Nuclear Theory Seminar - Andrew Hanlon, Kent State U

Date
Thu, May 15, 2025 2:00 pm - 3:00 pm
Location
PSC 2136

Description

Speaker: Andrew Hanlon, Kent State University


Title: On the binding of two nucleons from lattice QCD

Abstract: Lattice QCD calculations of two- and three-hadron scattering amplitudes are on firm
footing from a theoretical standpoint. This has led to the successful extraction of scattering
amplitudes for several systems, with most studies involving the scattering of two mesons.
However, there have been significant discrepancies between different groups when using these
methods to extract the binding energy of two nucleons. Calculations involving baryons are
significantly more challenging due to the increased severity of the exponentially decaying
signal-to-noise ratio. This issue can lead to a large systematic error in the extraction of
multi-hadron finite-volume energies used to constrain the scattering amplitudes. This
systematic can be difficult, or impossible, to accurately quantify and likely plays a significant
role in the observed discrepancies of the binding energies. With the use of modern lattice
calculations and analysis methods, the leading contamination of the finite-volume energies from
higher-lying states can be suppressed. All results for the binding of two baryons have been
consistent when utilizing these state-of-the-art methods, which have also been in qualitative
agreement with an alternative approach for calculating the binding energy called the HAL
QCD potential method. In this talk, I will give some historical context on the disagreement
in the literature and then present recent results at a pion mass of ∼ 714 MeV which strongly
disfavors the binding of two nucleons.