A search for the Higgs boson and a search for dark-matter particle with jets and missing transverse energy at collider detector at Fermilab
Abstract
Finding the standard model Higgs boson and discovering beyond-standard model physics phenomena have been the most important goals for the high-energy physics in the last decades. In this thesis, we present two such searches. First is the search for the low mass standard model Higgs boson produced in association with a vector boson; second is the first search for a dark-matter candidate (D) produced in association with a top quark ( t) in particle colliders. We search in events with energetic jets and large missing transverse energy – a signature characterized by complicated backgrounds – in data collected by the CDF detector with proton-antiproton collisions at the center-of-mass energy of [special characters omitted]= 1.96 TeV. We discuss the techniques that have been developed for background modeling, for discriminating signal from background, and for reducing background resulting from detector effects. In the Higgs search, we report the 95% confidence level upper limits on the production cross section across masses of 90 to 150 GeV/c 2. The expected limits are improved by an average of 14% relative to the previous analysis. The Large Hadron Collider experiments reported a Higgs-like particle with mass of 125 GeV/c2 by studying the data collected in year 2011/12. At a Higgs boson mass of 125 GeV/c2, our observed (expected) limit is 3.06 (3.33) times the standard model prediction, corresponding to one of the most sensitive searches to date in this final state. In the dark matter search, we find the data are consistent with the standard model prediction, thus set 95% confidence level upper limits on the cross section of the process pp → t + D as a function of the mass of the dark-matter candidate. The upper limits are approximately 0.5 pb for a dark-matter particle with masses in the range of 0-150 GeV/c2.
Degree
Ph.D.
Advisors
Bortoletto, Purdue University.
Subject Area
Particle physics
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