Hyperon couplings from $N_f=2+1$ lattice QCD

Abstract

We compute various (generalized) isovector charges of the octet baryons. These include $g_A$, $g_T$ and $g_S$ as well as the unpolarized, polarized and transversity parton distribution function (PDF) momentum fractions $⟨x{⟩}_{u^{+}-d^{+}}$, $⟨x{⟩}_{\Delta u^{-}-\Delta d^{-}}$ and $⟨x{⟩}_{\delta u^{+}-{\delta }^{+}}$. The simulations are carried out on a subset of the (isospin symmetric) $N_f=2+1$ flavour Coordinated Lattice Simulations (CLS) gauge ensembles with lattice spacings ranging from $a\approx 0.086$fm down to $a\approx 0.050$fm. First results on the breaking of flavour symmetry and the low energy constants $F$ and $D$ are presented. While SU(3) flavour symmetry violations are found to be sizeable for $g_A=⟨1{⟩}_{\Delta u^{+}-\Delta d^{+}}$, these are quite small for $g_T=⟨1{⟩}_{\delta u^{-}-\delta d^{-}}$ and $⟨x{⟩}_{u^{+}-d^{+}}$.

Comments: 7 pages, 5 figures, talk given at Lattice 2019, v2: corrected some typos