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The Search for the Dark Matter Signature in the Lepton Jet Final State at Sqrt(s)

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Release : 2011
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Book Synopsis The Search for the Dark Matter Signature in the Lepton Jet Final State at Sqrt(s) by : Sergei V. Gleyzer

Download or read book The Search for the Dark Matter Signature in the Lepton Jet Final State at Sqrt(s) written by Sergei V. Gleyzer. This book was released on 2011. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: The Large Hadron Collider is pushing high energy physics in to a brand new territory. This extraordinary era may bring discoveries of unprecedented magnitude, delivering validation or extreme dissappointment to the physics theories of the previous decades. By colliding particles at more than 3.5 times the center of mass energy of the Tevatron accelerator at the Fermilab National Accelerator Laboratory, the CERN Large Hadron Collider aims to produce particles in the mass range above those that are already known. At the same time, there are exciting possibilities for new physics in the low-mass range that may have gone unnoticed until now. An example of this is a GeV-scale dark sector with a colorful spectrum of new particles. This physics model produces unique signatures of collimated leptons at the Large Hadron Collider energies. In the first part of this work, we describe the interesting astrophysical evidence that motivates a search for lepton jets and focus our attention on a minimal supersymmetric standard model with a GeV-scale dark sector that produces this exciting signature. In the next part of the thesis, we describe a search using the Compact Muon Solenoid (CMS) detector for evidence of dark matter in events containing muonic lepton-jets produced in 7 TeV proton-proton collisions at the Large Hadron Collider. We employ a novel lepton jet algorithm and find no evidence of an excess of such events with respect to the rate predicted by the Standard Model and interpret the null result in terms of a recently developed supersymmetric theory of dark matter. In doing so, we severely constrain the theoretical model and its parameters with the actual data from the Large Hadron Collider. In addition, we report the first observation of double J/Psi production, a new physical process discovery at the next energy frontier.

Search for Dark Matter with the ATLAS Detector

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Release : 2018-08-01
Genre : Science
Kind : eBook
Book Rating : 169/5 ( reviews)

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Book Synopsis Search for Dark Matter with the ATLAS Detector by : Johanna Gramling

Download or read book Search for Dark Matter with the ATLAS Detector written by Johanna Gramling. This book was released on 2018-08-01. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses searches for Dark Matter at the CERN’s LHC, the world’s most powerful accelerator. It introduces the relevant theoretical framework and includes an in-depth discussion of the Effective Field Theory approach to Dark Matter production and its validity, as well as an overview of the formalism of Simplified Dark Matter models. Despite overwhelming astrophysical evidence for Dark Matter and numerous experimental efforts to detect it, the nature of Dark Matter still remains a mystery and has become one of the hottest research topics in fundamental physics. Two searches for Dark Matter are presented, performed on data collected with the ATLAS experiment. They analyze missing-energy final states with a jet or with top quarks. The analyses are explained in detail, and the outcomes and their interpretations are discussed, also in view of the precedent analysis of theoretical approaches. Given its depth of coverage, the book represents an excellent reference guide for all physicists interested in understanding the theoretical and experimental considerations relevant to Dark Matter searches at the LHC.

Search for Dark Matter in Final States Containing Semi-visible Jets from Proton-proton Collisions at [square Root]s

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Release : 2022
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Book Synopsis Search for Dark Matter in Final States Containing Semi-visible Jets from Proton-proton Collisions at [square Root]s by : Colin Terrence Fallon

Download or read book Search for Dark Matter in Final States Containing Semi-visible Jets from Proton-proton Collisions at [square Root]s written by Colin Terrence Fallon. This book was released on 2022. Available in PDF, EPUB and Kindle. Book excerpt: "This dissertation presents a novel search for new physics using the full Run 2 dataset of 137.6 fb-1 collected by the Compact Muon Solenoid during proton-proton runs of the Large Hadron Collider. The new physics in question is dark matter production in a unique signature called semi-visible jets. Semi-visible jets are produced when a new massive mediator particle emerges from the proton-proton interaction. This mediator then decays to unstable dark matter particles which hadronize and produce a mixture of standard model particles and stable dark matter particles. The stable dark particles are only detectable as missing transverse momentum, and the standard particles are detectable as jets. This produces a signature where two jets are produced, one of which is aligned with the total missing transverse momentum. The search is presented in two phases: a classical cut-based search which uses a series of cuts based on event kinematics to select events which look like the signal signature, and a machine learning based search which uses a technique called boosted decision trees to identify semi-visible jets in a more powerful but model-dependent way. No evidence for Physics Beyond the Standard Model is observed in either search. The classical search excludes the possibility that the mediator could have a mass between 1.5 TeV and 3.98 TeV, while the model-dependent search excludes mediators with masses between 1.5 TeV and 5.08 TeV. Additionally, ranges of other signal parameters are excluded"--Page viii.

Search for Dark Matter with ATLAS

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Release : 2016-06-29
Genre : Science
Kind : eBook
Book Rating : 458/5 ( reviews)

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Book Synopsis Search for Dark Matter with ATLAS by : Ruth Pöttgen

Download or read book Search for Dark Matter with ATLAS written by Ruth Pöttgen. This book was released on 2016-06-29. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes in detail a search for weakly interacting massive particles as possible dark matter candidates, making use of so-called mono-jet events. It includes a detailed description of the run-1 system, important operational challenges, and the upgrade for run-2. The nature of dark matter, which accounts for roughly 25% of the energy-matter content of the universe, is one of the biggest open questions in fundamental science. The analysis is based on the full set of proton-proton collisions collected by the ATLAS experiment at the Large Hadron Collider at √s = 8 TeV. Special attention is given to the experimental challenges and analysis techniques, as well as the overall scientific context beyond particle physics. The results complement those of non-collider experiments and yield some of the strongest exclusion bounds on parameters of dark matter models by the end of the Large Hadron Collider run-1. Details of the upgrade of the ATLAS Central Trigger for run-2 are also included.

Search for the Production of Dark Matter in Association with Top-Quark Pairs in the Single-Lepton Final State in Proton-Proton Collisions at $\sqrt{s}$

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Release : 2015
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Book Synopsis Search for the Production of Dark Matter in Association with Top-Quark Pairs in the Single-Lepton Final State in Proton-Proton Collisions at $\sqrt{s}$ by :

Download or read book Search for the Production of Dark Matter in Association with Top-Quark Pairs in the Single-Lepton Final State in Proton-Proton Collisions at $\sqrt{s}$ written by . This book was released on 2015. Available in PDF, EPUB and Kindle. Book excerpt: A search is presented for particle dark matter produced in association with a pair of top quarks in pp collisions at a centre-of-mass energy of s√=8 TeV. The data were collected with the CMS detector at the LHC and correspond to an integrated luminosity of 19.7 fb-1. This search requires the presence of one lepton, multiple jets, and large missing transverse energy. No excess of events is found above the SM expectation, and upper limits are derived on the production cross section. Interpreting the findings in the context of a scalar contact interaction between fermionic dark matter particles and top quarks, lower limits on the interaction scale are set. These limits are also interpreted in terms of the dark matter-nucleon scattering cross sections for the spin-independent scalar operator and they complement direct searches for dark matter particles in the low mass region.

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