Download or read book Search for New Phenomena in Top Antitop Quarks Final States with Additional Heavy Flavour Jets with the ATLAS Detector written by Daiki Yamaguchi and published by Springer Nature. This book was released on 2019-10-30 with total page 279 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reports on the search for a new heavy particle, the Vector-Like Top quark (VLT), in the Large Hadron Collider (LHC) at CERN. The signal process is the pair production of VLT decaying into a Higgs boson and top quark (TT→Ht+X, X=Ht, Wb, Zt). The signal events result in top–antitop quarks final states with additional heavy flavour jets. The book summarises the analysis of the data collected with the ATLAS detector in 2015 and 2016. In order to better differentiate between signals and backgrounds, exclusive taggers of top quark and Higgs boson were developed and optimised for VLT signals. These efforts improved the sensitivity by roughly 30%, compared to the previous analysis. The analysis outcomes yield the strongest constraints on parameter space in various BSM theoretical models. In addition, the book addresses detector operation and the evaluation of tracking performance. These efforts are essential to properly collecting dense events and improving the accuracy of the reconstructed objects that are used for particle identification. As such, they represent a valuable contribution to data analysis in extremely dense environments.
Download or read book Search for New Physics in tt Final States with Additional Heavy Flavor Jets with the ATLAS Detector written by Javier Montejo Berlingen and published by Springer. This book was released on 2016-07-20 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Search for New Phenomena with Top Quark Pairs in Final States with One Lepton Jets and Missing Transverse Momentum in Pp Collisions at square Root s written by ATLAS Collaboration CERN and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: A search for new phenomena with top quark pairs in final states with one isolated electron or muon, multiple jets, and large missing transverse momentum is performed. Signal regions are designed to search for two-, three-, and four-body decays of the directly pair-produced supersymmetric partner of the top quark (stop). Additional signal regions are designed specifically to search for spin-0 mediators that are produced in association with a pair of top quarks and decay into a pair of dark-matter particles. The search is performed using the Large Hadron Collider proton-proton collision dataset at a centre-of-mass energy of s√ = 13 TeV recorded by the ATLAS detector from 2015 to 2018, corresponding to an integrated luminosity of 139 fb−1. No significant excess above the Standard Model background is observed, and limits at 95% confidence level are set in the stop-neutralino mass plane and as a function of the mediator mass or the dark-matter particle mass. Stops are excluded up to 1200 GeV (710 GeV) in the two-body (three-body) decay scenario. In the four-body scenario stops up to 640 GeV are excluded for a stop-neutralino mass difference of 60 GeV. Scalar and pseudoscalar dark-matter mediators are excluded up to 200 GeV when the coupling strengths of the mediator to Standard Model and dark-matter particles are both equal to one and when the mass of the dark-matter particle is 1 GeV
Download or read book Search for Flavor Changing Neutral Current Top Quark Decays t Hq with H bb in pp Collisions at s 8 TeV with the ATLAS Detector written by Shota Tsiskaridze and published by Springer. This book was released on 2017-08-02 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: This PhD thesis focuses on the search for flavor-changing neutral currents in the decay of a top quark to an up-type quark (q = u, c) and the Standard Model Higgs boson, where the Higgs boson decays to bb. Further, the thesis presents the combination of this search for top quark pair events with other ATLAS searches – in the course of which the most restrictive bounds to date on tqH interactions were obtained. Following on from the discovery of the Higgs boson, it is particularly important to measure the Yukawa couplings of the Standard Model fermions; these parameters may provide crucial insights to help solve the flavor puzzle and may help reveal the presence of new physics before it is directly observed in experiments.
Download or read book Search for Heavy Down Type Vector Like Quarks in the Lepton Plus Jets Final State in 8 TeV Proton proton Collisions Using the ATLAS Detector at the LHC written by Diedi Hu and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In the chiral B scenario with a 100% branching ratio of the decay B->Wt, the observed (expected) 95% CL lower limit on the B mass is 814 GeV (756 GeV).
