A search for prompt lepton-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

TL;DR

This paper searches for light bosons decaying into collimated muons or electrons, called lepton-jets, using ATLAS data, but finds no evidence and sets exclusion limits on their production.

Contribution

First search for lepton-jets from light bosons in pp collisions at 7 TeV with ATLAS, establishing exclusion limits on their production cross section.

Findings

No significant deviation from the Standard Model.

Set 95% CL exclusion limits on light boson production.

Analyzed multiple lepton-jet signatures.

Abstract

We present a search for a light (mass < 2 GeV) boson predicted by Hidden Valley supersymmetric models that decays into a final state consisting of collimated muons or electrons, denoted "lepton-jets". The analysis uses 5fb-1 of sqrt(s) = 7 TeV proton--proton collision data recorded by the ATLAS detector at the Large Hadron Collider to search for the following signatures: single lepton-jets with at least four muons; pairs of lepton-jets, each with two or more muons; and pairs of lepton-jets with two or more electrons. This study finds no statistically significant deviation from the Standard Model prediction and places 95% confidence-level exclusion limits on the production cross section times branching ratio of light bosons for several parameter sets of a Hidden Valley model.