Dipole and quadrupole polarizabilities of the pion

TL;DR

This paper reviews experimental data on pion polarizabilities, compares them with theoretical predictions from dispersion sum rules and chiral perturbation theory, and discusses discrepancies between these models.

Contribution

It provides a comprehensive comparison of experimental results with theoretical models for pion polarizabilities and explores reasons for their differences.

Findings

Experimental values of pion polarizabilities are summarized.

Discrepancies between DSR and ChPT predictions are analyzed.

Possible reasons for differences between models are discussed.

Abstract

Data on pion polarizabilities obtained in different experiments are reviewed. The values of the dipole and quadrupole polarizabilities of the pi^0 and pi^{+-} mesons found are compared with predictions of dispersion sum rules (DSRs) and two-loop calculations in the framework of chiral perturbation theory (ChPT). Possible reasons of a difference between the predictions of DSRs and ChPT are discussed.