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Author : Daniel Robert Abercrombie
Publisher :
ISBN 13 :
Total Pages : 83 pages
Book Rating : 4.:/5 (88 download)
Download or read book A Search for Dark Matter Via Higgs Decay Using Quark Jet Substructure written by Daniel Robert Abercrombie and published by . This book was released on 2014 with total page 83 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Yangyang Cheng
Publisher : Springer
ISBN 13 : 331944218X
Total Pages : 183 pages
Book Rating : 4.3/5 (194 download)
Download or read book Search for Dark Matter Produced in Association with a Higgs Boson Decaying to Two Bottom Quarks at ATLAS written by Yangyang Cheng and published by Springer. This book was released on 2016-09-29 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Author : Jue Chen
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (122 download)
Download or read book Search for Dark Matter Coupled to the Higgs Boson at the Large Hadron Collider written by Jue Chen and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This work presents the search for Dark Matter particles associated with the Higgs Boson decaying into a b b-bar quark pair. The dark matter search result is based on proton-proton collision data collected at a center-of-mass energy of 13 TeV by the ATLAS detector during Run II. The results are interpreted in the context of a simplified model (Z'-2HDM) which describes the interaction of dark matter and standard model particles via new heavy mediator particles. The new powerful Higgs tagging techniques, which exploit the jet substructure and heavy flavor information to a large extent, are developed to improve the search sensitivity of the search. The target physics signals are signature with an optimized search region and interpreted with background estimation result statistically.
Author : Simone Marzani
Publisher : Springer
ISBN 13 : 3030157091
Total Pages : 205 pages
Book Rating : 4.0/5 (31 download)
Download or read book Looking Inside Jets written by Simone Marzani and published by Springer. This book was released on 2019-05-11 with total page 205 pages. Available in PDF, EPUB and Kindle. Book excerpt: This concise primer reviews the latest developments in the field of jets. Jets are collinear sprays of hadrons produced in very high-energy collisions, e.g. at the LHC or at a future hadron collider. They are essential to and ubiquitous in experimental analyses, making their study crucial. At present LHC energies and beyond, massive particles around the electroweak scale are frequently produced with transverse momenta that are much larger than their mass, i.e., boosted. The decay products of such boosted massive objects tend to occupy only a relatively small and confined area of the detector and are observed as a single jet. Jets hence arise from many different sources and it is important to be able to distinguish the rare events with boosted resonances from the large backgrounds originating from Quantum Chromodynamics (QCD). This requires familiarity with the internal properties of jets, such as their different radiation patterns, a field broadly known as jet substructure. This set of notes begins by providing a phenomenological motivation, explaining why the study of jets and their substructure is of particular importance for the current and future program of the LHC, followed by a brief but insightful introduction to QCD and to hadron-collider phenomenology. The next section introduces jets as complex objects constructed from a sequential recombination algorithm. In this context some experimental aspects are also reviewed. Since jet substructure calculations are multi-scale problems that call for all-order treatments (resummations), the bases of such calculations are discussed for simple jet quantities. With these QCD and jet physics ingredients in hand, readers can then dig into jet substructure itself. Accordingly, these notes first highlight the main concepts behind substructure techniques and introduce a list of the main jet substructure tools that have been used over the past decade. Analytic calculations are then provided for several families of tools, the goal being to identify their key characteristics. In closing, the book provides an overview of LHC searches and measurements where jet substructure techniques are used, reviews the main take-home messages, and outlines future perspectives.
Author : Johanna Gramling
Publisher : Springer
ISBN 13 : 3319950169
Total Pages : 290 pages
Book Rating : 4.3/5 (199 download)
Download or read book Search for Dark Matter with the ATLAS Detector written by Johanna Gramling and published by Springer. This book was released on 2018-08-01 with total page 290 pages. 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.
Download or read book Search for Dark Matter Produced in Association with a Higgs Boson Decaying to Two Bottom Quarks in Pp Collisions at S written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This study reports on a search for dark matter pair production in association with a Higgs boson decaying to a pair of bottom quarks, using data from 20.3 fb–1 of pp collisions at a center-of-mass energy of 8 TeV collected by the ATLAS detector at the LHC. The decay of the Higgs boson is reconstructed as a high-momentum bb¯ system with either a pair of small-radius jets, or a single large-radius jet with substructure. The observed data are found to be consistent with the expected Standard Model backgrounds. Model-independent upper limits are placed on the visible cross sections for events with a Higgs boson decaying into bb¯ and large missing transverse momentum with thresholds ranging from 150 to 400 GeV. Results are interpreted using a simplified model with a Z' gauge boson decaying into different Higgs bosons predicted in a two-Higgs-doublet model, of which the heavy pseudoscalar Higgs decays into a pair of dark matter particles. Exclusion limits are also presented for the mass scales of various effective field theory operators that describe the interaction between dark matter particles and the Higgs boson.
