Download or read book Search for the Standard Model Higgs Boson in the Decay Mode H WW Lnulnu written by and published by . This book was released on 2009 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: The question of the nature and principles of the universe and our place in it is the driving force of science since Mesopotamian astronomers glanced for the first time at the starry sky and Greek atomism has been formulated. During the last hundred years modern science was able to extend its knowledge tremendously, answering many questions, opening entirely new fields but as well raising many new questions. Particularly Astronomy, Astroparticle Physics and Particle Physics lead the race to answer these fundamental and ancient questions experimentally. Today it is known that matter consists of fermions, the quarks and leptons. Four fundamental forces are acting between these particles, the electromagnetic, the strong, the weak and the gravitational force. These forces are mediated by particles called bosons. Our confirmed knowledge of particle physics is based on these particles and the theory describing their dynamics, the Standard Model of Particles. Many experimental measurements show an excellent agreement between observation and theory but the origin of the particle masses and therefore the electroweak symmetry breaking remains unexplained. The mechanism proposed to solve this issue involves the introduction of a complex doublet of scalar fields which generates the masses of elementary particles via their mutual interactions. This Higgs mechanism also gives rise to a single neutral scalar boson with an unpredicted mass, the Higgs boson. During the last twenty years several experiments have searched for the Higgs boson but so far it escaped direct observation. Nevertheless these studies allow to further constrain its mass range. The last experimental limits on the Higgs mass have been set in 2001 at the LEP collider, an electron positron machine close to Geneva, Switzerland. The lower limit set on the Higgs boson mass is m{sub H}> 114.4 GeV/c2 and remained for many years the last experimental constraint on the Standard Model Higgs Boson due to the shutdown of the LEP collider and the experimental challenges at hadron machines as the Tevatron. This thesis was performed using data from the D0 detector located at the Fermi National Accelerator Laboratory in Batavia, IL. Final states containing two electrons or a muon and a tau in combination with missing transverse energy were studied to search for the Standard Model Higgs boson, utilizing up to 4.2 fb−1 of integrated luminosity. In 2008 the CDF and D0 experiments in a combined effort were able to reach for the first time at a hadron collider the sensitivity to further constrain the possible Standard Model Higgs boson mass range. The research conducted for this thesis played a pivotal role in this effort. Improved methods for lepton identification, background separation, assessment of systematic uncertainties and new decay channels have been studied, developed and utilized. Along with similar efforts at the CDF experiment these improvements led finally the important result of excluding the presence of a Standard Model Higgs boson in a mass range of m{sub H} = 160-170 GeV/c2 at 95% Confidence Level. Many of the challenges and methods found in the present analysis will probably in a similar way be ingredients of a Higgs boson evidence or discovery in the near future, either at the Tevatron or more likely at the soon starting Large Hadron Collider (LHC). Continuing to pursue the Higgs boson we are looking forward to many exciting results at the Tevatron and soon at the LHC. In Chapter 2 an introduction to the Standard Model of particle physics and the Higgs mechanism is given, followed by a brief outline of existing theoretical and experimental constraints on the Higgs boson mass before summarizing the Higgs boson production modes. Chapter 3 gives an overview of the experimental setup. This is followed by a description of the reconstruction of the objects produced in proton-antiproton collisions in Chapter 4 and the necessary calorimeter calibrations in Chapter 5. Chapter 6 follows with an explanation of the phenomenology of the proton-antiproton collisions and the data samples used. In Chapter 7 the search for the Standard Model Higgs boson using a di-electron final state is discussed, followed by the analysis of the final states using muons and hadronic decaying taus in Chapter 8. Finally a short outlook for the prospects of Higgs boson searches is given in Chapter 9.
