Adler Function, Sum Rules and Crewther Relation of Order O(alpha_s^4): the Singlet Case

TL;DR

This paper presents a five-loop calculation of the singlet part of the Adler function in a general gauge theory, confirming the generalized Crewther relation at order alpha_s^4 and providing a complete correction for e+e- annihilation into hadrons.

Contribution

It provides the first five-loop analytic result for the singlet Adler function and verifies the generalized Crewther relation at this order.

Findings

Validated the generalized Crewther relation for the singlet case.

Derived the complete ${ m O}(\a_s^4)$ correction to the Adler function.

Produced the full ${ m O}(\a_s^4)$ correction for e+e- annihilation into hadrons.

Abstract

The analytic result for the singlet part of the Adler function of the vector current in a general gauge theory is presented in five-loop approximation. Comparing this result with the corresponding singlet part of the Gross-Llewellyn Smith sum rule [1], we successfully demonstrate the validity of the generalized Crewther relation for the singlet part. This provides a non-trivial test of both our calculations and the generalized Crewther relation. Combining the result with the already available non-singlet part of the Adler function [2,3] we arrive at the complete ${\cal O}(\alpha_s^4)$ expression for the Adler function and, as a direct consequence, at the complete ${\cal O}(\alpha_s^4)$ correction to the $e^+ e^-$ annihilation into hadrons in a general gauge theory.