Search For The Higgs Boson Using High Pt Isolated Like Sign Dil Events In 1 96 Tev Proton Antiproton Collisions
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Search For The Higgs Boson Using High Pt Isolated Like Sign Dil Events In 1 96 Tev Proton Antiproton Collisions
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Author :
language : en
Publisher:
Release Date : 2005
Search For The Higgs Boson Using High Pt Isolated Like Sign Dil Events In 1 96 Tev Proton Antiproton Collisions written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with categories.
Our physics objective is to search for the neutral on using events containing a like-sign dilepton pair in the following reaction: q{bar q} 2!W{sup {+-}} H 2!W{sup {+-}} W*W* 2!l{sup {+-}}l{sup {+-}} + X. The relevant Higgs boson mass region is above 160 GeV/c2 for the Standard Model Higgs boson where the branching fraction of H 2!W*W* supersedes that of H 2!b{bar b}. The search for this signature in the region at low mass (less than 135 GeV/c2) is, however, still important because we need to investigate various Higgs boson couplings as an essential test to convince that signals are attributed to the Higgs boson production. This channel also covers the case beyond the Standard Model that the Higgs boson couples only to the gauge bosons, which is referred to as the bosophilic or fermiophobic Higgs boson. The corresponding mass region suitable to our signature is above 110 GeV/c2 where the branching fraction of H 2![gamma][gamma] is overtaken by this channel. On the experimental side, the like-sign dilepton event is one of the cleanest signature in hadron collisions. This analysis exploiting such a distinctive signature is therefore expected to have a high potential of the sensitivity for the search of the Higgs boson. The data were collected with the CDF II detector between March 2002 and September 2003, corresponding to an integrated luminosity of 193.5 pb−1. At off-line, the central region).
Search For Wh Production Using High P T Isolated Like Sign Dilepton Events In 1 96 Tev Proton Antiproton Collisions
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Author :
language : en
Publisher:
Release Date : 2009
Search For Wh Production Using High P T Isolated Like Sign Dilepton Events In 1 96 Tev Proton Antiproton Collisions written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
The thesis describes search for the neutral Higgs production associated with the W boson using high-PT isolated like-sign (LS) dilepton events in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV.
A Search For The Higgs Boson And A Search For Dark Matter Particle With Jets And Missing Transverse Energy At Collider Detector At Fermilab
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Author :
language : en
Publisher:
Release Date : 2013
A Search For The Higgs Boson And A Search For Dark Matter Particle With Jets And Missing Transverse Energy At Collider Detector At Fermilab written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
Finding the standard model Higgs boson and discovering beyond-standard model physics phenomena have been the most important goals for the high-energy physics in the last decades. In this thesis, we present two such searches. First is the search for the low mass standard model Higgs boson produced in association with a vector boson; second is the rst search for a dark-matter candidate (D) produced in association with a top quark (t) in particle colliders. We search in events with energetic jets and large missing transverse energy { a signature characterized by complicated backgrounds { in data collected by the CDF detector with proton-antiproton collisions at p s = 1:96 TeV. We discuss the techniques that have been developed for background modeling, for discriminating signal from background, and for reducing background resulting from detector e ects. In the Higgs search, we report the 95% con dence level upper limits on the pro- duction cross section across masses of 90 to 150 GeV/c2. The expected limits are improved by an average of 14% relative to the previous analysis. The Large Hadron Collider experiments reported a Higgs-like particle with mass of 125 GeV/c2 by study- ing the data collected in year 2011/12. At a Higgs boson mass of 125 GeV/c2, our observed (expected) limit is 3.06 (3.33) times the standard model prediction, corre- sponding to one of the most sensitive searches to date in this nal state. In the dark matter search, we nd the data are consistent with the standard model prediction, thus set 95% con dence level upper limits on the cross section of the process p p! t + D as a function of the mass of the dark-matter candidate. The xviii upper limits are approximately 0.5 pb for a dark-matter particle with masses in the range of 0 150 GeV/c2.