Author : Siddharth Madhavan Narayanan
Publisher :
ISBN 13 :
Total Pages : 163 pages
Book Rating : 4.:/5 (113 download)
Download or read book Searching for Dark Matter Using Jets and Jet Substructure at the Large Hadron Collider written by Siddharth Madhavan Narayanan and published by . This book was released on 2019 with total page 163 pages. Available in PDF, EPUB and Kindle. Book excerpt: Astrophysical observations of gravitational interactions provide strong evidence for the existence of dark matter. Many theories propose and experiments test the hypothesis that dark matter may have a particle physics origin, but this remains unproven. One such experiment is the Compact Muon Solenoid at the Large Hadron Collider. If dark matter couples, at least lightly, to the Standard Model, then it is possible to produce it in collisions at the LHC. Because it would not interact with the detector, we must look for collisions in which dark matter is produced in association with one or more SM particles. This thesis describes two such analyses: dark matter plus one top quark and dark matter plus two light quarks. Both cases result in complicated detector signatures due to the hadronization of final-state quarks. Recently developed jet substructure techniques were applied using novel methods to identify the hadronization products of high-momentum top quarks. In both analyses, the observed data is found to be consistent with SM backgrounds. We translate these results into the most stringent constraints to date on the relevant beyond-SM models.
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Author : Paul Moder
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (137 download)
Download or read book Search for Dark Matter in Association with a Top Quark and a W-boson in [square Root]s written by Paul Moder and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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
Author : Matthew Baca
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (143 download)
Download or read book Search for Production of Dark Matter in Association with a Higgs Boson Decaying to Bb with the ATLAS Detector written by Matthew Baca and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Using 3.2 fb^-1 of sqrt(s) =13TeV proton-proton data collected in 2015 with the ATLAS detector at the Large Hadron Collider, new limits were imposed on the associated production of Dark Matter with a 125GeV Higgs boson which decays into a pair of b-quarks. The final state of the signal is a pair of b-quark jets and large Missing Transverse Momentum attributed to the DM escaping the detector. The dominant backgrounds were simulated. These were subject to selection requirements to increase signal to background ratio. Three regions were designated based on the number of leptons in the event. 0 lepton events made up the signal region. Events with 1 and 2 leptons were control regions. Similar selection requirements were applied to the control regions as in the signal region, in order to examine a similar phase space. A blinding region was established in the 0 lepton region over the mbb distribution to mask where a reconstructed 125GeV Higgs boson would appear. The control regions and the side bands in the signal region were then fit to the mbb data distribution. Unblinding of the signal region did not result in the discovery of the decay channel, but allowed limits to be imposed.
Author : Albert M. Sirunyan
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (124 download)
Download or read book Search for Dark Matter Produced in Association with a Higgs Boson Decaying to a Pair of Bottom Quarks in Proton-proton Collisions at $\sqrt˜s} written by Albert M. Sirunyan and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Nikola Lazar Whallon
Publisher :
ISBN 13 :
Total Pages : 179 pages
Book Rating : 4.:/5 (18 download)
Download or read book Searching for Dark Matter with Boosted Higgs Decays in Proton-proton Collisions at Sqrt(s) written by Nikola Lazar Whallon and published by . This book was released on 2018 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: If Dark Matter particles interact with Standard Model particles, it could be possible to pair produce Dark Matter particles in association with a detectable Standard Model particle at a collider such as the LHC. If this associated particle is a Higgs boson, the process is called ``mono-Higgs,'' since the resulting signature is a single Higgs boson balanced by missing energy from the undetected Dark Matter particles. Various Dark Matter models predict that this process could result in very boosted Higgs bosons that, if they decay to a pair of b-quarks, are reconstructed as jets using boosted Higgs tagging techniques. This thesis presents the results of a mono-Higgs search using 79.8 fb−1 of proton-proton collision data collected at a center-of-mass energy of 13 TeV by the ATLAS detector. The observed data are found to be consistent with the expected Standard Model backgrounds. The results are interpreted and exclusion limits are set using a Z' two-Higgs-doublet model where the pseudo-scalar Higgs particle, A, couples to Dark Matter. In order to increase the sensitivity reach of the search, new boosted Higgs tagging techniques are explored and a variable radius track jet Higgs tagging technique is employed.
