Structure functions of 2d integrable asymptotically free models

TL;DR

This paper studies the structure functions of 2D integrable asymptotically free models using the S-matrix bootstrap, revealing universal small-x behavior and providing accurate computations for the O(3) model across a wide range.

Contribution

It presents the exact small-x behavior of structure functions in 2D integrable models and demonstrates their universality, with detailed calculations for the O(3) model and comparisons to perturbation theory.

Findings

Universal small-x behavior in 2D models

Accurate computation of structure functions for O(3) model

Comparison with perturbative results

Abstract

We investigate structure functions in the 2--dimensional (asymptotically free) non--linear O$(n) \sigma$--models using the non--perturbative S--matrix bootstrap program. In particular the {\it exact small (Bjorken) $x$ behavior is exhibited}; the structure is rather universal and is probably the same in a wide class of (integrable) asymptotically free models. Structurally similar universal formulae may also hold for the small $x$ behavior of QCD in 4--dimensions. Structure functions in the special case of the $n=3$ model are accurately computed over the whole $x$ range for $-q^2/M^2<10^5$, and some moments are compared with results from renormalized perturbation theory. Some remarks concerning the structure functions in the $1/n$ approximation are also made.