Searches for Supersymmetric Particles in Final States with Multiple Top and Bottom Quarks with the Atlas Detector

Searches for Supersymmetric Particles in Final States with Multiple Top and Bottom Quarks with the Atlas Detector
Title Searches for Supersymmetric Particles in Final States with Multiple Top and Bottom Quarks with the Atlas Detector PDF eBook
Author Chiara Rizzi
Publisher Springer Nature
Pages 284
Release 2020-09-01
Genre Science
ISBN 3030528774

Download Searches for Supersymmetric Particles in Final States with Multiple Top and Bottom Quarks with the Atlas Detector Book in PDF, Epub and Kindle

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.

Supersymmetric Beasts and Where to Find Them

Supersymmetric Beasts and Where to Find Them
Title Supersymmetric Beasts and Where to Find Them PDF eBook
Author Marco Valente
Publisher Springer Nature
Pages 231
Release 2022-03-05
Genre Science
ISBN 3030940470

Download Supersymmetric Beasts and Where to Find Them Book in PDF, Epub and Kindle

After an extensive overview of the Standard Model and of the theory and phenomenology of Supersymmetry, this book describes the recent development of the ATLAS Particle Flow algorithm, a hadronic reconstruction technique aiming at enhancing the sensitivity of the experiment to new physics through the combination of the information from different ATLAS sub-detectors. The first ever ATLAS strong SUSY search exploiting this technique is also described, reporting the results and exclusion limits obtained using the complete proton-proton collision dataset recorded by the ATLAS experiment during the second Run of the Large Hadron Collider (LHC).

Phenomena Beyond the Standard Model: What Do We Expect for New Physics to Look Like?

Phenomena Beyond the Standard Model: What Do We Expect for New Physics to Look Like?
Title Phenomena Beyond the Standard Model: What Do We Expect for New Physics to Look Like? PDF eBook
Author Roman Pasechnik
Publisher Frontiers Media SA
Pages 180
Release 2020-09-03
Genre Science
ISBN 2889639908

Download Phenomena Beyond the Standard Model: What Do We Expect for New Physics to Look Like? Book in PDF, Epub and Kindle

This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contact.

Search for New Physics in tt ̅ Final States with Additional Heavy-Flavor Jets with the ATLAS Detector

Search for New Physics in tt ̅ Final States with Additional Heavy-Flavor Jets with the ATLAS Detector
Title Search for New Physics in tt ̅ Final States with Additional Heavy-Flavor Jets with the ATLAS Detector PDF eBook
Author Javier Montejo Berlingen
Publisher Springer
Pages 288
Release 2016-07-20
Genre Science
ISBN 3319410512

Download Search for New Physics in tt ̅ Final States with Additional Heavy-Flavor Jets with the ATLAS Detector Book in PDF, Epub and Kindle

This doctoral thesis focuses on the search for new phenomena in top-antitop quark (tt) final states with additional b-quark jets at the LHC. It uses the full Run 1 dataset collected by the ATLAS experiment in proton-proton collisions at √s=8 TeV. The final state of interest consists of an isolated lepton, a neutrino and at least six jets with at least four b-tagged jets, a challenging experimental signature owing to the large background from tt+heavy-flavor production. This final state is characteristic of ttH production, with the Higgs boson decaying into bb, a process that allows direct probing of the top-Higgs Yukawa coupling. This signature is also present in many extensions of the Standard Model that have been proposed as solutions to the hierarchy problem, such as supersymmetry or composite Higgs models, which predict the pair production of bosonic or fermionic top quark partners, or the anomalous production of four-top-quark events. All these physics processes have been searched for using an ambitious search strategy that has been developed on the basis of a combination of state-of-art theoretical predictions and a sophisticated statistical analysis to constrain in-situ the large background uncertainties. As a result, the most restrictive bounds to date on the above physics processes have been obtained.

Theoretical Studies on Extended Higgs Sectors Towards Future Precision Measurements

Theoretical Studies on Extended Higgs Sectors Towards Future Precision Measurements
Title Theoretical Studies on Extended Higgs Sectors Towards Future Precision Measurements PDF eBook
Author Masashi Aiko
Publisher Springer Nature
Pages 268
Release 2023-05-20
Genre Science
ISBN 9819913241

Download Theoretical Studies on Extended Higgs Sectors Towards Future Precision Measurements Book in PDF, Epub and Kindle

This book investigates the physics of the discovered Higgs boson and additional Higgs bosons in the extended Higgs models which includes higher-order quantum corrections. While the 125 GeV Higgs boson was discovered, the structure of the Higgs sector is still a mystery. Since the Higgs sector determines the concrete realization of the Higgs mechanism, the study of its nature is one of the central interests in current and future high-energy physics. The book begins with a review of the standard model and the two-Higgs doublet model, which is one of the representatives of the extended Higgs models. Subsequently, we discuss the studies of the two-Higgs doublet model at the lowest order of perturbation. Following the lowest-order analysis, we study the higher-order electroweak corrections in Higgs physics. After reviewing the renormalization procedure and the higher-order corrections in the decays of the discovered Higgs boson, we discuss the higher-order corrections in the Higgs strahlung process from an electron-positron collision, the decays of the additional charged and CP-odd Higgs bosons in the two-Higgs doublet model. From the series of these studies, it is found that the nature of the Higgs sector can be widely investigated by future collider experiments.

Searching for Squarks

Searching for Squarks
Title Searching for Squarks PDF eBook
Author Samuel Jones
Publisher Springer Nature
Pages 235
Release 2020-08-27
Genre Science
ISBN 3030542882

Download Searching for Squarks Book in PDF, Epub and Kindle

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.

Energy and Water Development Appropriations for 2005

Energy and Water Development Appropriations for 2005
Title Energy and Water Development Appropriations for 2005 PDF eBook
Author United States. Congress. House. Committee on Appropriations. Subcommittee on Energy and Water Development
Publisher
Pages 1444
Release 2004
Genre Energy development
ISBN

Download Energy and Water Development Appropriations for 2005 Book in PDF, Epub and Kindle