Search for the Decay of the Higgs Boson to Charm Quarks with the ATLAS Experiment

TL;DR

This paper reports a search for the Higgs boson decaying into charm quarks using ATLAS data, setting upper limits on the decay rate and employing charm-tagging techniques to identify the signal.

Contribution

It presents the first direct search for Higgs to charm quark decays in the ZH production mode at the LHC, using advanced charm-tagging algorithms.

Findings

Upper limit on cross section times branching ratio is 2.7 pb at 95% CL.

The Standard Model predicts a much lower decay rate of 26 fb.

No significant excess observed over the background.

Abstract

A direct search for the Standard Model Higgs boson decaying to a pair of charm quarks is presented. Associated production of the Higgs and $Z$ bosons, in the decay mode $ZH\rightarrow \ell^+ \ell^- c \bar{c}$ is studied. A dataset with an integrated luminosity of 36.1 fb$^{-1}$ of $pp$ collisions at $\sqrt{s}=13$ TeV recorded by the ATLAS experiment at the LHC is used. The $H\rightarrow c\bar{c}$ signature is identified using charm-tagging algorithms. The observed (expected) upper limit on $\sigma(pp \rightarrow ZH) \times \mathcal{B}(H \rightarrow c\bar{c})$ is 2.7 ($3.9^{+2.1}_{-1.1}$) pb at the 95% confidence level for a Higgs boson mass of 125 GeV, while the Standard Model value is 26 fb.