Download or read book Search for the Standard Model Higgs Boson in the Decay Mode H W 1hn W 1hn L 1hn n63l 1hn n63 l Nu L Nu at the D Experiment written by Björn Penning and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for the Standard Model Higgs Boson in the H to WW to ell nu ell nu Decay Mode With 4 7 Fb of ATLAS Data at sqrt s written by and published by . This book was released on 2014 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for the Standard Model Higgs Boson in the Decay Mode H W W L l l Nu L Nu at the D Experiment written by Björn Penning and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for the Standard Model Higgs Boson in the Decay Mode H u2192 W W u2192 L vl v written by and published by . This book was released on 2009 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: The question of the nature and principles of the universe and our place in it is the driving force of science since Mesopotamian astronomers glanced for the first time at the starry sky and Greek atomism has been formulated. During the last hundred years modern science was able to extend its knowledge tremendously, answering many questions, opening entirely new fields but as well raising many new questions. Particularly Astronomy, Astroparticle Physics and Particle Physics lead the race to answer these fundamental and ancient questions experimentally. Today it is known that matter consists of fermions, the quarks and leptons. Four fundamental forces are acting between these particles, the electromagnetic, the strong, the weak and the gravitational force. These forces are mediated by particles called bosons. Our confirmed knowledge of particle physics is based on these particles and the theory describing their dynamics, the Standard Model of Particles. Many experimental measurements show an excellent agreement between observation and theory but the origin of the particle masses and therefore the electroweak symmetry breaking remains unexplained. The mechanism proposed to solve this issue involves the introduction of a complex doublet of scalar fields which generates the masses of elementary particles via their mutual interactions. This Higgs mechanism also gives rise to a single neutral scalar boson with an unpredicted mass, the Higgs boson. During the last twenty years several experiments have searched for the Higgs boson but so far it escaped direct observation. Nevertheless these studies allow to further constrain its mass range. The last experimental limits on the Higgs mass have been set in 2001 at the LEP collider, an electron positron machine close to Geneva, Switzerland. The lower limit set on the Higgs boson mass is mH > 114.4 GeV/c2 and remained for many years the last experimental constraint on the Standard Model Higgs Boson due to the shutdown of the LEP collider and the experimental challenges at hadron machines as the Tevatron. This thesis was performed using data from the D0 detector located at the Fermi National Accelerator Laboratory in Batavia, IL. Final states containing two electrons or a muon and a tau in combination with missing transverse energy were studied to search for the Standard Model Higgs boson, utilizing up to 4.2 fb-1 of integrated luminosity. In 2008 the CDF and D0 experiments in a combined effort were able to reach for the first time at a hadron collider the sensitivity to further constrain the possible Standard Model Higgs boson mass range. The research conducted for this thesis played a pivotal role in this effort. Improved methods for lepton identification, background separation, assessment of systematic uncertainties and new decay channels have been studied, developed and utilized. Along with similar efforts at the CDF experiment these improvements led finally the important result of excluding the presence of a Standard Model Higgs boson in a mass range of mH = 160-170 GeV/c2 at 95% Confidence Level. Many of the challenges and methods found in the present analysis will probably in a similar way be ingredients of a Higgs boson evidence or discovery in the near future, either at the Tevatron or more likely at the soon starting Large Hadron Collider (LHC). Continuing to pursue the Higgs boson we are looking forward to many exciting results at the Tevatron and soon at the LHC. In Chapter 2 an introduction to the Standard Model of particle physics and the Higgs mechanism is given, followed by a brief outline of existing theoretical and experimental constraints on the Higgs boson mass before summarizing the Higgs boson production modes. Chapter 3 gives an overview of the experimental setup. This is followed by a description of the reconstruction of the objects produced in proton-antiproton collisions in Chapter 4 and the necessary calorim...
Download or read book Search for the Standard Model Higgs Boson in Proton antiproton Interactions with the Decay Mode H Going to W W Going to Muon Neutrino Muon Neutrino at the D0 Experiment written by Dale Morgan Johnston and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for the Standard Model Higgs Boson in the H W W L l decay Mode in Proton proton Collisions at s written by Evelyn Schmidt 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 First Search for the Standard Model Higgs Boson Using the Semileptonic Decay Channel written by Shannon Maura Zelitch and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for the Standard Model Higgs Boson in the H ZZ L L Qq Decay Channel at CMS written by Francesco Pandolfi and published by . This book was released on 2013-09-30 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for the H Bb Decay Mode of the Standard Model Higgs Boson in Associated Production with a Vector Boson in Proton proton Collisions at s written by Jan Therhaag and published by . This book was released on 2014 with total page 163 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for the Standard Model Higgs Boson in the H ZZ l l qq Decay Channel at CMS written by Francesco Pandolfi and published by Springer Science & Business Media. This book was released on 2013-08-15 with total page 137 pages. Available in PDF, EPUB and Kindle. Book excerpt: The theoretical foundations of the Standard Model of elementary particles relies on the existence of the Higgs boson, a particle which has been revealed for the first time by the experiments run at the Large Hadron Collider (LHC) in 2012. As the Higgs boson is an unstable particle, its search strategies were based on its decay products. In this thesis, Francesco Pandolfi conducted a search for the Higgs boson in the H → ZZ → l + l - qq Decay Channel with 4.6 fb -1 of 7 TeV proton-proton collision data collected by the Compact Muon Solenoid (CMS) experiment. The presence of jets in the final state poses a series of challenges to the experimenter: both from a technical point of view, as jets are complex objects and necessitate of ad-hoc reconstruction techniques, and from an analytical one, as backgrounds with jets are copious at hadron colliders, therefore analyses must obtain high degrees of background rejection in order to achieve competitive sensitivity. This is accomplished by following two directives: the use of an angular likelihood discriminant, capable of discriminating events likely to originate from the decay of a scalar boson from non-resonant backgrounds, and by using jet parton flavor tagging, selecting jets compatible with quark hadronization and discarding jets more likely to be initiated by gluons. The events passing the selection requirements in 4.6 fb -1 of data collected by the CMS detector are examined, in the search of a possible signal compatible with the decay of a heavy Higgs boson. The thesis describes the statistical tools and the results of this analysis. This work is a paradigm for studies of the Higgs boson with final states with jets. The non-expert physicists will enjoy a complete and eminently readable description of a proton-proton collider analysis. At the same time, the expert reader will learn the details of the searches done with jets at CMS.
