Polarized Deep Inelastic Scattering Off the "Neutron" From Gauge/String Duality

TL;DR

This paper uses gauge/string duality to compute polarized deep inelastic scattering structure functions of a theoretical 'neutron', revealing suppression patterns and sum rule violations due to Pauli interactions, advancing understanding of holographic QCD models.

Contribution

It introduces a Pauli interaction term in AdS space to calculate neutron structure functions, showing suppression and sum rule breaking, which extends previous proton-focused holographic studies.

Findings

Neutron structure functions are power suppressed compared to proton.

The Burkhardt-Cottingham sum rule is broken by the Pauli interaction.

Pauli interaction naturally arises from higher-dimensional fermion-graviton couplings.

Abstract

We investigate deep inelastic scattering off the polarized "neutron" using gauge/string duality. The "neutron" corresponds to a supergravity mode of the neutral dilatino. Through introducing the Pauli interaction term into the action in $\textrm{AdS}_{5}$ space, we calculate the polarized deep inelastic structure functions of the "neutron" in supergravity approximation at large t' Hooft coupling $\lambda$ and finite $x$ with $\lambda^{-1/2}\ll x<1$. In comparison with the charged dilatino "proton," which has been obtained in the previous work by Gao and Xiao, we find the structure functions of the "neutron" are power suppressed at the same order as the ones of the "proton." Especially, we find the Burkhardt-Cottingham-like sum rule, which is satisfied in the work by Gao and Xiao, is broken due to the Pauli interaction term. We also illustrate how such a Pauli interaction term can arise naturally from higher dimensional fermion-graviton coupling through the usual Kaluza-Klein reduction.