SU(3) breaking in hyperon transition vector form factors

TL;DR

This paper calculates SU(3)-breaking effects in hyperon transition vector form factors using chiral perturbation theory, constrained by lattice QCD, to improve the precision of |V_{us}| from hyperon decays.

Contribution

It provides a next-to-leading order calculation of SU(3) breaking in hyperon form factors including decuplet states, constrained by lattice QCD data.

Findings

Determined lattice-informed values of the form factor f_1 at the physical point.

Progressed towards precise |V_{us}| extraction from hyperon semileptonic decays.

Extended chiral perturbation theory calculations to include SU(3) breaking effects.

Abstract

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 regularisation. 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 $\Sigma^-\rightarrow n$ and $\Xi^0\rightarrow \Sigma^+$ transition form factors. Hence we determine lattice-informed values of $f_1$ at the physical point. This work constitutes progress towards the precise determination of $|V_{us}|$ from hyperon semileptonic decays.