Search For Dark Matter Produced In Association With Monotop In The Fully Leptonic Channel In Proton Proton Collisions At 13 Tev With The Compact Muon Soleniod Experiment
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Search For Dark Matter Produced In Association With Monotop In The Fully Leptonic Channel In Proton Proton Collisions At 13 Tev With The Compact Muon Soleniod Experiment
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Author : Rishabh Uniyal
language : en
Publisher:
Release Date : 2023
Search For Dark Matter Produced In Association With Monotop In The Fully Leptonic Channel In Proton Proton Collisions At 13 Tev With The Compact Muon Soleniod Experiment written by Rishabh Uniyal and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023 with categories.
A search for dark matter has been performed using the monotop model, with the dark matter signature in the form of large missing energy, presence of a b-tagged jet and an isolated lepton (electron and muon). The data analyzed in this analysis was collected from 2016-2018 amounting to an integrated luminosity of 137 $fb^{-1}$ from the proton-proton collisions at a center-of-mass energy ($\sqrt{s}$) of 13 TeV and upper exclusion limits on the mass of the dark matter mediator and the dark matter particle have been set at 95\% confidence level.
Search For Dark Matter Produced In Association With Top Quarks At The Compact Muon Solenoid
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Author : Victor Shang
language : en
Publisher:
Release Date : 2024
Search For Dark Matter Produced In Association With Top Quarks At The Compact Muon Solenoid written by Victor Shang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2024 with categories.
One of the fundamental open questions that cannot be currently explained by the Standard Model is the particle nature of dark matter. Though astrophysical observations provide indirect evidence of its existence, dark matter has not been directly measured so far. However, under certain assumptions, dark matter may be possible to produce and detect at high energy particle colliders like the LHC. This thesis presents a search for dark matter produced in association with top quarks in data collected by the CMS detector at the LHC, corresponding to 138 fb$^{-1}$ of proton-proton collisions at a center-of-mass energy of 13 TeV. Production of dark matter particles in association with both a single top quark and a pair of top quarks are considered. The search is performed in three separate channels depending on the number of leptons in the final state, which include the all hadronic, single lepton, and dileptonic final states. The primary strategy of the search is to look for an excess of events with respect to the background-only prediction in events with a large imbalance in the transverse momentum. The results are interpreted in the context of a simplified model in which either a scalar or pseudoscalar mediator couples to top quarks and to dark matter fermions. Future prospects for improving the search are also discussed.
Searching For Dark Matter With The Cms Detector In Proton Proton Collisions Containing A Single High Pt Photon And Large E Miss T
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Author : Brandon Leigh Allen
language : en
Publisher:
Release Date : 2019
Searching For Dark Matter With The Cms Detector In Proton Proton Collisions Containing A Single High Pt Photon And Large E Miss T written by Brandon Leigh Allen and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.
In this thesis, we present a search for dark matter in final states containing a high- PT photon and large missing transverse momentum in proton-proton collisions at [square root of s] = 13 TeV using data collected by the Compact Muon Solenoid.(CMS) experiment at the CERN Large Hadron Collider (LHC) corresponding to an integrated luminosity of 35.9 inverse femtobarns. The main advances in experimental technique compared to previous searches in this final state are the use of data-driven control regions to constrain the main irreducible backgrounds from Z( --> vv̄ + [gamma] and W( --> [iota]v)+ [gamma] production and an in-depth study of the unique anomolous detector signatures that result in backgrounds due to non-collision processes. With these improvements, we have the most robust analysis of this kind presented to date. No deviations from the predictions of the standard model are observed. The results are interpreted in the context of dark matter production and limits on new physics parameters are calculated at 95% confidence level. We focus on two simplified dark matter production models where new vector and axial mediators couple a new dark dirac fermion to the Standard Model quarks. These models are chosen as they cover a large class of WIMP-like dark matter particles that show up in many types of more complete new physics models. For the two models considered, the observed (expected) lower limits on the masses of the new mediators are 950 (1150) GeV for a dark matter particle of a mass of 1 GeV.
Search For Dark Matter In Final States Containing Semi Visible Jets From Proton Proton Collisions At Square Root S
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Author : Colin Terrence Fallon
language : en
Publisher:
Release Date : 2022
Search For Dark Matter In Final States Containing Semi Visible Jets From Proton Proton Collisions At Square Root S written by Colin Terrence Fallon and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022 with categories.
