Detector Corrected Search For Dark Matter In Monojet And Vector Boson Fusion Topologies With The Atlas Detector
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Detector Corrected Search For Dark Matter In Monojet And Vector Boson Fusion Topologies With The Atlas Detector
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Author : Thomas Spieker
language : en
Publisher:
Release Date : 2019*
Detector Corrected Search For Dark Matter In Monojet And Vector Boson Fusion Topologies With The Atlas Detector written by Thomas Spieker 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.
Search For Dark Matter Produced In Association With A Higgs Boson Decaying To Two Bottom Quarks At Atlas
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Author : Yangyang Cheng
language : en
Publisher: Springer
Release Date : 2016-09-29
Search For Dark Matter Produced In Association With A Higgs Boson Decaying To Two Bottom Quarks At Atlas written by Yangyang Cheng and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-09-29 with Science categories.
This thesis reports on the search for dark matter in data taken with the ATLAS detector at CERN’s Large Hadron Collider (LHC). The identification of dark matter and the determination of its properties are among the highest priorities in elementary particle physics and cosmology. The most likely candidate, a weakly interacting massive particle, could be produced in the high energy proton-proton collisions at the LHC. The analysis presented here is unique in looking for dark matter produced together with a Higgs boson that decays into its dominant decay mode, a pair of b quarks. If dark matter were seen in this mode, we would learn directly about the production mechanism because of the presence of the Higgs boson. This thesis develops the search technique and presents the most stringent production limit to date.
Search For Invisible Higgs Boson Decays In Events With Vector Boson Fusion Signatures Using 139 Fb 1 Of Proton Proton Data Recorded By The Atlas Experiment
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Author : [Study Group] ATLAS Collaboration CERN
language : en
Publisher:
Release Date : 2022
Search For Invisible Higgs Boson Decays In Events With Vector Boson Fusion Signatures Using 139 Fb 1 Of Proton Proton Data Recorded By The Atlas Experiment written by [Study Group] ATLAS Collaboration CERN 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.
Abstract: A direct search for Higgs bosons produced via vector-boson fusion and subsequently decaying into invisible particles is reported. The analysis uses 139 fb−1 of pp collision data at a centre-of-mass energy of s√ = 13 TeV recorded by the ATLAS detector at the LHC. The observed numbers of events are found to be in agreement with the background expectation from Standard Model processes. For a scalar Higgs boson with a mass of 125 GeV and a Standard Model production cross section, an observed upper limit of 0.145 is placed on the branching fraction of its decay into invisible particles at 95% confidence level, with an expected limit of 0.103. These results are interpreted in the context of models where the Higgs boson acts as a portal to dark matter, and limits are set on the scattering cross section of weakly interacting massive particles and nucleons. Invisible decays of additional scalar bosons with masses from 50 GeV to 2 TeV are also studied, and the derived upper limits on the cross section times branching fraction decrease with increasing mass from 1.0 pb for a scalar boson mass of 50 GeV to 0.1 pb at a mass of 2 TeV
Search For Exotic Mono Jet Events
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Author : Valerio Rossetti
language : en
Publisher: Springer
Release Date : 2015-08-24
Search For Exotic Mono Jet Events written by Valerio Rossetti and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-08-24 with Science categories.
This thesis describes in detail the search for new phenomena in mono-jet final states with the ATLAS experiment at the LHC. The final state is considered the golden channel in the searches for large extra dimensions (LED) but also allows access to a very rich SUSY-related phenomenology pertaining to the production of weakly interacting massive particles (WIMPS), SUSY Dark Matter candidates, GMSB SUSY models with very light gravitino masses, as well as stop an sbottom pair production in compressed scenarios (with nearly degenerated squarks and the lightest neutralino), and also invisible Higgs searches, among others. Here, a number of these scenarios are explored. The measurements presented yield new powerful constraints on the existence of extra spatial dimensions, the pair production of WIMPs, and also provide the best limit to date on the gravitino mass.
Searching For Squarks
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Author : Samuel Jones
language : en
Publisher: Springer Nature
Release Date : 2020-08-27
Searching For Squarks written by Samuel Jones and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-08-27 with Science categories.
