Chiral Perturbation Theory and Mesons

TL;DR

This paper reviews recent advances in mesonic Chiral Perturbation Theory, including data fits, extensions like hard pion ChPT, two-loop EFT developments, and high-order calculations in nonlinear sigma models.

Contribution

It summarizes recent progress across four areas in mesonic ChPT, highlighting new data fits, theoretical extensions, and complex calculations.

Findings

Updated fit of low-energy constants to experimental data

Development of hard pion ChPT methodology

Two-loop calculations for EFT in QCD-like theories

Abstract

The talk contains a short introduction to mesonic Chiral Perturbation Theory (ChPT). In addition four disparate areas where some progress has been made in recent years are discussed. These are the last fit of the order $p^4$ low-energy-constants $L_i^r$ to data, hard pion ChPT, the recent two-loop work on EFT for QCD like theories and the high order leading logarithm calculations in the massive $O(N)$ nonlinear sigma model.