High Energy / Nuclear Theory / RIKEN seminars
# [NT/RIKEN seminar] Two-baryon interactions from lattice QCD

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US/Eastern

Description

It has been over three decades since the first two-baryon

studies from lattice QCD were performed. Despite algorithmic

improvements and increases in computational resources since then,

there remains disagreement on results from various groups in the

lattice community. A major barrier in resolving these discrepancies is

the poor signal-to-noise ratio for baryons, which needs to be overcome

with modern methods. In this seminar, I will begin by covering various

techniques and formalism that have become standard in lattice

spectroscopy. This will include the use of distillation (and its

stochastic variant) to treat all-to-all quark propagation; a

variational method, which can help to reduce unwanted excited states

while allowing for several desired states to be extracted; and the

L\"uscher two-particle formalism, which relates finite-volume energies

to infinite-volume scattering amplitudes. I will then present our

recent results for two nucleon S-wave interactions in both isospin

channels, computed at the SU(3)-flavor-symmetric point corresponding

to $m_\pi \approx 714$ MeV. These results strongly disfavor the

presence of any bound states at this pion mass, which contradicts some

of the calculations in the literature. Further, our recent results for

the $H$ dibaryon---also using an SU(3)-symmetric setup, but

corresponding to $m_\pi \approx 420$ MeV---show appreciable dependence

on the lattice spacing. This could explain some of the discrepancies

in the literature. However, I will discuss other possibilities, as

well as future directions for spectroscopy.