Deep inelastic scattering from gauge string duality in the soft wall model

TL;DR

This paper explores deep inelastic scattering using gauge/string duality with a soft IR cutoff, leading to linear Regge trajectories, and compares results with previous hard cutoff models.

Contribution

It introduces a soft IR cutoff in the gauge/string duality framework to calculate structure functions, extending prior hard cutoff approaches and proposing a hybrid model for fermions.

Findings

Results agree with hard cutoff models in the deep inelastic limit

Linear Regge trajectories are achieved for mesons

Hybrid model effectively computes fermion structure functions

Abstract

Deep inelastic structure functions have been calculated by Polchinski and Strassler in gauge/string duality introducing a hard infrared (IR) cut off in AdS space. Here we investigate this problem using a soft IR cut off that leads to linear Regge trajectories for mesons. We calculate the structure functions for scalar particles in the large x regime where supergravity approximation holds and the small x regime where massive string states contribute. We also propose a hybrid model to calculate structure functions for fermions in the supergravity approximation. In the deep inelastic limit our results are in agreement with those obtained using a hard cut off.