α_s from an improved τ vector isovector spectral function

¹ Instituto de Física de São Carlos, Universidade de São Paulo, CP 369, 13570-970, São Carlos, SP, Brazil
² Department of Physics and Astronomy, San Francisco State University, San Francisco, CA 94132, USA
³ Department of Mathematics and Statistics, York University Toronto, ON Canada M3J 1P3
⁴ Department of Physics and IFAE-BIST, Universitat Autònoma de Barcelona E-08193 Bellaterra, Barcelona, Spain
⁵ Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, 22607 Hamburg, Germany
⁶ Department of Physics, University of Washington, Seattle, WA 98195-1560, USA

^* peris@ifae.es

Published online: 22 December 2022

Abstract

After discussing difficulties in determining α_s from tau decay due to the existence of Duality Violations and the associated asymptotic nature of the OPE, we describe a new determination based on an improved vector isovector spectral function, now based solely on experimental input, obtained by (i) combining ALEPH and OPAL results for 2π + 4π and (ii) replacing K⁻K⁰ and higher-multiplicity exclusive-mode contributions, both previously estimated using Monte Carlo, with new experimental BaBar results for K⁻K⁰ and results implied by e⁺e⁻ cross sections and CVC for the higher-multiplicity modes. We find α_s(m_τ) = 0.3077±0.0075, which corresponds to α_s(m_Z) = 0.1171±0.0010. Finally, we comment on some of the shortcomings in the criticism of our approach by Pich and Rodriguez-Sanchez.