Pion wave functions from holographic QCD and the role of infrared renormalons in photon-photon collisions

TL;DR

This paper investigates the impact of higher-twist effects on pion production in photon-photon collisions using holographic QCD, comparing running and frozen coupling approaches and highlighting the role of infrared renormalons.

Contribution

It introduces a detailed calculation of higher-twist contributions in photon-photon collisions within holographic QCD, contrasting different coupling approaches and linking results to the pion electromagnetic form factor.

Findings

Resummed higher-twist cross sections differ from frozen coupling results.

Higher-twist effects are normalized by the pion electromagnetic form factor.

Frozen coupling approach provides a consistent normalization scheme.

Abstract

In this article, we calculate the contribution of the higher-twist Feynman diagrams to the large-$p_T$ inclusive single pion production cross section in photon-photon collisions in case of the running coupling and frozen coupling approaches within holographic QCD. We compare the resummed higher-twist cross sections with the ones obtained in the framework of the frozen coupling approach and leading-twist cross section. Also, we show that in the context of frozen coupling approach a higher-twist contribution to the photon-photon collisions cross section is normalized in terms of the pion electromagnetic form factor.