SANC: the process $ \gamma \gamma \rightarrow ZZ $

TL;DR

This paper presents a detailed one-loop level implementation of the gamma gamma to ZZ process within the SANC system, providing analytical results, validation checks, and comparisons with existing literature.

Contribution

It introduces a comprehensive one-loop calculation of gamma gamma to ZZ in SANC, including scalar form factors, analytical expressions, and validation methods.

Findings

Scalar form factors are gauge-independent.

Analytical and numerical results are consistent with literature.

Helicity amplitudes are explicitly derived.

Abstract

The implementation of the process $\gamma\gamma \to ZZ$ at the one-loop level within {\tt SANC} system multi-channel approach is considered. The derived one-loop scalar form factors can be used for any cross channel after an appropriate permutation of their arguments -- Mandelstam variables $s,t,u$. To check of the correctness of the results we observe the independence of the scalar form factors on the gauge parameters and the validity of Ward identity (external photon transversality). We present the complete analytical results for the covariant and tensor structures and helicity amplitudes for this process. We make an extensive comparison of our analytical and numerical results with those existing in the literature.