Download or read book Search for a Higgs Boson in the H ZZ and ZH ll invisible Channels with the ATLAS Detector written by Joseph Price 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 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 A Beauty ful Boson written by Giulia Di Gregorio and published by Springer Nature. This book was released on 2023-01-01 with total page 229 pages. Available in PDF, EPUB and Kindle. Book excerpt: The analysis described in this thesis is the search for the Higgs boson, decaying into bb pair, in the associated production with a vector boson, in the extreme Higgs boson transverse momentum region where the Higgs boson is reconstructed using the large-R jet technique. The use of the large-R jets allows to add a part of the phase space unexplored so far, which is particularly sensitive to possible new physics. The analysed data have been collected at LHC by the ATLAS detector between 2015 and 2018 at a centre-of-mass energy of √s = 13 TeV. The same dataset has been used to perform the differential pp → ZH and pp → WH cross-section measurements used to extract the information on the Higgs couplings and to put limits on Beyond the Standard Model effects. Furthermore the analysis has been re-used to perform a cross-section measurement of the diboson ZZ and WZ processes because the diboson and the Higgs processes have a similar topology. For the first time the ZZ(bb) and WZ(bb) cross-sections are measured at √s = 13 TeV and the observed cross-section measurements are consistent with the Standard Model predictions.

Download or read book Discovery and Measurement of the Higgs Boson in the WW Decay Channel written by David Hall and published by Springer. This book was released on 2015-06-15 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes the stand-alone discovery and measurement of the Higgs boson in its decays to two W bosons using the Run-I ATLAS dataset. This is the most precise measurement of gluon-fusion Higgs boson production and is among the most significant results attained at the LHC. The thesis provides an exceptionally clear exposition on a complicated analysis performed by a large team of researchers. Aspects of the analysis performed by the author are explained in detail; these include new methods for evaluating uncertainties on the jet binning used in the analysis and for estimating the background due to associated production of a W boson and an off-shell photon. The thesis also describes a measurement of the WW cross section, an essential background to Higgs boson production. The primary motivation of the LHC was to prove or disprove the existence of the Higgs boson. In 2012, CERN announced this discovery and the resultant ATLAS publication contained three decay channels: gg, ZZ, and WW.

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 Higgs Boson Search in the H WW Lnylny Channel Using Neural Networks with the ATLAS Detector at 7 TeV written by Georg Sartisohn and published by . This book was released on 2012 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Search for the Higgs Boson in the Process H 2 ZZ 2 llv Produced Via Vector boson Fusion with the ATLAS Detector written by Clive Andrew Edwards and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The search potential of a Standard Model Higgs boson in the Vector Boson Fusion production mechanism with Higgs boson decaying to two leptons and two neutrinos via decay to two Z bosons with the ATLAS detector is investigated. The ATLAS detector is a general purpose detector in operation at CERN measuring proton-proton collisions produced by the Large Hadron Collider. This channel has been shown to have high sensitivity at large Higgs mass, where large amounts of missing energy in the signal provide good discrimination over expected backgrounds. This work takes a first look at whether the sensitivity of this channel may be improved using the remnants of the vector boson fusion process to pro- vide extra discrimination, particularly at lower mass where sensitivity of the main analysis is reduced because of lower missing energy. Simulated data samples at centre of mass energy 7 Te V are used to derive signal significances over the mass range between 200-600 Ge V / c2. Because of varying signal properties with mass, a low and a high mass event selection were developed and optimized. A comparison between simulated and real data (collected in 2010) is made of variables used in the analysis and the effect of pileup levels corresponding to those in the 2010 data is investigated. Possible methods to estimate some of the main backgrounds to this search are described and discussed. The impact • of important theoretical and detector related systematics are taken into account. Final results are presented in the form of 95 % Confidence Level exclusion limits on the signal cross section relative to the SM prediction as a function of Higgs boson mass, based on an integrated luminosity of 33.4 pb -1 of data collected during 2010.

Download or read book Search for the SM Higgs Boson in the W Z H Channel with H Bb Using the ATLAS Detector at the LHC written by Garoé González Parra and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Search for Nothing written by William Balunas and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a search for invisible decays of the Higgs boson using the vector boson fusion channel. This uses 36 fb-1 of proton-proton collision data at [square root] s = 13 TeV using the ATLAS detector at the Large Hadron Collider. The experimental methods for understanding the signal and background processes as well as detector effects are described in detail. The search is carried out in several regions defined by kinematic requirements on the final-state objects, and the observed event yields are used in a profile-likelihood fit in order to constrain the backgrounds. The results are interpreted using a modified frequentist method and are found to be consistent with the Standard Model expectations. An upper limit of 34% (28% expected) at 95% C.L. is placed on the invisible branching ratio of the Higgs boson. Re-interpretation of these results in terms of dark matter is also discussed, in the context of the Higgs portal and other simplified models.

