# Leptons lurking in semi-visible jets at the LHC

**Authors:** Cesare Cazzaniga, Annapaola de Cosa  
**arXiv:** [2206.03909](https://arxiv.org/abs/2206.03909)  
**Date:** 2022-06-08  
**Summary page:** https://www.summarizepaper.com/en/arxiv-id/2206.03909v3/

## Key points

- Cazzaniga and de Cosa propose a novel search strategy at the Large Hadron Collider (LHC) for detecting hidden sectors that may contain dark matter.
- The focus is on semi-visible jets, which are hadronic jets potentially containing stable invisible bound states of dark matter particles.
- A simplified model involving two messenger fields with a significant mass gap is introduced to allow for the decay of dark bound states into pairs of oppositely charged leptons within the semi-visible jets.
- The experimental signature involves non-isolated lepton pairs inside these jets, aiming to be independent of specific model assumptions and target this new signature within LHC data.
- With full Run 2 data from LHC, the search could provide 3σ evidence or exclusion of heavier mediators up to masses of 3.5 TeV or 4.5 TeV respectively.
- By exploiting resonant features in lepton pairs, sensitivity reach can be enhanced for specific models, potentially leading to a 5σ discovery up to masses of 3.5 TeV and improved exclusion beyond 5 TeV.
- This study presents an innovative approach to exploring confining dark sectors through semi-visible jets with non-isolated prompt lepton pairs at LHC, offering promising prospects for uncovering new physics phenomena and expanding our understanding of fundamental particles and interactions in high-energy collisions.

## Summary

In this study, Cazzaniga and de Cosa propose a novel search strategy at the Large Hadron Collider (LHC) for detecting hidden sectors that may contain dark matter. The authors focus on the concept of semi-visible jets, which are hadronic jets that could potentially contain stable invisible bound states of dark matter particles. These semi-visible jets have been previously studied in fully hadronic signatures, where the composite dark matter decays promptly back to Standard Model quarks. To investigate this phenomenon further, the authors introduce a simplified model involving two messenger fields with a significant mass gap. This setup allows for the decay of dark bound states into pairs of oppositely charged leptons within the semi-visible jets. The experimental signature of interest is characterized by non-isolated lepton pairs inside these jets. The proposed search strategy is designed to be independent of specific model assumptions and aims to target this new signature within LHC data. By remaining agnostic about the shape of the di-lepton spectrum, the authors determine the sensitivity of their analysis to detect the target signal. They predict that with full Run 2 data from LHC, this search could provide 3σ evidence or exclusion of heavier mediators up to masses of 3.5 TeV or 4.5 TeV respectively. Furthermore, by exploiting resonant features in lepton pairs, it is suggested that sensitivity reach can be enhanced for specific models. An analysis utilizing di-lepton invariant mass information has potential for a 5σ discovery up to masses of 3.5 TeV and improved exclusion beyond 5 TeV. Overall, this study presents an innovative approach to exploring confining dark sectors through semi-visible jets with non-isolated prompt lepton pairs at LHC. The proposed search strategy offers promising prospects for uncovering new physics phenomena and expanding our understanding of fundamental particles and interactions in high-energy collisions.