Longitudinally polarized ZZ scattering at the Muon Collider

TL;DR

This study assesses the potential of future muon colliders to detect longitudinally polarized ZZ scattering, showing promising sensitivity and discovery prospects at 14 TeV and 6 TeV energies with high luminosity.

Contribution

It provides the first Monte Carlo sensitivity analysis of longitudinal ZZ scattering at muon colliders, highlighting their advantages over the LHC for probing electroweak symmetry breaking.

Findings

A 14 TeV muon collider can achieve 5 sigma discovery with 3000/fb.

A 6 TeV muon collider can surpass HL-LHC sensitivity with around 4000/fb.

Lepton isolation and detector granularity effects are significant at higher energies.

Abstract

Measuring longitudinally polarized vector boson scattering in, e.g., the ZZ channel is a promising way to investigate the unitarization scheme from the Higgs and possible new physics beyond the Standard Model. However, at the LHC, it demands the end of the HL-LHC lifetime luminosity, 3000/fb, and advanced data analysis technique to reach the discovery threshold due to its small production rates. Instead, there could be great potential for future colliders. In this paper, we perform a Monte Carlo study and examine the projected sensitivity of longitudinally polarized ZZ scattering at a TeV scale muon collider. We conduct studies at 14 TeV and 6 TeV muon colliders respectively and find that a 5 standard deviation discovery can be achieved at a 14 TeV muon collider, with 3000/fb of data collected. While a 6 TeV muon collider can already surpass HL-LHC, reaching 2 standard deviations with around 4000/fb of data. The effect from lepton isolation and detector granularity is also discussed, which may be more obvious at higher energy muon colliders, as the leptons from longitudinally polarized Z decays tend to be closer.