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arXiv · 2607.00564

Isospin-breaking effects in inclusive hadronic $\tau$ data for the muon $(g-2)$ from first principles

Mattia Bruno·Taku Izubuchi·Christoph Lehner·Aaron S. Meyer·Julian Parrino·Xin-Yu Tuo
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Abstract

The knowledge of isospin-breaking effects in hadronic $\tau$ decays is required for a high-precision determination of the Hadronic-Vacuum-Polarization contribution to $(g-2)_\mu$ from experimental $\tau$ data. In this work we present a strategy for their calculation in a fully inclusive setup from first-principles Lattice QCD+QED simulations. We separate radiative corrections in three infrared safe classes, which we study individually. We provide analytic expressions for their effects in the initial state and propose a strategy for final-state corrections directly in Euclidean space. We also examine the non-factorizable contributions and highlight the challenges associated with their analytic continuation from Euclidean to Minkowski space. By studying short-distance corrections in the context of momentum schemes, we provide a prescription for the renormalization of the individual terms at first order in the ispospin-breaking parameters.

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Mattia Bruno, Taku Izubuchi, Christoph Lehner, Aaron S. Meyer, Julian Parrino, Xin-Yu Tuo. 2026-07-01. Isospin-breaking effects in inclusive hadronic $\tau$ data for the muon $(g-2)$ from first principles. https://arxiv.org/abs/2607.00564

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