Polarizabilities from kaon Compton scattering

TL;DR

This paper proposes a dispersion theory-based method to extract kaon polarizabilities from Compton scattering data, accounting for the nearby $K^*(892)$ resonance, and discusses the potential to distinguish electric and magnetic polarizabilities.

Contribution

It introduces a model-independent approach to include the $K^*(892)$ resonance in kaon polarizability measurements using dispersion theory.

Findings

The method extends the energy range for kaon polarizability extraction.

There is likely no strong hierarchy between electric and magnetic polarizabilities for kaons.

Improved angular coverage can help disentangle the polarizabilities.

Abstract

The polarizabilities of light pseudoscalar mesons can be extracted from differential cross sections for Compton scattering near threshold. While this has been accomplished for charged pions employing Primakoff reactions, a corresponding measurement for kaons will be affected by the presence of the $K^*(892)$ resonance not too far from threshold. We propose a method to extend the energy range serviceable for this purpose by reconstructing the $K^*(892)$ contribution model-independently from its $K\pi$ intermediate state, using dispersion theory. We point out that, in contrast to the charged-pion analog, there is likely no strong hierarchy between sum and difference of electric and magnetic dipole polarizabilities; we discuss the sensitivity to disentangling both by improved experimental angular coverage.