25 research outputs found

    Search for New Particles Decaying to Hadronic Jets in Proton-Proton Collision at s = 13 TeV

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    This thesis presents a search for new resonances decaying to pairs of jets in 37 fb−1 of proton-proton collision data produced by the Large Hadron Collider at a center-of-mass energy of 13 TeV. The data was collected in 2015 and 2016 by the ATLAS detector. A new resonance search algorithm - SWiFt - was used to reduce the uncertainty in the data-driven estimate of the unknown backgrounds. SWiFt was utilized in a model-independent search, and also to perform model-dependent searches for excited quarks (q∗) and heavy gauge bosons (W â€Č). No evidence for new phenomena was observed, so 95% confidence-level upper limits were calculated on the production rates of q∗ and Wâ€Č. Upper limits were also calculated for Gaussian models which represent first-order approximations for many theoretical models that predict new particles decaying to two jets.PHDPhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/146070/1/ksekhon_1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146070/2/ksekhon_2.pd

    Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

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    A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

    Search for single production of vector-like quarks decaying into Wb in pp collisions at s=8\sqrt{s} = 8 TeV with the ATLAS detector