Download or read book Search for the H bb decay mode of the standard model higgs boson in associated production with a vector boson in proton proton collisions at s written by and published by . This book was released on 2014 with total page 163 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for the Standard Model Higgs Boson in P bar p Interactions with the Decay Mode H u2192 W W u2192 v v at the D Experiment written by and published by . This book was released on 2010 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for the standard model Higgs boson in p$ar{p}$ collisions resulting in two muons and large missing transverse energy is presented. The analysis uses 4.2 fb-1 of integrated luminosity at a center-of-mass energy of √s = 1.96 TeV collected between April 2002 and December 2008 with the D0 detector at the Fermilab Tevatron collider. No significant excess above the background estimation is observed and limits are derived on Higgs boson production.
Download or read book Search for the Standard Model Higgs Boson in E tau Final States written by and published by . This book was released on 2013 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presented in this dissertation is a search for the standard model (SM) Higgs boson using the DØ detector at Fermilab in Batavia, IL. The SM is a fantastically accurate theory describing the fundamental interactions and particles of the Universe. The only undiscovered particle in the SM is the Higgs boson, which is hypothesized to be responsible for electroweak symmetry breaking and giving mass to all other particles. Considered in this search is the process H + X → e[tau]hjj, where e is an electron, [tau]h is the hadronic decay of a tau, and j is a jet, using p $\bar{p}$ collisions at center of mass energy√s = 1.96 TeV. This search includes three production modes: associated production, gluon fusion and vector boson fusion. It also utilizes two decay channels: H→ [tau][tau] and H → WW. A new technique, dubbed the Global Boosted Decision Tree, is introduced which offers a means of providing continuity to a multivariate search as a function of a particular parameter, in this case, the mass of the Higgs boson. The observed (expected) limit on the ratio of cross section times branching fraction to the SM at 95% confidence level is 14.6 (16.0) at mH = 125 GeV. This result is combined with the related channel H + X → [mu][tau]hjj and produced an observed (expected) limit of 9.0 (11.3) at mH = 125 GeV.
Download or read book Search for the Standard Model Higgs Boson in the H WW Lepton neutrino q qbar Decay Channel written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a search for the standard model Higgs boson (H) in ppbar collisions at sqrt{s}=1.96 TeV in events containing a charged lepton (ell), missing transverse energy, and at least two jets, using 5.4 fb-̂1 of integrated luminosity recorded with the D0 detector at the Fermilab Tevatron Collider. This analysis is sensitive primarily to Higgs bosons produced through the fusion of two gluons or two electroweak bosons, with subsequent decay H->WW->ell+nu+q'qbar, where ell is an electron or muon. The search is also sensitive to contributions from other production channels, such as WH->ell+nu+bbbar In the absence of signal, we set limits at the 95% C.L. on the cross section for H production sigma(ppbar->H+X) in these final states. For a mass of MH=160 GeV, the limit is a factor of 3.9 larger than the cross section in the standard model, and consistent with expectation.
Download or read book Searches for the Standard Model Higgs Boson in the Leptonic Decay Channels written by Jin Yamamoto and published by . This book was released on 2002 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Standard Model Higgs Boson written by M.B. Einhorn and published by Elsevier. This book was released on 2012-12-02 with total page 401 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Standard Model of electroweak and strong interactions contains a scalar field which permeates all of space and matter, and whose properties provide the explanation of the origin of the masses. Commonly referred to as the Higgs field, it assumes in the physical vacuum a non-vanishing classical expectation value to which the masses of not only the vector bosons, but all the other known fundamental particles (quarks and leptons) are proportional. This volume presents a concise summary of the phenomenological properties of the Higgs boson.
