Search for production of dark matter in association with a Higgs boson decaying to bb with the ATLAS detector

Baca, Matthew (2018). Search for production of dark matter in association with a Higgs boson decaying to bb with the ATLAS detector. University of Birmingham. Ph.D.

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Using 3.2 fb^-1 of sqrt(s) =13TeV proton-proton data collected in 2015 with the ATLAS detector at the Large Hadron Collider, new limits were imposed on the associated production of Dark Matter with a 125GeV Higgs boson which decays into a pair of b-quarks. The final state of the signal is a pair of b-quark jets and large Missing Transverse Momentum attributed to the DM escaping the detector.

The dominant backgrounds were simulated. These were subject to selection requirements to increase signal to background ratio. Three regions were designated based on the number of leptons in the event. 0 lepton events made up the signal region. Events with 1 and 2 leptons were control regions. Similar selection requirements were applied to the control regions as in the signal region, in order to examine a similar phase space. A blinding region was established in the 0 lepton region over the mbb distribution to mask where a reconstructed 125GeV Higgs boson would appear. The control regions and the side bands in the signal region were then fit to the mbb data distribution. Unblinding of the signal region did not result in the discovery of the decay channel, but allowed limits to be imposed.

Type of Work: Thesis (Doctorates > Ph.D.)
Award Type: Doctorates > Ph.D.
Nikolopoulos, KonstantinosUNSPECIFIEDUNSPECIFIED
College/Faculty: Colleges (2008 onwards) > College of Engineering & Physical Sciences
School or Department: School of Physics and Astronomy
Funders: None/not applicable
Subjects: Q Science > QC Physics


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