-body forces. The LO results suggest that, without four-body force, RG-invariance and reasonable saturation cannot be achieved at the same time. Our findings serve as a crucial step for developing a model-independent power counting in EFT. [Preview Abstract] |
Friday, October 30, 2020 3:12PM - 3:24PM |
FJ.00007: Three-particle scattering amplitudes from lattice QCD Fernando Romero-Lopez Three-particle observables are the present frontier in lattice QCD scattering calculations. In this talk, I will report on the extraction of three-particle scattering amplitudes from lattice simulations. I will review the existing theoretical approaches and their relation, and comment on recent generalizations to include nonidentical particles and three-particle resonances. I will also address the current status of lattice simulations, including novel results in the $\varphi^4$ theory, and for three charged pions in QCD. [Preview Abstract] |
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