Precision phenomenology at multi-TeV muon colliders

TL;DR

This paper enhances electroweak predictions for multi-TeV muon colliders by including higher-order QED and weak effects, enabling percent-level precision for various observables in high-energy lepton collisions.

Contribution

It introduces a comprehensive framework for next-to-leading order electroweak calculations that incorporate higher-order effects and all-order QED resummation for muon colliders.

Findings

Predictions achieve percent-level accuracy for $t\bar{t}$ and $W^+W^-$ production.

Inclusion of higher-order electroweak effects improves theoretical precision.

Framework applicable to arbitrary observables and phase space regions.

Abstract

Future lepton colliders, such as those based on linear $e^+e^-$ or circular $\mu^+\mu^-$ accelerators, are expected to attain centre-of-mass energies in the multi-TeV range. In this regime the impact of QED and of weak radiation, in both the initial and the final state, can become a leading effect. By employing a general framework presented in a companion paper - suitable for any flavour of colliding leptons - we improve next-to-leading order electroweak predictions by including higher-order contributions, which encompass, but are not limited to, vector-boson-fusion processes. We apply this approach to the study of $t\bar{t}$ and $W^+W^-$ production at a muon collider operating at centre-of-mass energies up to 10 TeV. We show that such an approach, where both QED and weak contributions are included at fixed order, in addition to the all-order resummation of initial-state QED effects, can provide predictions for arbitrary observables in all of the phase space which are precise at the percent level.