Predictions for all processes e^+e^- -> 4 fermions + gamma

TL;DR

This paper calculates complete matrix elements for e^+e^- collisions producing four fermions with or without an additional photon within the Standard Model, providing tools for precise simulations and analysis.

Contribution

It introduces a comprehensive calculation of matrix elements for all final states in e^+e^- -> 4f and 4f + gamma, including treatment of gauge boson widths and Monte Carlo generators.

Findings

Provides compact generic functions for matrix elements.

Includes a gauge-invariant scheme with complex gauge-boson masses.

Offers detailed numerical results for cross sections and photon distributions.

Abstract

The complete matrix elements for e^+ e^- -> 4f and e^+ e^- -> 4f + gamma are calculated in the Electroweak Standard Model for polarized massless fermions. The matrix elements for all final states are reduced to a few compact generic functions. Monte Carlo generators for e^+ e^- -> 4f and e^+ e^- -> 4f + gamma are constructed. We compare different treatments of the finite widths of the electroweak gauge bosons; in particular, we include a scheme with a complex gauge-boson mass that obeys all Ward identities. The detailed discussion of numerical results comprises integrated cross sections as well as photon-energy distributions for all different final states.