Standard Model $H\rightarrow ZZ^{(*)}\rightarrow \ell\ell\ell\ell$, $\ell\ell\nu\nu$, $\ell\ell qq$ Searches with ATLAS at the LHC

TL;DR

This paper reports on the ATLAS experiment's search for the Standard Model Higgs boson decaying into Z boson pairs across three final states, excluding certain mass ranges with data from the 2011 LHC run.

Contribution

First comprehensive search for Higgs decays to ZZ in multiple final states using early LHC data, setting new exclusion limits in specific mass ranges.

Findings

Excluded Higgs mass ranges: 192-196 GeV, 214-222 GeV, 340-460 GeV.

Analyzed over 1 fb$^{-1}$ of proton-proton collision data.

Used three decay channels to improve search sensitivity.

Abstract

The latest results on the direct experimental search for a Standard Model Higgs boson decaying to a pair of Z bosons are presented. Three distinct final states are considered: $H\rightarrow ZZ^{(*)}\rightarrow \ell\ell\ell\ell$, $H\rightarrow ZZ\rightarrow \ell\ell\nu\nu$, and $H\rightarrow ZZ\rightarrow \ell\ell qq$, where $\ell = e, \mu$. A dataset of more than 1fb$^{-1}$ of proton-proton collisions at $\sqrt{s} = 7$ TeV collected by the ATLAS detector at the CERN LHC during the on-going 2011 run is used. In this model and for these final states, Higgs boson masses in the ranges 192 GeV $< m_H < $ 196 GeV, 214 $ < m_H < $ 222 GeV, and 340 $< m_H < $ 460 GeV have been excluded at the 95% confidence level.