Semileptonic Hyperon Decays and CKM Unitarity

Abstract

Using a technique that is not subject to first-order SU(3) symmetry breaking effects, we determine the $V_{us}$ element of the CKM matrix from data on semileptonic hyperon decays. We obtain $V_{us}$ =0.2250(27). This value is of similar precision to the one derived from $K_{l3}$, but higher and in better agreement with the unitarity requirement, $|V_{ud}{|}^2+|V_{us}{|}^2+|V_{ub}{|}^2=1$.

Comments: 3 pages, 1 table