# Baryon-Baryon Interactions and Spin-Flavor Symmetry from Lattice Quantum Chromodynamics

## TL;DR

This study uses lattice QCD to analyze baryon-baryon interactions at a symmetric quark mass point, revealing approximate SU(6) and SU(16) symmetries and identifying bound states in certain channels, consistent with earlier findings.

## Contribution

First lattice QCD calculation of two-baryon interactions at SU(3) flavor symmetry with heavy quark masses, demonstrating emergent spin-flavor symmetries and bound states.

## Key findings

- Identification of bound states in specific baryon channels.
- Evidence for approximate SU(6) and SU(16) symmetries in baryon interactions.
- Confirmation of two-nucleon bound states at heavy quark masses.

## Abstract

Lattice quantum chromodynamics is used to constrain the interactions of two octet baryons at the SU(3) flavor-symmetric point, with quark masses that are heavier than those in nature (equal to that of the physical strange quark mass and corresponding to a pion mass of $\approx 806~\tt{MeV}$). Specifically, the S-wave scattering phase shifts of two-baryon systems at low energies are obtained with the application of L\"uscher's formalism, mapping the energy eigenvalues of two interacting baryons in a finite volume to the two-particle scattering amplitudes below the relevant inelastic thresholds. The values of the leading-order low-energy scattering parameters in the irreducible representations of SU(3) are consistent with an approximate SU(6) spin-flavor symmetry in the nuclear and hypernuclear forces that is predicted in the large-$N_c$ limit of QCD. The two distinct SU(6)-invariant interactions between two baryons are constrained at this value of the quark masses, and their values indicate an approximate accidental SU(16) symmetry. The SU(3) irreducible representations containing the $NN~({^1}S_0)$, $NN~({^3}S_1)$ and $\frac{1}{\sqrt{2}}(\Xi^0n+\Xi^-p)~({^3}S_1)$ channels unambiguously exhibit a single bound state, while the irreducible representation containing the $\Sigma^+ p~({^3}S_1)$ channel exhibits a state that is consistent with either a bound state or a scattering state close to threshold. These results are in agreement with the previous conclusions of the NPLQCD collaboration regarding the existence of two-nucleon bound states at this value of the quark masses.