Download or read book Measurement of the Mass of the Higgs Boson in the H ZZ 4l Channel at the ATLAS Detector written by Thomas Powell and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Search for a Standard Model Higgs Boson in the ZH Vvbb Channel with the ATLAS Detector written by Matthew Jackson 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 the Higgs Boson in the TtH H Bb Channel and the Identification of Jets Containing Two B Hadrons with the ATLAS Experiment written by Royer Edson Ticse Torres and published by . This book was released on 2016 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: In July 2012, CERN announced the discovery of the Higgs boson, the last missing piece of the Standard Model (SM). The Higgs boson was observed in different channels. Precise measurement of its properties is now very important to investigate for possible deviations from the SM. This thesis presents a search for the Higgs boson produced in association with top quarks and decaying to a b quark pair, the ttH(H→bb) channel, using proton-proton collisions at √s = 13 TeV, collected with the ATLAS detector in 2015 and 2016. This document details in particular the full reconstruction of the ttH(H→bb) system and the discrimination between signal and the main background, tt+jets. The ttbb is a subset of the tt+jets backgrounds recent studies show that there is a large fraction of ttbb events with jets containing two b-hadrons. A new algorithm has been developed to discriminate such jets from single b-hadrons jets. The description of this tool is presented in this thesis.

Download or read book Search for a Light Charged Higgs Boson in the Decay Channel H C s Using the ATLAS Detector written by Omran Trifis 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 the Higgs boson in the process H ZZ ll produced via vector Boson fusion with the ATLAS detector written by Clive Edwards and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Search for the Higgs Boson in the ZH Channel with the D zero Detector at the Fermilab Tevatron Collider written by James Matthew Heinmiller and published by . This book was released on 2006 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: This analysis describes a search for a standard model Higgs boson produced in association with a Z boson through the decay mode ZH → e+e -bb in pp collisions at s = 1.96 TeV at the Fermilab Tevatrot Collider. The data sample used in this analysis corresponds to 452 pb-1 of integrated luminosity accumulated with the DO detector. Agreement between data and standard model predictions is observed. A 95% confidence level upper exclusion limit for the sigma(pp → ZH x BR(H → bb) channel is set between 3.2--8.2 pb for Higgs masses of 105 to 145 GeV.

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 Discovery of the Higgs Boson Measurements of Higgs Boson Properties and Search for High Mass Beyond the Standard Model Scalar Particle in the Diphoton Final State with the ATLAS Detector at the Large Hadron Collider written by Hongtao Yang and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: With 4.8~$\rm{fb}^{-1}$ of proton-proton collision data collected at $\sqrt{s}=7~\rm{TeV}$ in 2011, and 5.9~$\rm{fb}^{-1}$ collected at $\sqrt{s}=8~\rm{TeV}$ in 2012 by the ATLAS detector at the Large Hadron Collider, an excess of 4.5 standard deviations from the background-only hypothesis is observed near 126.5~GeV in the diphoton invariant mass spectra. Along with the excesses observed in the $H \rightarrow ZZ^{(*)}\rightarrow \ell\ell\ell\ell$ and $H \rightarrow WW^{(*)}\rightarrow \ell\nu\ell\nu$ channels, the observation of a Higgs-like particle is established at 6.0 standard deviations level. With more data accumulated during LHC Run~1, the measurements of Higgs boson couplings and mass in the $H\to\gamma\gamma$ channel are conducted by the ATLAS experiment based on 4.5~$\rm{fb}^{-1}$ of proton-proton collisions at $\sqrt{s}=7~\rm{TeV}$ collected in 2011, and 20.3~$\rm{fb}^{-1}$ at $\sqrt{s}=8~\rm{TeV}$ collected in 2012. The combined signal strength, defined as number of observed Higgs boson decays to diphoton divided by the corresponding Standard Model prediction, is measured to be $1.17 \ ^{+0.28}_{-0.26}$ assuming the Higgs boson mass being 125.4~$\rm{GeV}$. The signal strengths for individual Higgs boson production processes are also measured, and are found to be in good consistency with the Standard Model. The mass of the Higgs boson is measured in $H\to\gamma\gamma$ channel by the ATLAS experiment to be $125.98 \pm 0.50$~\GeV. This measurement is combined with the ones from ATLAS $H \rightarrow ZZ^{(*)}\rightarrow \ell\ell\ell\ell$ as well as CMS $H\to\gamma\gamma$ and $H \rightarrow ZZ^{(*)}\rightarrow \ell\ell\ell\ell$. The Higgs boson mass measured from the combination is $125.09\pm0.24~\rm{GeV}$. With LHC center-of-mass energy increased to 13~TeV, a search for high mass Beyond the Standard Model scalar resonance is performed in the diphoton decay channel based on 15.4~$\rm{fb}^{-1}$ of proton-proton collision data collected by the ATLAS detector during 2015 and 2016. While a notable wide excess was first observed in the diphoton invariant mass spectrum from the 2015 data (3.2~$\rm{fb}^{-1}$) with mass near 750~GeV, it is not confirmed by the 2016 data with much higher statistics (12.4~$\rm{fb}^{-1}$). Limits on the production cross section times branching ratio of such resonances are set.