Search For The Higgs Boson Produced In Association With A W Boson At Cdf Run Ii
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Author : Jason Michael Slaunwhite
language : en
Publisher:
Release Date : 2009
Search For The Higgs Boson Produced In Association With A W Boson At Cdf Run Ii written by Jason Michael Slaunwhite and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with Higgs bosons categories.
Abstract: We present a search for standard model Higgs boson production in association with a W boson in proton-antiproton collisions at a center of mass energy of 1.96 TeV. WH candidate events have a signature of a single lepton, missing transverse energy, and two jets. The search looks for candidate events in approximately 2.7 fb−1 of data recorded with the CDF II detector. The high transverse momentum (high-pT) lepton (electron or muon) in the events provides a distinct signature for triggering and most of the events in the dataset come from high-pT lepton triggers. Our analysis improves on prior searches by including events recorded on the Missing Transverse Energy (MET) plus 2 jets trigger with a lepton reconstructed as an isolated high-pT charged particle. We increase the sample purity by identifying ("tagging") long-lived b-hadrons in jets. A neural network combines distinguishing kinematic information into a function optimized for WH sensitivity. The neural network output distributions are consistent with the standard model background expectations and we set limits upper limits on the rate of Higgs production. We set 95% confidence level upper limits on the WH production cross section times branching ratio for Higgs masses from 100 to 150 GeV/c2 and express our results as a ratio of the experimental limit to the theoretical Standard Model production rate. Our limits range from 3.6 (4.3 expected) to 61.1 (43.2 expected) for Higgs masses from 100 to 150 GeV/c2, respectively.
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Author :
language : en
Publisher:
Release Date : 1981
written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1981 with categories.
Search For The Standard Model Higgs Boson In The H Zz L L Qq Decay Channel At Cms
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Author : Francesco Pandolfi
language : en
Publisher: Springer Science & Business Media
Release Date : 2013-08-15
Search For The Standard Model Higgs Boson In The H Zz L L Qq Decay Channel At Cms written by Francesco Pandolfi and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-08-15 with Science categories.
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.
Search For Higgs Boson Production In Association With The W Boson In 1 96 Tev Proton Antiproton Collisions
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Author :
language : en
Publisher:
Release Date : 2005
Search For Higgs Boson Production In Association With The W Boson In 1 96 Tev Proton Antiproton Collisions written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with categories.
A search for the Standard Model Higgs boson was carried out in WH 2!l[nu]b{bar b} process in p{bar p} collisions at a center of mass energy of 1.96 TeV, where W, H, l, [nu], b and p denote either a W or W− boson, Higgs boson, lepton (electron or muon), neutrino, bottom quark and proton, respectively. The data were collected with the Collider Detector at Fermilab from February 2002 to August 2004. The corresponding integrated luminosity is 319 pb−1. We select events containing a single high-p{sub T} electron or muon, a large imbalance of the total transverse energy from a neutrino and two b quark jets. The main backgrounds are the W + light flavor/gluon jets and W + heavy flavor jets processes. Requiring the secondary vertex b-tagging enables us to reject the W + light flavor/gluon jets events effectively. After all event selections, they observe 187 events which is in agreement with the Standard Model background expectation of 175.2 ± 26.3 events, and there is no significant excess originating from the Higgs boson in the reconstructed dijet invariant mass distribution. They thus set a 95% confidence level upper limit on the production cross section times branching ratio decaying into bb, [sigma](p{bar p} 2!W H) x Br(H 2!b{bar b}). The detection efficiency for the W H events, which is necessary for calculating the upper limit, is determined by the Monte Carlo except for the lepton identification efficiency, the lepton trigger efficiency and the b-tagging efficiency which are estimated from the CDF real data. The resultant 95% confidence level upper limits are 10.0 pb to 2.8 pb using at least one b-tagging method and 9.7 pb to 6.6 pb using double b-tagging method for the Higgs boson mass region 110 GeV/c2 to 150 GeV/c2, where the Standard Model prediction is approximately one or two order of magnitude lower than the results.
