Download or read book Studies of Jets Subjets and Higgs Searches with the ATLAS Detector written by Sarah J. Baker and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Studies of Jets Subjets and Higgs Searches with the ATLAS Detector written by S. J. Baker and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Searches for New Physics Using Jets with the ATLAS Detector written by Aviv Ruben Cukierman and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Large Hadron Collider produces particle collisions at the highest energies ever observed in a scientific experiment. This apparatus is built to test the predictions of the Standard Model of Particle Physics, including the existence and properties of the Higgs boson. As a proton-proton collider, quarks and gluons are produced in abundance, which quickly fragment and hadronize into collimated showers of energy called jets. These jets are detected and measured in the ATLAS detector, which is built around the point of the proton-proton collisions to observe the products of these interactions. Three major original research efforts are presented using data from proton-proton collisions observed in ATLAS. The first analyzes events with jets and photons to search for a beyond-the-Standard-Model decay of the Higgs boson. The second utilizes novel techniques in weak supervision to perform a generic data-driven resonance search in events with two jets. The third formalizes the calibration of the jet energies observed in the ATLAS detector, and further proposes a new method to improve this calibration with machine learning. The work presented here addresses some of the key questions in particle physics today. By searching for new physics, it is possible to shed light on the nature of the Higgs boson and the possibility of physics beyond the Standard Model. These searches focus on processes involving multiple jets in the final state, which motivates innovations in the reconstruction of jet energies. In addition to setting new bounds on theoretically interesting models, the innovations in object reconstruction and analysis techniques developed in this work can be applied in other ATLAS efforts using currently available data or data gathered in the future.

Download or read book Search for the Higgs Boson in the Vector Boson Fusion Channel at the ATLAS Detector written by Eric Ouellette and published by Springer. This book was released on 2015-01-20 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Thesis describes the first measurement of, and constraints on, Higgs boson production in the vector boson fusion mode, where the Higgs decays to b quarks (the most common decay channel), at the LHC. The vector boson fusion mode, in which the Higgs is produced simultaneously with a pair of quark jets, provides an unparalleled opportunity to study the detailed properties of the Higgs, including the possibility of parity and CP violation, as well as its couplings and mass. It thus opens up this new field of study for precision investigation as the LHC increases in energy and intensity, leading the way to this new and exciting arena of precision Higgs research.

Download or read book ATLAS Measurements of the Higgs Boson Coupling to the Top Quark in the Higgs to Diphoton Decay Channel written by Jennet Elizabeth Dickinson and published by Springer Nature. This book was released on 2021-11-16 with total page 233 pages. Available in PDF, EPUB and Kindle. Book excerpt: During Run 2 of the Large Hadron Collider, the ATLAS experiment recorded proton-proton collision events at 13 TeV, the highest energy ever achieved in a collider. Analysis of this dataset has provided new opportunities for precision measurements of the Higgs boson, including its interaction with the top quark. The Higgs-top coupling can be directly probed through the production of a Higgs boson in association with a top-antitop quark pair (ttH). The Higgs to diphoton decay channel is among the most sensitive for ttH measurements due to the excellent diphoton mass resolution of the ATLAS detector and the clean signature of this decay. Event selection criteria were developed using novel Machine Learning techniques to target ttH events, yielding a precise measurement of the ttH cross section in the diphoton channel and a 6.3 $\sigma$ observation of the ttH process in combination with other decay channels, as well as stringent limits on CP violation in the Higgs-top coupling.

Download or read book Studies of Possible Improvements to the B Jet Energy Resolution Applied to the Search for the Higgs Boson Produced in Association with a W Boson at the ATLAS Detector written by Thomas Oliver Ravenscroft and published by . This book was released on 2015 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Road to Discovery written by John Alison and published by Springer. This book was released on 2014-09-11 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt: The research presented here includes important contributions on the commissioning of the ATLAS experiment and the discovery of the Higgs boson. The thesis describes essential work on the alignment of the inner tracker during the commissioning of the experiment and development of the electron identification algorithm. The subsequent analysis focuses on the search for the Higgs boson in the WW channel, including the development of a method to model the critical W+jet background. In addition, the thesis provides excellent introductions, suitable for non-specialists, to Higgs physics, to the LHC, and to the ATLAS experiment.

