Low-energy constants from ALEPH hadronic tau decay data

TL;DR

This paper extracts precise values of low-energy constants in chiral perturbation theory using updated experimental tau decay data and lattice QCD results, achieving high accuracy at NNLO order.

Contribution

It provides the first comprehensive determination of multiple NNLO chiral low-energy constants combining experimental and lattice data.

Findings

Determined $L_{10}$ and other NNLO constants with errors at or below higher-order contributions.

Achieved a level of precision that exhausts the meaningful potential of NNLO analysis.

Demonstrated consistency between tau decay data and lattice QCD results.

Abstract

We determined the NLO chiral low-energy constant $L_{10}$, and various combinations of NNLO chiral low-energy constants employing recently revised ALEPH results for the non-strange vector (V) and axial-vector (A) hadronic tau decay distributions and recently updated RBC/UKQCD lattice data for the non-strange V-A two-point function. In this talk, we explain the ingredients of this determination. Our errors are at or below the level expected for contributions of yet higher order in the chiral expansion, suggesting that our results exhaust the possibilities of what can be meaningfully achieved in an NNLO analysis.