31 research outputs found

    The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe

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    The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay --- these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions. LBNE is conceived around three central components: (1) a new, high-intensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a near neutrino detector just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is approximately 1,300 km from the neutrino source at Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions. With its exceptional combination of experimental configuration, technical capabilities, and potential for transformative discoveries, LBNE promises to be a vital facility for the field of particle physics worldwide, providing physicists from around the globe with opportunities to collaborate in a twenty to thirty year program of exciting science. In this document we provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess.Comment: Major update of previous version. This is the reference document for LBNE science program and current status. Chapters 1, 3, and 9 provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess. 288 pages, 116 figure

    A search for the Higgs boson and a search for dark-matter particle with jets and missing transverse energy at collider detector at Fermilab

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    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