Probing compressed dark sectors at 100 TeV in the dileptonic mono-Z channel

TL;DR

This paper investigates the potential to detect compressed dark sectors at a future 100 TeV collider using the mono-Z channel with leptonic decays, demonstrating the ability to exclude certain electroweak multiplets with high luminosity.

Contribution

It introduces a detailed analysis of the mono-Z channel for probing compressed dark sectors at 100 TeV, including background estimation and sensitivity projections.

Findings

Excludes TeV-scale compressed dark sectors with 30 ab$^{-1}$ luminosity.

Can exclude pure higgsino at 500 GeV and wino at 970 GeV.

Achieves sensitivity with 1 ext% background systematic uncertainty.

Abstract

We examine the sensitivity at a future 100 TeV proton-proton collider to compressed dark sectors whose decay products are invisible due to below-threshold energies and/or small couplings to the Standard Model. This scenario could be relevant to models of WIMP dark matter, where the lightest New Physics state is an (isolated) electroweak multiplet whose lowest component is stable on cosmological timescales. We rely on the additional emission of a hard on-shell $Z$-boson decaying to leptons, a channel with low background systematics, and include a careful estimate of the real and fake backgrounds to this process in our analysis. We show that an integrated luminosity of 30 ab$^{-1}$ would allow exclusion of a TeV-scale compressed dark sector with inclusive production cross section of 0.3 fb, for 1\% background systematic uncertainty and splittings below 5 GeV. This translates to exclusion of a pure higgsino (wino) multiplet with mass of 500 (970) GeV.