Search for dark photons from Higgs boson decays via $ZH$ production with a photon plus missing transverse momentum signature from $pp$ collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector

Abstract

This paper describes a search for dark photons (${\gamma }_d$) in proton-proton collisions at $\sqrt{s}=13$ TeV at the Large Hadron Collider (LHC). The dark photons are searched for in the decay of Higgs bosons ($H\to \gamma {\gamma }_d$) produced through the $ZH$ production mode. The transverse mass of the system, made of the photon and the missing transverse momentum from the non-interacting ${\gamma }_d$, presents a distinctive signature as it peaks near the Higgs boson mass. The results presented use the total Run-2 integrated luminosity of 139 fb${}^{-1}$ recorded by the ATLAS detector at the LHC. The dominant reducible background processes are estimated using data-driven techniques. A Boosted Decision Tree technique is adopted to enhance the sensitivity of the search. As no excess is observed with respect to the Standard Model prediction, an observed (expected) upper limit on the branching ratio BR$(H\to \gamma {\gamma }_d)$ of 2.28$\%$ (2.82${}_{-0.84}^{+1.33}\%$) is set at 95$\%$ CL for massless ${\gamma }_d$. For massive dark photons up to 40 GeV, the observed (expected) upper limits on BR$(H\to \gamma {\gamma }_d)$ at 95\% confidence level is found within the [2.19,2.52]$\%$ ([2.71,3.11]$\%$) range.

arXiv comment48 pages, author list starting page 31, 14 figures, 10 tables, published in JHEP. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HDBS-2019-13

References in corpus (36)

• XGBoost: A Scalable Tree Boosting System
• The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
• The anti-k_t jet clustering algorithm
• An Introduction to PYTHIA 8.2
• A Brief Introduction to PYTHIA 8.1
• FastJet user manual
• New Generation of Parton Distributions with Uncertainties from Global QCD Analysis
• Asymptotic formulae for likelihood-based tests of new physics
• Parton distributions for the LHC Run II
• A direct empirical proof of the existence of dark matter
• Event generation with SHERPA 1.1
• A Theory of Dark Matter
• Scattering Amplitudes with Open Loops
• A parton shower algorithm based on Catani-Seymour dipole factorisation
• Comix, a new matrix element generator
• Event Generation with Sherpa 2.2
• QCD matrix elements + parton showers: The NLO case
• Single-top hadroproduction in association with a W boson
• Electroweak gauge boson production at hadron colliders through O(alpha_s^2)
• Isolated photons in perturbative QCD
• Illuminating Dark Photons with High-Energy Colliders
• The Dark Photon
• HistFitter software framework for statistical data analysis
• Matching Tree-Level Matrix Elements with Interleaved Showers
• HW/HZ + 0 and 1 jet at NLO with the POWHEG BOX interfaced to GoSam and their merging within MiNLO
• LHC probes the hidden sector
• A Dark-Disk Universe
• NLO Higgs boson production plus one and two jets using the POWHEG BOX, MadGraph4 and MCFM
• Operation of the ATLAS trigger system in Run 2
• Visible Effects of Invisible Hidden Valley Radiation
• The Higgs Boson Lineshape
• Proton Fixed-Target Scintillation Experiment to Search for Minicharged Particles
• Dark photons and resonant monophoton signatures in Higgs boson decays at the LHC
• Exponentially spread dynamical Yukawa couplings from non-perturbative chiral symmetry breaking in the dark sector
• Dark-Photon searches via Higgs-boson production at the LHC
• Recent Progress in Search for Dark Sector Signatures

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