Session H15: Mini-Symposium: Toward an Effective Field Theory Description of Nuclear Forces

The importance of few-nucleon forces in chiral EFT

TBD   

Full-Bayesian model calibration for chiral EFTs

In the past few decades, the development of quantum many-body algorithms has progressed to yield highly accurate and precise calculations of nuclear observables. Coinciding with this, high-quality models of nuclear interactions have seen rapid advancements. One such class of interactions are those derived from Effective Field Theories (EFTs). When paired with modern many-body techniques, EFT models return similar results to well-tested phenomenological models. However, current calculations of nuclear properties are largely devoid of proper uncertainty estimation. With EFTs, a natural estimation of uncertainty exists through the truncation of the EFT perturbation.   

Uncertainty estimates for muon capture on the deuteron in chiral effective field theory

Muon capture on the deuteron is a two-body electroweak process that can provide information on the properties of the electroweak current in nuclear effective field theory but also the three-body force in the nuclear Hamiltonian. Uncertainty analysis of the dominant channels is important for a careful analysis of forthcoming experimental data. We quantify the theoretical uncertainties of chiral effective-field-theory predictions of the muon-deuteron capture rate from the relevant neutron-neutron partial wave channels in the final state. We study the dependence on the cutoff used to regularize the interactions, low-energy constants calibrated using different fitting data and strategies, and truncation of the effective field-theory expansion of the currents. I will discuss recent results on the calculation of the rate for this process and corresponding uncertainty estimates.   

Beta-delated proton emission with Halo Effective Field Theory

Halo nuclei offer an interesting way to study beta-decay in nuclear systems. For example, recently experiments measured a surprisingly large branching ratio for beta-delayed proton emission in 11Be. A resonance that can enhance the rate for this process has also been reported. In halo effective field theory, halo nuclei like 11Be can be described in a systematic low-energy expansion facilitated by the separation of scales between halo matter radius and core radius. I will describe our recent calculation of beta-delated proton emission within this framework and how it relates to recent experimental results.   

Diagrammatic Approach to Four-Boson Systems in Effective Field Theory

We use a diagrammatic approach to study four-boson systems using effective field theory with both two- and three-body contact interactions. Four-boson calculations (see, e.g., Ref.[1]) have been hindered by deeply bound trimers (i.e., Efimov states) which appear at relatively high cutoffs. We present a method to systematically include the deeply bound trimers in four-boson calculations, which allows us to compute tetramer binding energies at high cutoffs where deeply bound trimers exist. By using high cutoffs and including the deeply bound trimers in our calculations, we demonstrate numerically that high cutoffs are in fact needed to obtain converging and accurate tetramer binding energies. We also study the correlation between the trimer and tetramer binding energies by approaching the unitary limit. Our results agree with Ref.[2] and may be used as a benchmark for similar calculations. This method could also be used to study four-nucleon systems by including spin and isospin.

[1]Platter, H. W. Hammer, and U.-G. Meissner, The Four boson system with short range interactions, Phys. Rev. A 70, 052101 (2004), arXiv:cond-mat/0404313.

[2]Deltuva, Efimov physics in bosonic atom-trimer scattering, Phys. Rev. A 82, 040701 (2010), arXiv:1009.1295 [physics.atm-clus].   

Wave function matching for the quantum many-body problem

We introduce a new approach for solving quantum many-body systems called wave function matching. Wave function matching transforms the interaction between particles so that the wave functions at short distances match that of an easily computable interaction. This allows for calculations of systems that would otherwise be impossible due to problems such as Monte Carlo sign cancellations. We apply the method to lattice Monte Carlo simulations of light nuclei, medium-mass nuclei, neutron matter, and nuclear matter. We use interactions at next-to-next-to-next-to-leading order in the framework of chiral effective field theory and find good agreement with empirical data. These results are accompanied by new insights on the nuclear interactions that may help to resolve long-standing challenges in accurately reproducing nuclear binding energies, charge radii, and nuclear matter saturation in ab initio calculations.   

Two-nucleon scattering on quantum computer

Quantum computing is a new and promising tool in nuclear physics. In the present NISQ era, noise mitigation is crucial for quantum algorithms to work. I will be talking about the results of our work which uses the quantum algorithms Variational Quantum Eigensolver (VQE) and Quantum Subspace Expansion (QSE) to calculate two nucleon phase shifts starting from the ground state energy and wavefunction of the deuteron. I will also talk about the various noise mitigation techniques that we employed to deal with noise present in contemporary quantum hardware.