Virtual Compton Scattering off a Spinless Target in AdS/QCD

TL;DR

This paper investigates virtual Compton scattering on a spinless target using AdS/QCD, highlighting challenges in reproducing Lorentz and gauge invariance and proposing polarizability measurements as tests.

Contribution

It explores the application of AdS/QCD to doubly virtual Compton scattering and discusses the limitations of standard models in capturing Lorentz and gauge invariance.

Findings

Standard AdS/QCD recipes struggle to reproduce the Compton amplitude structure.

Polarizability measurements can serve as stringent tests for AdS/QCD models.

Soft-photon regime analysis provides insights into the applicability of semi-classical approximations.

Abstract

We study the doubly virtual Compton scattering off a spinless target $\gamma^*P\to\gamma^*P'$ within the Anti-de Sitter(AdS)/QCD formalism. We find that the general structure allowed by the Lorentz invariance and gauge invariance of the Compton amplitude is not easily reproduced with the standard recipes of the AdS/QCD correspondence. In the soft-photon regime, where the semi-classical approximation is supposed to apply best, we show that the measurements of the electric and magnetic polarizabilities of a target like the charged pion in real Compton scattering, can already serve as stringent tests.