We present a calculation of the SU(3)-breaking corrections to the hyperon transition vector form factors to $\mathcal{O}(p^4)$ in heavy-baryon chiral perturbation theory with finite-range regularization. Both octet and decuplet degrees of freedom are included. We formulate a chiral expansion at the kinematic point $Q^2=-(M_{B_1}-M_{B_2}{)}^2$, which can be conveniently accessed in lattice QCD. The two unknown low-energy constants at this point are constrained by lattice QCD simulation results for the ${\mathrm{\Sigma }}^{-}\to n$ and ${\mathrm{\Xi }}^0\to {\mathrm{\Sigma }}^{+}$ transition form factors. Hence, we determine lattice-informed values of $f_1$ at the physical point. This work constitutes progress toward the precise determination of $|V_{us}|$ from hyperon semileptonic decays.

• Received 29 August 2015

DOI:https://doi.org/10.1103/PhysRevD.92.074029