Download or read book Search for Dark Matter in Proton-proton Collisions at 8 TeV with Missing Transverse Momentum and Vector Boson Tagged Jets written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A search is presented for an excess of events with large missing transverse momentum in association with at least one highly energetic jet, in a data sample of proton-proton collisions at a centre-of-mass energy of 8 TeV. The data correspond to an integrated luminosity of 19.7 inverse femtobarns collected by the CMS experiment at the LHC. The results are interpreted using a set of simplified models for the production of dark matter via a scalar, pseudoscalar, vector, or axial vector mediator. Additional sensitivity is achieved by tagging events consistent with the jets originating from a hadronically decaying vector boson. This search uses jet substructure techniques to identify hadronically decaying vector bosons in both Lorentz-boosted and resolved scenarios. This analysis yields improvements of 80% in terms of excluded signal cross sections with respect to the previous CMS analysis using the same data set. No significant excess with respect to the standard model expectation is observed and limits are placed on the parameter space of the simplified models. Mediator masses between 80 and 400 GeV in the scalar and pseudoscalar models, and up to 1.5 TeV in the vector and axial vector models, are excluded.
Download or read book Search for Associated Production of Dark Matter with a Higgs Boson Decaying to $b\bar{b}$ Or $\gamma\gamma$ at $\sqrt{s}$ written by and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for dark matter is performed using events with large missing transverse momentum and a Higgs boson decaying either to a pair of bottom quarks or to a pair of photons. The data from proton-proton collisions at a center-of-mass energy of 13 TeV, collected with the CMS detector at the LHC, correspond to an integrated luminosity of 2.3 inverse-femtobarns. Results are interpreted in the context of a Z'-two-Higgs-doublet model, where a high-mass resonance Z' decays into a pseudoscalar boson A and a CP-even scalar Higgs boson, and the A decays to a pair of dark matter particles. No significant excesses are observed over the background prediction. Combining results from the two decay channels yields exclusion limits in the signal cross section in the m[Z']-m[A] phase space. The observed data exclude, for Z' coupling strength g[Z'] = 0.8 and m[A] = 300 GeV for example, the Z' mass range of 600 to 1860 GeV. This is the first result on a search for dark matter produced in association with a Higgs boson that includes constraints on h to gamma-gamma obtained at sqrt(s) = 13 TeV.
Author : Steven Schramm
Publisher : Springer
ISBN 13 : 3319444530
Total Pages : 341 pages
Book Rating : 4.3/5 (194 download)
Download or read book Searching for Dark Matter with the ATLAS Detector written by Steven Schramm and published by Springer. This book was released on 2016-11-23 with total page 341 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes the search for Dark Matter at the LHC in the mono-jet plus missing transverse momentum final state, using the full dataset recorded in 2012 by the ATLAS Experiment. It is the first time that the number of jets is not explicitly restricted to one or two, thus increasing the sensitivity to new signals. Instead, a balance between the most energetic jet and the missing transverse momentum is required, thus selecting mono-jet-like final states. Collider searches for Dark Matter have typically used signal models employing effective field theories (EFTs), even when comparing to results from direct and indirect detection experiments, where the difference in energy scale renders many such comparisons invalid. The thesis features the first robust and comprehensive treatment of the validity of EFTs in collider searches, and provides a means by which the different classifications of Dark Matter experiments can be compared on a sound and fair basis.
Author : Ruth Pöttgen
Publisher : Springer
ISBN 13 : 3319410458
Total Pages : 325 pages
Book Rating : 4.3/5 (194 download)
Download or read book Search for Dark Matter with ATLAS written by Ruth Pöttgen and published by Springer. This book was released on 2016-06-29 with total page 325 pages. 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.
Author : Andrea Matić
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (124 download)
Download or read book Search for Dark Matter in Association with a Higgs Boson Decaying Into B-quarks with the ATLAS Detector written by Andrea Matić and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Enrico Morgante
Publisher : Springer
ISBN 13 : 3319676067
Total Pages : 223 pages
Book Rating : 4.3/5 (196 download)
Download or read book Aspects of WIMP Dark Matter Searches at Colliders and Other Probes written by Enrico Morgante and published by Springer. This book was released on 2017-10-05 with total page 223 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis covers several theoretical aspects of WIMP (weakly interacting massive particles) dark matter searches, with a particular emphasis on colliders. It mainly focuses on the use of effective field theories as a tool for Large Hadron Collider (LHC) searches, discussing in detail the issue of their validity, and on simplified dark matter models, which are receiving a growing attention from the physics community. It highlights the theoretical consistency of simplified models, which is essential in order to correctly exploit their potential and for them to be a common reference when comparing results from different experiments. This thesis is of interest to researchers (both theorists and experimentalists) in the field of dark matter searches, and offers a comprehensive introduction to dark matter and to WIMP searches for students and non-experts.