Search For A High Mass Higgs Boson Produced In Proton Anti Proton Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2011
Search For A High Mass Higgs Boson Produced In Proton Anti Proton Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
In this Thesis a search for Higgs boson production has been performed analysing data gathered by the Collider Detector at Fermilab (CDF) from proton-antiproton (p$\bar{p}$) collisions at the center of mass energy √s = 1.96 TeV. Event selection has been optimized on Higgs decaying into W+W- bosons in order to reconstruct final states with two charged leptons formed by either an electron and a tau or a muon and a tau focusing on taus decaying into hadrons. No evidence of Higgs production has been found analysing 4.8 fb-1 of data and an up- per limit has been set on the production cross section as a function of the mass mH in the range from 130 to 200 GeV/c2 with a 95% Confidence Level. For a Higgs mass hypothesis of 160 GeV/c2 the observed limit is 33.5 times the Standard Model predicted cross section [sigma]SM while the expected upper limit for the same mass is 19.6×[sigma]SM. The high recorded luminosity along with the development of new analysis techniques are expected to improve the CDF sensitivity to the search for Higgs boson with hadronic taus reconstructed in the final state, in the mass range 130 to 200 GeV/c2.
A Search For Supersymmetric Higgs Bosons In The Di Tau Decay Mode In Proton Anti Proton Collisions At 1 8 Tev
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Author : Amy Lynn Connolly
language : en
Publisher:
Release Date : 2003
A Search For Supersymmetric Higgs Bosons In The Di Tau Decay Mode In Proton Anti Proton Collisions At 1 8 Tev written by Amy Lynn Connolly and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003 with categories.
A search for directly produced Supersymmetric Higgs Bosons has been performed in the di-tau decay channel in 86.3 {+-} 3.5 pb{sup -1} of data collected by CDF during Run1b at the Tevatron. They search for events where one tau decays to an electron and the other tau decays hadronically. They perform a counting experiment and set limits on the cross section for Higgs production in the high tan {beta} region of the m{sub A}-tan {beta} plane. For a benchmark parameter space point where m{sub A} = 100 and tan {beta} = 50, they set a 95% confidence level upper limit at 891 pb compared to the theoretically predicted cross section of 122 pb. For events where the tau candidates are not back-to-back, they utilize a di-tau mass reconstruction technique for the first time on hadron collider data. Limits based on a likelihood binned in di-tau mass from non-back-to-back events alone are weaker than the limits obtained from the counting experiment using the full di-tau sample.
A Search For Supersymmetric Higgs Bosons In The Di Tau Decay Mode In Proton Anti Proton Collisions At 1 8 Tev
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Author :
language : en
Publisher:
Release Date : 2005
A Search For Supersymmetric Higgs Bosons In The Di Tau Decay Mode In Proton Anti Proton Collisions At 1 8 Tev written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with categories.
A search for directly produced Supersymmetric Higgs Bosons has been performed in the di-tau decay channel in 86.3 [+-] 3.5 pb[sup -1] of data collected by CDF during Run1b at the Tevatron. The authors search for events where one tau decays to an electron and the other tau decays hadronically. They perform a counting experiment and set limits on the cross section for Higgs production in the high tan [beta]region of the m[sub A]-tan [beta] plane. For a benchmark parameter space point where m[sub A] = 100 and tan [beta] = 50, they set a 95% confidence level upper limit at 891 pb compared to the theoretically predicted cross section of 122 pb. For events where the tau candidates are not back-to-back, they utilize a di-tau mass reconstruction technique for the first time on hadron collider data. Limits based on a likelihood binned in di-tau mass from non-back-to-back events alone are weaker than the limits obtained from the counting experiment using the full di-tau sample.