Precise Determination of |V{us}| from Lattice Calculations of Pseudoscalar Decay Constants
William J. Marciano
TL;DR
Comparing the ratio of experimental kaon and pion decay widths with a recent lattice gauge theory calculation provides a precise value for the Cabibbo-Kobayashi-Maskawa quark mixing matrix element, which is compared with other determinations of that fundamental parameter, implications, and an outlook for future improvements.
Abstract
Combining the ratio of experimental kaon and pion decay widths, Gamma(K to mu antineutrino{mu} (gamma)) / Gamma(pi to mu \antineutrino (gamma)), with a recent lattice gauge theory calculation of f{K}/f{pi} provides a precise value for the CKM quark mixing matrix element |V{us}|=0.2236(30) or if 3 generation unitarity is assumed |V{us}|=0.2238(30). Comparison with other determinations of that fundamental parameter, implications, and an outlook for future improvements are given.