# Stealth multiboson signals

## TL;DR

This paper introduces 'stealth bosons', light boosted particles that decay into four quarks reconstructed as single jets, which evade standard detection methods and could explain small excesses in diboson resonance searches around 2 TeV.

## Contribution

The paper proposes a new class of particles called stealth bosons that mimic QCD jets, challenging existing search strategies and potentially explaining observed anomalies.

## Key findings

- Stealth bosons produce jets that appear QCD-like in standard substructure variables.
- These jets often have higher track multiplicity than typical W/Z jets.
- Heavy resonances decaying into stealth bosons could account for small excesses near 2 TeV.

## Abstract

We introduce the `stealth bosons' $S$, light boosted particles with a decay $S \to AA \to q \bar q q \bar q$ into two daughter bosons $A$, which subsequently decay into four quarks that are reconstructed as a single fat jet. Variables that measure the two-pronged structure of fat jets, which are used for diboson resonance searches in hadronic or semi-leptonic final states, classify the jets produced in stealth boson decays as QCD-like - actually, for these variables they may seem more background-like than the QCD background itself. The number of tracks in those jets can also be, on average, much higher than for the fat jets arising from the hadronic decay of boosted $W$ and $Z$ bosons. Therefore, these elusive particles are hard to spot in standard searches. Heavy resonances decaying into two such stealth bosons, or one plus a $W/Z$ boson, could offer an explanation for the recurrent small excesses found in hadronic diboson resonance searches near an invariant mass of 2 TeV.