Download or read book Search for the Higgs Boson in the WH lvbb Channel with the ATLAS Detector written by Kazuya Mochizuki and published by . This book was released on 2015 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: In July 2012, the ATLAS and CMS collaborations announced the discovery of a new particle at a mass of about 125 GeV, compatible with the Higgs boson predicted by the Standard Model (SM) ofparticle physics. Although all measurements as of Summer 2015 show a full consistency with the SM predictions, the H->bb decay channel has not been seen yet as clearly as the other decay channels. This thesis presents a search for the Higgs boson in the WH->lvbb channel, using proton-proton collision data at sqrt(s) = 8 TeV taken with the ATLAS detector in the year 2012, corresponding to an integrated luminosity of 20.3 fb-1. This document details in particular one of the contributions made by the author in this search: the additional analysis region with muon events triggered by missing transverse momentum. An excess over the background-only hypothesis has been found with a significance of 1.8 sigma while 1.5 sigma was expected. The observed (expected) upper limit on the cross-section times branching ratio for WH->lvbb at 95% confidence level is found to be 2.35 (1.37) times the SM prediction at mH = 125 GeV. This search highly relies on the identification of jets originating in b-quark fragmentation, so-called b-tagging. In order to improve the H->bb search and other physics analyses using b-tagging in ATLAS, the development of high performance b-tagging algorithms has been performed and is presented also in this thesis. A new b-tagging algorithm, called MV2, is introduced: it improves the b-tagging performance significantly and is now the baseline b-tagging algorithm in ATLAS for the Run-2 analyses.

Download or read book Searches for Supersymmetry and Dark Matter in Final States with B jets and ETmiss Utilising the Higgs Boson as a Handle for New Physics with the ATLAS Detector written by Hamish Teagle and published by . This book was released on 2022 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measuring the Standard Model and Searching for New Physics with Jet Substructure Using the ATLAS Detector written by Maximilian Swiatlowski and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Collisions at the Large Hadron Collider have offered an unprecedented window into some of the highest energy scales ever observed in experiments. Understanding these collisions, especially those that produce particles charged under quantum chromodynamics (QCD), requires a deep understanding of jets: the collimated sprays of particles produced by the parton shower and hadronization processes which emerge from the asymptotic freedom of QCD. Recent theoretical advances and the unprecedented capabilities of the ATLAS detector have enabled a new class of jet physics measurements based on the internal structure of jets, referred to as jet substructure. Three new types of measurements relying on jet substructure are presented. The first is a set of measurements sensitive which can discriminate between jets initiated by quarks and gluons. Separation is possible by studying variables sensitive to the magnitude of the color charge. Several such variables are measured, and a data-driven technique is used to construct a tagger, the first of its kind at a hadron collider, which can improve the sensitivity of searches for new physics in hadronic final states. A second measurement studies the color connections of jets in top-antitop events using an observable called the jet pull angle: sensitivity to the color representation of particles decaying to dijet pairs at a hadron collider is demonstrated for the first time. A final analysis searches for R-parity violating supersymmetry (SUSY) in all hadronic final states. These classes of models remove the characteristic missing energy signature which existing SUSY searches rely on, and require new discrimination techniques. Jet substructure provides a powerful handle to analyze these very high multiplicity states using a variable called the total jet mass. No signal is observed over the Standard Model (SM) prediction, and new limits are set on these previously unexplored models. The techniques of jet substructure lie at the hearts of all of these analyses, enabling both new measurements of SM phenomena and entirely new searches for physics beyond the SM.