Download or read book Search for New Phenomena in a Mono jet Plus Missing Transverse Energy Final State with the ATLAS Detector at the LHC written by Sahill Poddar and published by . This book was released on 2013 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Search for Massive Resonances in Final States with Boosted Top antitop Pairs Decaying Into a Lepton and Jets with the ATLAS Detector at the Large Hadron Collider written by Janna Katharina Behr and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for New Phenomena in Final States with Large Jet Multiplicities and Missing Transverse Momentum with ATLAS Using written by and published by . This book was released on 2016 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results are reported of a search for new phenomena, such as supersymmetric particle production, that could be observed in high-energy proton–proton collisions. Events with large numbers of jets, together with missing transverse momentum from unobserved particles, are selected. The data analysed were recorded by the ATLAS experiment during 2015 using the 13 TeV centre-of-mass proton–proton collisions at the Large Hadron Collider, and correspond to an integrated luminosity of 3.2 fb-1. The search selected events with various jet multiplicities from ≥7 to ≥10 jets, and with various b-jet multiplicity requirements to enhance sensitivity. Furthermore, no excess above Standard Model expectations is observed. The results are interpreted within two supersymmetry models, where gluino masses up to 1400 GeV are excluded at 95% confidence level, significantly extending previous limits.
Download or read book Measurement of Jets Produced in Top Quark Events Using the Emu Final State with 2 B tagged Jets in Pp Collisions at 8 TeV with the ATLAS Detector written by Jacquelyn Kay Brosamer and published by . This book was released on 2016 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: The transverse momentum and multiplicity of jets produced in top quark events are measured using 20.3 inverse fb of pp collision data at a center-of-mass energy of 8 tev. Jets are selected from top events requiring an opposite-charge $e\mu$ pair and two b-tagged jets in the final state. The data are corrected to obtain the particle-level fiducial cross section for additional jets with rank 1-4, where rank=1 is the leading additional jet. These distributions are used to obtain the extra jet multiplicity as a function of minimum jet pt threshold. The results are compared with several next to leading order Monte Carlo generators. The resulting measurements can be used to tune Monte Carlo QCD modelling and may also reduce associated modelling uncertainties for LHC top quark physics measurements.
Download or read book Search for Scalar Bottom Quarks in Compressed Final States with B jets and Missing Transverse Momentum with the ATLAS Detector written by Mario Spina 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 Searches for Supersymmetric Particles in Final States with Multiple Top and Bottom Quarks with the ATLAS Detector written by Chiara Rizzi and published by . This book was released on 2018 with total page 257 pages. Available in PDF, EPUB and Kindle. Book excerpt: En esta tesis se presentan dos búsquedas de Supersimetría en colisiones protón-protón en el Gran Colisionador de Hadrones (LHC, por sus siglas en inglés) del CERN, centradas en modelos que dan lugar a la producción de múltiples quarks top o quarks bottom en el estado final. La primera búsqueda tiene como objetivo la producción de pares de gluinos, donde cada gluino de desintegra a través de un squark top (modelo Gtt) o un squark bottom (modelo Gbb) en una pareja de quarks top-antitop o bottom-antibottom, respectivamente, y un neutralino, que es la partícula supersimétrica más ligera (LSP, por sus siglas en inglés). Cada quak top a su vez se desintegra en un bosón W y un quark bottom. Consecuentemente, el estado final se caracteriza por una alta multiplicidad de bottom jets (b-jets), que son chorros de partículas resultantes de la hadronización de quarks bottom, así como un alto momento transverso faltante (Emiss T ) debido a que la LSP escapa sin ser detectada. La segunda búsqueda tiene como objetivo la producción de pares de higgsinos en el contexto de un modelo GGM, en el cual cada higgsino se desintegra en el bosón de Higgs del Model Estándar y un gravitino, que en este caso juega el papel de la LSP. Esta búsqueda se centra en sucesos donde ambos bosones de Higgs se desintegran en parejas de quarks