Deep inelastic scattering from polarized spin-$1/2$ hadrons at low $x$ from string theory

TL;DR

This paper uses gauge/string duality to analyze polarized deep inelastic scattering of spin-1/2 hadrons at low Bjorken-x, calculating structure functions and comparing results with experimental data, especially in the Regge regime.

Contribution

It introduces a holographic approach to compute polarized structure functions at low x, incorporating string theory amplitudes and Regge physics, with detailed analysis of the Pomeron exchange.

Findings

Good agreement with experimental proton $g_1$ data

Holographic dual captures Regge physics at low x

Structure functions derived from string amplitudes

Abstract

We study polarized deep inelastic scattering of charged leptons from spin-$1/2$ hadrons at low values of the Bjorken parameter and large 't Hooft coupling in terms of the gauge/string theory duality. We calculate the structure functions from type IIB superstring theory scattering amplitudes. We discuss the role of the non-Abelian Chern-Simons term and the Pauli term from the five-dimensional $SU(4)$ gauged supergravity. Furthermore, the exponentially small-$x$ regime where Regge physics becomes important is analyzed in detail for the antisymmetric structure functions. In this case the holographic dual picture of the Pomeron exchange is realized by a Reggeized gauge field. We compare our results with experimental data of the proton antisymmetric structure function $g_1$, obtaining a very good level of agreement.