This thesis focuses on searches for squarks with the ATLAS detector in "compressed" scenarios where the scalar top is very close in mass to the lightest supersymmetric particle. These models are theoretically appealing because the presence of a quasi-degenerate scalar top enhances the self-annihilation cross-section of the lightest supersymmetric particle, acting therefore as a regulator of the dark matter relic density. Two main analyses are presented: the first is a search for scalar tops decaying to charm quarks. The identification of jets originating from the charm quark is very challenging due to its short lifetime. The calibration of tools for charm-tagging has paved the way to measuring the decay of the Higgs boson to pairs of charm quarks. The second analysis presented is the development of a novel technique for reconstructing low momentum b-hadrons. This tool has enabled the ATLAS collaboration to explore topologies that were previously inaccessible.
Combination And Summary Of Atlas Dark Matter Searches Interpreted In A 2hdm With A Pseudo Scalar Mediator Using 139 Fb 1 Of Square Root S
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Author : [Study Group] ATLAS Collaboration CERN
language : en
Publisher:
Release Date : 2023
Combination And Summary Of Atlas Dark Matter Searches Interpreted In A 2hdm With A Pseudo Scalar Mediator Using 139 Fb 1 Of Square Root S written by [Study Group] ATLAS Collaboration CERN 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.
Abstract: Results from a wide range of searches targeting different experimental signatures with and without missing transverse momentum (EmissT) are used to constrain a Two-Higgs-Doublet Model (2HDM) with an additional pseudo-scalar mediating the interaction between ordinary and dark matter (2HDM+a). The analyses use up to 139 fb−1 of proton-proton collision data at a centre-of-mass energy s√=13 TeV recorded with the ATLAS detector at the Large Hadron Collider between 2015-2018. The results from three of the most sensitive searches are combined statistically. These searches target signatures with large EmissT and a leptonically decaying Z boson; large EmissT and a Higgs boson decaying to bottom quarks; and production of charged Higgs bosons in final states with top and bottom quarks, respectively. Constraints are derived for several common as well as new benchmark scenarios within the 2HDM+a
Search For New Phenomena In Dijet Angular Distributions At S 8 And 13 Tev
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Author : Lene Kristian Bryngemark
language : en
Publisher: Springer
Release Date : 2017-12-29
Search For New Phenomena In Dijet Angular Distributions At S 8 And 13 Tev written by Lene Kristian Bryngemark and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-12-29 with Science categories.
This thesis describes the use of the angular distributions of the most energetic dijets in data recorded by the ATLAS experiment, at CERN’s Large Hadron Collider (LHC), the goal of which is to search for phenomena beyond what the current theory of Particle Physics (the Standard Model) can describe. It also describes the deployment of the method used in ATLAS to correct for the distortions in jet energy measurements caused by additional proton–proton interactions. The thesis provides a detailed introduction to understanding jets and dijet searches at the LHC. The experiments were carried out at two record collider centre-of-mass energies (8 and 13 TeV), probing smaller distances than ever before. Across a broad momentum transfer range, the proton constituents (quarks and gluons) display the same kinematical behaviour, and thus still appear to be point-like. Data are compared to predictions corrected for next-to-leading order quantum chromodynamics (NLO QCD) as well as electroweak effects, demonstrating excellent agreement. The results are subsequently used to set limits on parameters of suggested theoretical extensions to the Standard Model (SM), including the effective coupling and mass of a Dark Matter mediator.
Search For Dark Matter In Association With A Top Quark And A W Boson In Square Root S
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Author : Paul Moder
language : en
Publisher:
Release Date : 2022
Search For Dark Matter In Association With A Top Quark And A W Boson In Square Root S written by Paul Moder 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.