Download or read book Studies of Angular Correlations of Jets with the Atlas Detector written by Rajivalochan Subramaniam and published by . This book was released on 2014 with total page 642 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Search for New Physics in T t Final States with Additional Heavy flavor Jets with the ATLAS Detector written by Javier Montejo Berlingen and published by . This book was released on 2015 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Searches for Supersymmetric Particles in Final States with Multiple Top and Bottom Quarks with the Atlas Detector written by Chiara Rizzi and published by Springer Nature. This book was released on 2020-09-01 with total page 279 pages. Available in PDF, EPUB and Kindle. Book excerpt: This PhD thesis documents two of the highest-profile searches for supersymmetry performed at the ATLAS experiment using up to 80/fb of proton-proton collision data at a center-of-mass energy of 13 TeV delivered by the Large Hadron Collider (LHC) during its Run 2 (2015-2018). The signals of interest feature a high multiplicity of jets originating from the hadronisation of b-quarks and large missing transverse momentum, which constitutes one of the most promising final state signatures for discovery of new phenomena at the LHC. The first search is focused on the strong production of a pair of gluinos, with each gluino decaying into a neutralino and a top-antitop-quark pair or a bottom-antibottom-quark pair. The second search targets the pair production of higgsinos, with each higgsino decaying into a gravitino and a Higgs boson, which in turn is required to decay into a bottom-antibottom-quark pair. Both searches employ state-of-the-art experimental techniques and analysis strategies at the LHC, resulting in some of the most restrictive bounds available to date on the masses of the gluino,neutralino, and higgsino in the context of the models explored.

Download or read book A Search for Exotic Higgs Decays written by Jackson Burzynski and published by Springer Nature. This book was released on 2023-05-23 with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt: The absence of new physics at the TeV scale observed thus far at the Large Hadron Collider (LHC) motivates an increasing focus on searches for weakly-coupled new particles and exotic signatures. In particular, particles with macroscopic mean proper lifetimes, known as long-lived particles (LLPs), are of significant interest due to their ability to elude the majority of searches which rely on the assumption that Beyond Standard Model particles decay close to the primary interaction point. Many models which aim to solve various issues with the Standard Model (SM) introduce new particles with lifetimes that are either unconstrained, or even shown to prefer the macroscopic regime. These theories often point to the Higgs boson as a possible portal to new physics, with exotic Higgs decays being the primary phenomenological consequence and means of discovery. It is well motivated both from theory and experimental constraints to consider the scenario in which the particles produced in these exotic decays have macroscopic proper lifetimes and give rise to unique detector signatures. This work describes a search for exotic decays of the Higgs boson to two long-lived, neutral, spin-0 particles which subsequently decay to pairs of b quarks, giving the striking signature of displaced hadronic jets in the ATLAS inner detector. Several other ATLAS searches have probed this decay topology previously, excluding branching ratios of the Higgs boson to LLPs of more than 10% for proper lifetimes greater than 100mm. These searches relied on dedicated triggers designed to select events with LLPs decaying in the ATLAS calorimeter or muon spectrometer. The lack of an equivalent trigger for LLP decays in the ATLAS inner detector has been a limiting factor in probing LLP lifetimes less than 100mm. To circumvent the difficulty of triggering on LLP decays, the search presented in this thesis exploits the ZH associated production mode, relying on leptonic trigger signatures to select interesting events. This is the first search for Higgs boson decays into LLPs to exploit this analysis methodology and additionally makes use of several novel methods for both background rejection and background estimation. No excess over Standard Model predictions is observed, and upper limits are set on the branching ratio of the Higgs boson to LLPs . Depending on the mass of the LLP, branching ratios greater than 10% are excluded for lifetimes as small as 4mm and as large as 100mm, probing an important gap in the ATLAS exotic Higgs decay programme. In comparison to the previous searches for Higgs decays to LLPs, these are among the most stringent limits placed on this scenario, and for LLPs with masses below 40 GeV these results represent the strongest existing constraints on the branching ratio of the Higgs boson to LLPs in this lifetime regime.

Download or read book Search for the Higgs Boson Produced in Association with a Z Boson and Decaying to a Pair of Bottom Quarks with the Atlas Experiment at LHC written by Lion Alio and published by . This book was released on 2014 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: Search for the Higgs poson produced in association with a Z boson and decaying to a pair of b-quarks. This study is implemented with the ATLAS experience at LHC. This research includes the work on identification of b-jets in ATLAS detector, study of triggers of missing transverse energy and introduce a new trigger which is expected to gain more signal significance. The search for the Higgs boson is followed with the implementation of the new trigger and do the statistical analysis to estimate the significance gain in comparison with the analysis which use the nominal triggers.

Download or read book Searches with the ATLAS Detector for New Coloured Particles in the Jets Missing Energy Channel in Early LHC Data written by Christopher Young and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: