Hyperon Physics from Lattice QCD

The hyperons are extremely interesting because they provide an ideal system in which to study SU(3) flavor symmetry breaking by replacement of up or down quarks in nucleons by strange ones. Hyperon semileptonic decays provide an additional way of extracting the CKM matrix element Vus and offer unique opportunities to understand baryon structure and decay mechanisms. However, since hyperons decay in less than a nanosecond under weak interactions, their experimental study is not as easy as for the nucleons, and thus hyperon properties are not as well determined. Recent successes of lattice QCD in computing nucleon structure[1,2,3] provide assurance that lattice QCD can reliably predict the properties of hyperons as well. Knowledge of these properties can be very valuable in understanding hypernuclear physics, the physics of neutron stars and the structure of nucleons. In this proceeding, I review the latest progress on the hyperon spectroscopy, axial coupling constants, electric charge radii, magnetic moments and semileptonic decay form factors using a mixed action, in which the sea and valence fermions use different lattice actions. Lattice calculations of hyperon scattering lengths are not included in this proceeding; for more details, please see Ref. [4]. In our case, the sea fermions are 2+1 flavors of staggered fermions (in configuration ensembles generated by the MILC collaboration[5]), and the valence fermions are domain-wall fermions (DWF). The pion mass ranges from 300 to 700MeV in a lattice box of size