Virtual Compton Scattering off a Spinless Target in the AdS/QCD correspondence

TL;DR

This paper investigates doubly virtual Compton scattering off a spinless target using AdS/QCD, revealing limitations of the standard models in reproducing Lorentz and gauge invariance, and suggests experimental tests to challenge minimal AdS/QCD predictions.

Contribution

It analyzes the structure of Compton scattering within AdS/QCD and highlights discrepancies with fundamental symmetries, proposing experimental polarizability measurements as tests.

Findings

Standard AdS/QCD struggles with Lorentz and gauge invariance in this context.

Real Compton scattering measurements can test AdS/QCD predictions.

Minimal AdS/QCD may be inconsistent with observed polarizabilities.

Abstract

We perform a study of the doubly virtual Compton scattering off a spinless target gamma* P -> 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, and presumably exclude results based on the AdS/QCD correspondence in its minimal version.