The universal expression for the amplitude square in quantum electrodynamics

TL;DR

This paper derives a universal, covariant expression for the squared amplitude in quantum electrodynamics, simplifying calculations of cross-sections for various processes involving polarized and unpolarized particles.

Contribution

It introduces a universal formula for the amplitude square in QED that streamlines calculations and avoids complex Dirac matrix trace computations.

Findings

Provides a covariant, universal expression for amplitude squares in QED.

Simplifies cross-section calculations for different processes.

Facilitates calculations involving polarized and unpolarized particles.

Abstract

The universal expression for the amplitude square |u_f M u_i|^2 for any matrix of interaction M is derived. It has obvious covariant form. It allows the avoidance of calculation of products of the Dirac's matrices traces and allows easy calculation of cross-sections of any different processes with polarized and unpolarized particles.