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Full-Text Articles in Physical Sciences and Mathematics

Search For Long-Lived, Weakly Interacting Particles That Decay To Displaced Hadronic Jets In Proton-Proton Collisions At √S = 8 Tev With The Atlas Detector, Preema R. Pais Nov 2016

Search For Long-Lived, Weakly Interacting Particles That Decay To Displaced Hadronic Jets In Proton-Proton Collisions At √S = 8 Tev With The Atlas Detector, Preema R. Pais

Doctoral Dissertations

Many new physics models predict the existence of neutral, weakly interacting, long-lived particles that can decay within the detector volume, producing a distinctive experimental signature. A search is performed for a pair of such particles, using proton-proton collision data at √s = 8 TeV collected by the ATLAS detector in 2012, corresponding to a total integrated luminosity of 20.3 fb-1. Novel techniques are developed for the reconstruction of displaced decays to hadronic jets in the inner tracking detector and muon spectrometer. No significant deviation is found from the number of background events expected from Standard Model processes. The …


Observation Of J/Psi P Resonances Consistent With Pentaquark States In Lambda_B^0 To J/Psi K^- P Decays, Nathan Philip Jurik Aug 2016

Observation Of J/Psi P Resonances Consistent With Pentaquark States In Lambda_B^0 To J/Psi K^- P Decays, Nathan Philip Jurik

Dissertations - ALL

The observation of structures consistent with charmonium-pentaquark states decaying to $J/\psi p$ in $\Lambda_b^0 \rightarrow J/\psi K^- p$ decays is presented. The data sample analyzed corresponds to an integrated luminosity of 3 $fb^{-1}$ acquired with the LHCb detector from 7 and 8 TeV $pp$ collisions. An amplitude analysis was performed which utilized all six kinematic degrees of freedom in the decay. It was shown that adequate descriptions of the data are unattainable with only $K^- p$ resonances in the amplitude model. For satisfactory fits of the data, it was found to be necessary to include two $J/\psi p$ resonances, with …


Modeling The Sps Feedback And Feedforward Systems For Improved Performance, Jake Hargrove May 2016

Modeling The Sps Feedback And Feedforward Systems For Improved Performance, Jake Hargrove

Physics

The Super Proton Synchrotron (SPS) is the last link in the chain of accelerators providing protons to the Large Hadron Collider (LHC). The SPS is currently the limiting factor on the maximum number of protons and thus collisions in the LHC. The SPS upgrade is under way to expand the discovery potential of the LHC. The accelerating system — Radio Frequency (RF) — is being improved. Models of the SPS RF feedback systems were developed. These models could assist with design choices, evaluating the upgraded system performance, and anticipate limitations and issues.


Measurement Of Spin Correlations In Tt Production Using The Matrix Element Method In The Muon+Jets Final State In Pp Collisions At √S=8 Tev, M M. Baarmand, Vallary Bhopatkar, Marcus Hohlmann, H Kalakhety, D Noonan, Tuhin S. Roy, Francisco X. Yumiceva, Cms Collaboration Jan 2016

Measurement Of Spin Correlations In Tt Production Using The Matrix Element Method In The Muon+Jets Final State In Pp Collisions At √S=8 Tev, M M. Baarmand, Vallary Bhopatkar, Marcus Hohlmann, H Kalakhety, D Noonan, Tuhin S. Roy, Francisco X. Yumiceva, Cms Collaboration

Aerospace, Physics, and Space Science Faculty Publications

The consistency of the spin correlation strength in top quark pair production with the standard model (SM) prediction is tested in the muon+jets final state. The events are selected from pp collisions, collected by the CMS detector, at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 fb-1. The data are compared with the expectation for the spin correlation predicted by the SM and with the expectation of no correlation. Using a template fit method, the fraction of events that show SM spin correlations is measured to be 0.72±0.08(stat)+0.15-0.13(syst), representing the most precise measurement of this …


A Search For Pair Production Of New Light Bosons Decaying Into Muons, Vallary Bhopatkar, Marcus Hohlmann, H Kalakhety, D Mareskas-Palcek, Tuhin S. Roy, Francisco X. Yumiceva, Cms Collaboration Jan 2016

A Search For Pair Production Of New Light Bosons Decaying Into Muons, Vallary Bhopatkar, Marcus Hohlmann, H Kalakhety, D Mareskas-Palcek, Tuhin S. Roy, Francisco X. Yumiceva, Cms Collaboration

Aerospace, Physics, and Space Science Faculty Publications

A search for the pair production of new light bosons, each decaying into a pair of muons, is performed with the CMS experiment at the LHC, using a dataset corresponding to an integrated luminosity of 20.7 fb-1 collected in proton-proton collisions at center-of-mass energy of √s=8 TeV. No excess is observed in the data relative to standard model background expectation and a model independent upper limit on the product of the cross section, branching fraction, and acceptance is derived. The results are compared with two benchmark models, the first one in the context of the next-to-minimal supersymmetric standard model, and …