bottom-antibottom, de nuevo dado lugar a estados finales con múltiples b-jets. Este es el primer análisis en ATLAS optimizado para esta signatura, la cual había sido considerada previamente en búsquedas llevadas a cabo por la colaboración CMS. Ambas búsquedas en esta tesis usan los datos recopilados por el experimento ATLAS en el LHC entre el 2015 y el 2016, a una energía del centro de masas de ps = 13 TeV, correspondiente a una luminosidad integrada de 36.1 fb−1. La búsqueda de gluinos, sin optimización adicional, ha sido extendida usando los datos recopilados en el 2017, resultando en una luminosidad integrada total de 79.8 fb−1. No habiendo encontrado un exceso significativo de sucesos sobre la predicción del Modelo Estándar en ninguna de las regiones de búsqueda, los resultados han sido usados para establecer límites superiores a la producción de partículas supersimétricas. La primera búsqueda excluye a un nivel de confianza del 95% masas del gluino de hasta 2.25 TeV para el modelo Gtt y de hasta 2.17 TeV para el modelo Gbb, en ambos casos para masas del neutralino menores que 800 GeV. La segunda búsqueda excluye masas del higgsino en el rango de 240–880 GeV, asumiendo que el higgsino se descompone exclusivamente en un bosón de Higgs y un gravitino.
Download or read book A Search for Top antitop Quark Resonances with the ATLAS Detector at the LHC written by Anna Duncan and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Seeing a Single Top Quark written by Harish Potti and published by . This book was released on 2020 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: The top quark is the heaviest known elementary particle. With a coupling to the Higgs boson close to unity, the top quark plays a special role in electroweak symmetry breaking as well as in physics beyond the Standard Model. An accurate measurement of its properties can provide key information for understanding the physics at the TeV scale. In this dissertation, two measurements of the top quark properties are presented. The first part of this dissertation presents the first-ever ATLAS search for the associated production of a single top quark and a photon. This analysis is performed with 139 fb−1 of pp collision data collected by the ATLAS detector at the LHC at [square root symbol] s = 13 TeV. Only final states with exactly one lepton and at least one photon are considered in this analysis. In the second part, results from the combination of ATLAS searches for flavor changing neutral currents (FCNC) in t->Hq decays are presented. Four FCNC analyses, probing different Higgs decay modes, performed with 36.1 fb−1 of proton-proton collision data collected by the ATLAS detector in 2015-2016 are considered in the combination. They search for top-quark pair events in which one top quark decays into Wb and the other top quark decay into Hq
Download or read book Search for Top antitop Quark Resonances in the Lepton jets Final State with the CMS Detector Preparing the Run 3 Analysis written by Johanna Matthiesen and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for New Physics with Top Quark Pairs in the Fully Hadronic Final State at the ATLAS Experiment written by Mathis Kolb and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for New Physics with Top and Bottom Quarks with ATLAS written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The studies performed by the principal investigator during the period of the grant constitute the ground work for search for new physics in channels including top and bottom quarks with the ATLAS detector at the Large Hadron Collider. The PI has been involved in search for heavy charged Higgs bosons decaying into top and bottom quark pairs, and top quark rare decays involving Higgs bosons and c-quarks. Both channels have the top quark pair production as their main background, which was studied in detail. The search for heavy charged Higgs and top quark rare decays requires signi cant amount of data accumulated by the experiment. In case no signal is observed in the present data sample collected by ATLAS (5 fb−1 of integrated luminosity at proton-anti proton center-of-mass energy of 7 TeV and 20 fb−1 at 8 TeV), data from the upgraded detector running at 14 TeV needs to be analyzed. The PI has been working on physics and performance studies at upgraded detector.
Download or read book Searches for New Resonances Decaying to Top antitop Quark Pairs with the ATLAS Detector in Sqrt s written by Stephen Swedish and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
