|V_us| determination from inclusive strange tau decay and lattice HVP

¹ SUPA, School of Physics, The University of Edinburgh, Edinburgh EH9 3JZ, UK
² York University, 4700 Keele St., Toronto, ON Canada M3J IP3
³ Physics Department, Brookhaven National Laboratory, Upton, NY 11973, USA
⁴ RIKEN-BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973, USA
⁵ School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, UK
⁶ CSSM, University of Adelaide, Adelaide, SA 5005 Australia
⁷ Physics Department, Nara Womens University, Nara 630-8506, Japan
⁸ School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ, UK

Published online: 26 March 2018

Abstract

We propose and apply a novel approach to determining |V_us| which uses inclusive strange hadronic tau decay data and hadronic vacuum polarization functions (HVPs) computed on the lattice. The experimental and lattice data are related through dispersion relations which employ a class of weight functions having poles at space-like momentum. Implementing this approach using lattice data generated by the RBC/UKQCD collaboration, we show examples of weight functions which strongly suppress spectral integral contributions from the region where experimental data either have large uncertainties or do not exist while at the same time allowing accurate determinations of relevant lattice HVPs. Our result for |V_us| is in good agreement with determinations from K physics and 3-family CKM unitarity. The advantages of the new approach over the conventional sum rule analysis will be discussed.