SU(3) breaking in hyperon transition vector form factors

Abstract

We present a calculation of the SU(3)-breaking corrections to the hyperon transition vector form factors to O(p⁴) 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 Q²=−(Mʙ₁−Mʙ₂)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 Σ−→n and Ξ⁰→Σ+ transition form factors. Hence, we determine lattice-informed values of f₁ at the physical point. This work constitutes progress toward the precise determination of |Vus| from hyperon semileptonic decays.