Nuclear physics uncertainties in light hypernuclei

The energy levels of light hypernuclei are experimentally accessible observables that contain valuable information about the interaction between hyperons and nucleons. In this work we study strangeness S = -1 systems H-3,4(Lambda) and He-4,5(Lambda) using the ab initio no-core shell model (NCSM) with realistic interactions obtained from chiral effective field theory (chi EFT). In particular, we quantify the finite precision of theoretical predictions that can be attributed to nuclear physics uncertainties. We study both the convergence of the solution of the many-body problem (method uncertainty) and the regulator and calibration-data dependence of the nuclear chi EFT Hamiltonian (model uncertainty). For the former, we implement infrared correction formulas and extrapolate finite-space NCSM results to infinite model space. We then use Bayesian parameter estimation to quantify the resulting method uncertainties. For the latter, we employ a family of 42 realistic Hamiltonians and measure the standard deviation of predictions while keeping the leading-order hyperon-nucleon interaction fixed. Following this procedure we find that model uncertainties of ground-state Lambda separation energies amount to approximate to 20 (100) keV in H-3(Lambda) (H-4(Lambda), He) and approximate to 400 keV in He-5(Lambda). Method uncertainties are comparable in magnitude for the H-4(Lambda), He 1(+) excited states and He-5(Lambda), which are computed in limited model spaces, but otherwise are much smaller. This knowledge of expected theoretical precision is crucial for the use of binding energies of light hypernuclei to infer the elusive hyperon-nucleon interaction.

Automated summary

The study utilizes realistic interactions obtained from chiral effective field theory (chi EFT) and the ab initio no-core shell model (NCSM) to investigate the energy levels of H-3,4(Lambda) and He-4,5(Lambda) systems with strangeness S = -1. The research focuses on quantifying the finite precision of theoretical predictions related to nuclear physics uncertainties. Results show that model uncertainties of ground-state Lambda separation energies are approximately 20 (100) keV in H-3(Lambda) (H-4(Lambda), He), and approximately 400 keV in He-5(Lambda). Method uncertainties also play a significant role in certain excited states.