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

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 $langle xrangle_{u^+-d^+}$, $langle xrangle_{Delta u^--Delta d^-}$ and $langle xrangle_{delta u^+-delta ^+}$. 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 $aapprox 0.086,$fm down to $aapprox 0.050,$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 $g_A=langle 1rangle_{Delta u^+-Delta d^+}$, these are quite small for $g_T=langle 1rangle_{delta u^--delta d^-}$ and $langle xrangle_{u^+-d^+}$.