Abstract: The Standard Model (SM) is the only model in particle physics containing all observed elementary particles and their interactions. Over the years, its predictions were tested and observed in a number of experiments. However, there are still observations that can not be explained by the SM with one of the most prominent ones being the existence of Dark Matter (DM). While the existence of DM was first theorised through astronomical observations, extensions of the SM allow for a search of DM at the Large Hadron Collider (LHC) as well. Since DM can not be detected directly, final states analysing its existence at the LHC are always designed around high missing transverse energy. This thesis presents a search for DM with data collected by the ATLAS detector in the years 2015-2018 corresponding to an integrated luminosity of 139~\mathrm{fb}^{-1}$ at a center of mass energy of 13~\TeV. The analysis is based on an extended two Higgs doublet model (2HDM+a) where a pseudo-scalar mediator allows the production of DM in the final state. In addition to the DM, a top quark and a \Wboson-boson are produced in the final state. This thesis mainly focuses on a final state with zero leptons which results in both the \Wboson-boson and the top quark being required to decay hadronically. In addition to that, the \Wboson-boson can be expected to have a high momentum in the signal process. Therefore, a dedicated identification algorithm using large-radius jets is employed to select events with at least one hadronically decaying \Wboson-boson. This allows for a strong distinction against SM background events. In this analysis, several different signal processes are considered, since different parameters can affect the cross section and the distributions of the signal processes. These parameters include different values for the mass of the mediator $a$, the mass of the heavy Higgs boson $H$ and $\tan\beta$. Since no significant excess was found in the signal regions when comparing SM prediction to data, upper exclusion limits on the cross section of the signal processes were calculated with a 95\% confidence level (CL). These limits are presented in three different model parameter planes. One such plane presents the upper limits for different values of the mass of the mediator, $m_a$, and the mass of the heavy Higgs boson, $m_H$, while keeping $\tan\beta = 1$. The second and third plane present the upper limits for different values of the mass of the heavy Higgs boson, $m_H$, and $\tan\beta$ while the mass of the mediator $a$ stays constant at $m_a = 250~\GeV$ and $m_a = 150~\GeV$. In addition to the upper limits for signal processes with one top quark in the final state, this thesis also provides an upper exclusion limit where this signal process is combined with a process that includes two top quarks in the final state
The Identification Of Dark Matter
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Author : Neil J C Spooner
language : en
Publisher: World Scientific
Release Date : 2001-05-22
The Identification Of Dark Matter written by Neil J C Spooner and has been published by World Scientific this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001-05-22 with Science categories.
The objective of the workshop series “The Identification of Dark Matter” is to assess critically the status of work attempting to identify what constitutes dark matter; in particular, to consider what techniques are currently being used, how successful they are, and what new techniques are likely to improve the prospects for identifying dark matter candidates in the future. This proceedings volume includes reviews on major particle astrophysics topics in the field of dark matter, as well as short contributed papers. Contents:Dark Matter in the Universe — Theory and Observation:The Early Universe, Nucleosynthesis and CosmologyCosmic Microwave Background RadiationLarge Scale StructureHalos, Halo Models, and Dark MatterParticle Physics and SupersymmetryBaryonic Searches:Introduction to Baryonic Dark Matter SearchesDirect Observational Evidence for Baryonic Dark MatterMicrolensing Evidence for Dark MatterNext Generation Astronomical SearchesNon-Baryonic Searches:Introduction to Non-Baryonic Dark Matter SearchesWIMP DetectorsWIMP Detectors with Directional Sensitivity and Future ProspectsAxion DetectorsWIMP Detection by Indirect TechniquesNeutrino Dark Matter SearchesNext Generation Neutrino, WIMP and Axion TechniquesImplications for Astrophysical Neutrino Detection Readership: Researchers and academics/lecturers in astrophysics and high energy physics. Keywords:Dark Matter;Particle Astrophysics;Nucleosynthesis;Cosmology;Halos;Particle Physics;Supersymmetry;Detectors;Neutrino
Search For Dark Matter Produced In Association With A Standard Model Higgs Boson Decaying Into B Quarks Using The Full Run 2 Dataset From The Atlas Detector
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Author : ATLAS Collaboration CERN
language : en
Publisher:
Release Date : 2021
Search For Dark Matter Produced In Association With A Standard Model Higgs Boson Decaying Into B Quarks Using The Full Run 2 Dataset From The Atlas Detector written by ATLAS Collaboration CERN and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021 with categories.