"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 Produced In Association With A Leptonically Decaying Z Boson In Proton Proton Collisions At S
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Author : Albert M. Sirunyan
language : en
Publisher:
Release Date : 2020
Search For Dark Matter Produced In Association With A Leptonically Decaying Z Boson In Proton Proton Collisions At S written by Albert M. Sirunyan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
Search For Dark Matter Decaying To Two Displaced Muons Produced In Proton Proton Collisions At 13 Tev With The Cms Detector And For Dark Photons Produced In Electron Positron Fixed Target Collisions At 500 Mev With The Padme Detector
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Author : Andre Sterenberg Frankenthal
language : en
Publisher:
Release Date : 2020
Search For Dark Matter Decaying To Two Displaced Muons Produced In Proton Proton Collisions At 13 Tev With The Cms Detector And For Dark Photons Produced In Electron Positron Fixed Target Collisions At 500 Mev With The Padme Detector written by Andre Sterenberg Frankenthal and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
Two novel searches for dark matter using particle accelerators are presented. The first is a search for inelastically-coupled dark matter with the CMS detector at CERN, relying on 137 inverse femtobarns of proton-proton collision data collected at 13 TeV center-of-mass energy between 2016 and 2018. The search strategy exploits the striking signature expected of inelastic dark matter: a pair of displaced, soft, and narrow muons collimated with missing transverse momentum and recoiled off an initial-state radiation jet. This is the first search for inelastic dark matter at a hadron collider. The second experiment is PADME, a small-scale detector to search for dark photons located in Frascati, Italy. PADME seeks to detect the production of dark photons in positron-electron collisions with a stationary diamond target and a 500 MeV positron beam. The missing-mass technique employed in the experiment relies on constraining all four-momenta in the system except for the dark photon and looking for a bump in the resulting invariant mass distribution corresponding to the dark photon's mass. The projected sensitivity for both experiments is compared in the context of highlighting the need for a comprehensive experimental search program for dark matter. Both analyses expect first public results by the end of 2020.
Search For Dark Matter Particles Produced In Association With A Higgs Boson In Proton Proton Collisions At S
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Author : Albert M. Sirunyan
language : en
Publisher:
Release Date : 2019
Search For Dark Matter Particles Produced In Association With A Higgs Boson In Proton Proton Collisions At S written by Albert M. Sirunyan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.
The Search For The Dark Matter Signature In The Lepton Jet Final State At Sqrt S
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Author : Sergei V. Gleyzer
language : en
Publisher:
Release Date : 2011
The Search For The Dark Matter Signature In The Lepton Jet Final State At Sqrt S written by Sergei V. Gleyzer and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
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 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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Author :
language : en
Publisher:
Release Date : 2015
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 and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
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.
Precision Measurement Of And Search For Dark Matter In The Transverse Momentum Spectra Of Z Bosons
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Author : Dylan George Hsu
language : en
Publisher:
Release Date : 2019
Precision Measurement Of And Search For Dark Matter In The Transverse Momentum Spectra Of Z Bosons written by Dylan George Hsu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.
A measurement of the differential Z boson production cross section in proton-proton collisions is presented. It furnishes a precision test of the Standard Model, and constrains the parton distribution functions of the proton. Moreover, it is a building block for future measurements of the mass of the W± boson. A study of the efficiency of lepton identification algorithms is performed which drives the precision of the measurement at lower values of transverse momentum. In tandem, a search for new physics in events with a Z boson produced in association with large missing transverse momentum is presented. The results of this search are interpreted in the context of several dark matter models: generic spin-0 or spin-1 mediators, invisible decays of a Higgs-like boson, unparticles, and large extra spatial dimensions. A multivariate analysis was developed to enhance the sensitivity of the invisible Higgs interpretation. The theoretical uncertainty on the irreducible background from electroweak diboson processes is constrained by emulating the missing energy using pure control samples in the fully leptonic final states. The data were collected with the Compact Muon Solenoid detector at the Large Hadron Collider and correspond to an integrated luminosity of 35.9 fb-1. No significant deviations from the Standard Model are found.