Search for dark matter produced in association with a Higgs boson decaying to two bottom quarks in $pp$ collisions at $\sqrt{s} = 8$ TeV with the ATLAS detector

TL;DR

This paper reports a search for dark matter produced alongside a Higgs boson decaying to bottom quarks in proton-proton collisions at 8 TeV, setting limits on new physics models involving dark matter and Higgs interactions.

Contribution

It introduces a novel search strategy for dark matter in association with Higgs bosons decaying to bottom quarks using ATLAS data at 8 TeV, and interprets results within simplified and effective field theory models.

Findings

No significant excess over Standard Model backgrounds.

Set upper limits on cross-sections for Higgs plus missing energy events.

Excluded certain parameter regions in dark matter models.

Abstract

This article reports on a search for dark matter pair production in association with a Higgs boson decaying to a pair of bottom quarks, using data from $20.3 fb^{-1}$ of $pp$ collisions at a center-of-mass energy of 8 TeV collected by the ATLAS detector at the LHC. The decay of the Higgs boson is reconstructed as a high-momentum $b\bar{b}$ system with either a pair of small-radius jets, or a single large-radius jet with substructure. The observed data are found to be consistent with the expected Standard Model backgrounds. Model-independent upper limits are placed on the visible cross-sections for events with a Higgs boson decaying into $b\bar{b}$ and large missing transverse momentum with thresholds ranging from 150 GeV to 400 GeV. Results are interpreted using a simplified model with a $Z^\prime$ gauge boson decaying into different Higgs bosons predicted in a two-Higgs-doublet model, of which the heavy pseudoscalar Higgs decays into a pair of dark matter particles. Exclusion limits are also presented for the mass scales of various effective field theory operators that describe the interaction between dark matter particles and the Higgs boson.