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Search For The Higgs Boson In Events With Missing Transverse Energy And B Quark Jets Produced In Proton Antiproton Collisions At Su
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Book Synopsis Search for the Higgs Boson in Events with Missing Transverse Energy and B Quark Jets Produced in Proton-antiproton Collisions at S**1/2 by :
Download or read book Search for the Higgs Boson in Events with Missing Transverse Energy and B Quark Jets Produced in Proton-antiproton Collisions at S**1/2 written by and published by . This book was released on 2008 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: We search for the standard model Higgs boson produced in association with an electroweak vector boson in events with no identified charged leptons, large imbalance in transverse momentum, and two jets where at least one contains a secondary vertex consistent with the decay of b hadrons. We use ≈1 fb−1 integrated luminosity of p{bar p} collisions at √s = 1.96 TeV recorded by the CDF II experiment at the Tevatron. We find 268 (16) single (double) b-tagged candidate events, where 248 ± 43 (14.4 ± 2.7) are expected from standard model background processes. We place 95% confidence level upper limits on the Higgs boson production cross section for several Higgs boson masses ranging from 110 GeV/c2 to 140 GeV/c2. For a mass of 115 GeV/c2 the observed (expected) limit is 20.4 (14.2) times the standard model prediction.
Book Synopsis Search for the Higgs Boson in Events with Missing Transverse Energy and B Quark Jets Produced in Proton-antiproton Collisions at S**ư by :
Download or read book Search for the Higgs Boson in Events with Missing Transverse Energy and B Quark Jets Produced in Proton-antiproton Collisions at S**ư written by and published by . This book was released on 2008 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: We search for the standard model Higgs boson produced in association with an electroweak vector boson in events with no identified charged leptons, large imbalance in transverse momentum, and two jets where at least one contains a secondary vertex consistent with the decay of b hadrons. We use ≈1 fb−1 integrated luminosity of p{bar p} collisions at √s = 1.96 TeV recorded by the CDF II experiment at the Tevatron. We find 268 (16) single (double) b-tagged candidate events, where 248 ± 43 (14.4 ± 2.7) are expected from standard model background processes. We place 95% confidence level upper limits on the Higgs boson production cross section for several Higgs boson masses ranging from 110 GeV/c2 to 140 GeV/c2. For a mass of 115 GeV/c2 the observed (expected) limit is 20.4 (14.2) times the standard model prediction.
Book Synopsis Search for the Standard Model Higgs Boson in Missing Transverse Energy and B-quark Final States Using Proton-antiproton Collisions at 1.96 TeV by : Tyler McMillan Dorland
Download or read book Search for the Standard Model Higgs Boson in Missing Transverse Energy and B-quark Final States Using Proton-antiproton Collisions at 1.96 TeV written by Tyler McMillan Dorland and published by . This book was released on 2011 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1990 with total page 1044 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Search for the Higgs Boson Using Neural Networks in Events with Missing Energy and \boldit{b}-quark Jets in $p\bar P$ Collisions at $\sqrt{s} by :
Download or read book A Search for the Higgs Boson Using Neural Networks in Events with Missing Energy and \boldit{b}-quark Jets in $p\bar P$ Collisions at $\sqrt{s} written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We report on a search for the standard model Higgs boson produced in association with a W or Z boson in p{bar p} collisions at (square root)s = 1.96 TeV recorded by the CDF II experiment at the Tevatron in a data sample corresponding to an integrated luminosity of 2.1 fb−1. We consider events which have no identified charged leptons, an imbalance in transverse momentum, and two or three jets where at least one jet is consistent with originating from the decay of a b hadron. We find good agreement between data and predictions. We place 95% confidence level upper limits on the production cross section for several Higgs boson masses ranging from 110 GeV/c2 to 150 GeV/c2. For a mass of 115 GeV/c2 the observed (expected) limit is 6.9 (5.6) times the standard model prediction.
Book Synopsis Search for the Standard Model Higgs Boson in Missing Transverse Energy and $b$-quark Final States Using Proton-Antiproton Collisions at 1.96 TeV. by :
Download or read book Search for the Standard Model Higgs Boson in Missing Transverse Energy and $b$-quark Final States Using Proton-Antiproton Collisions at 1.96 TeV. written by and published by . This book was released on 2011 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for the standard model Higgs boson is performed in 6.4 fb−1 of p{bar p} collisions at √s = 1.96 TeV, collected with the D0 detector during Run II of the Fermilab Tevatron. The final state considered is a pair of jets originating from b quarks and missing transverse energy, as expected from p{bar p} → ZH → [nu]{bar [nu]}b{bar b} production. The search is also sensitive to the WH → l{nu}b{bar b} channel, where the charged lepton is not identified. Boosted decision trees are used to discriminate signal from background. Good agreement is observed between data and expected backgrounds, and a limit is set at 95% C.L. on the section multiplied by branching fraction of (p{bar p} → (Z/W)H) x (H → b{bar b}). For a Higgs boson mass of 115 GeV, the observed limit is a factor of 3.5 larger than the value expected from the standard model.
Book Synopsis Search for the Higgs Boson Decaying to a B-quark Pair Produced in Association with a W Boson Using Missing Transverse Energy Triggered Events at ATLAS by : Benedict Marc Miller Allbrooke
Download or read book Search for the Higgs Boson Decaying to a B-quark Pair Produced in Association with a W Boson Using Missing Transverse Energy Triggered Events at ATLAS written by Benedict Marc Miller Allbrooke and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Search for Higgs Boson Production in Association with the W Boson in 1.96-TeV Proton-Antiproton Collisions by :
Download or read book Search for Higgs Boson Production in Association with the W Boson in 1.96-TeV Proton-Antiproton Collisions written by and published by . This book was released on 2005 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Search for Higgs Boson Production in Proton-antiproton Collisions at {u221A}s by :
Download or read book Search for Higgs Boson Production in Proton-antiproton Collisions at {u221A}s written by and published by . This book was released on 2006 with total page 139 pages. Available in PDF, EPUB and Kindle. Book excerpt: We performed a search for Standard Model Higgs boson production in association with W boson (p$ar{p}$ → W±H → lvb$ar{b}$) in p$ar{p}$ collisions at √s = 1.96 TeV. The search uses the data collected between February 2002 and February 2006 at Collider Detector at Fermilab (CDF), which corresponds to an integrated luminosity of about 1 fb-1. The experimental final state of WH → lvb$ar{b}$ process is lepton (e±/?±), missing transverse energy and two jets. The largest background in lepton+jets events is W+light flavor process, therefore the identification of jets as b-jets reduces this kind of background significantly. We used displaced SECondary VerTeX b-tagging (SECVTX) technique, which utilizes the signature that b-jets have secondary vertex displaced away from primary vertex because of the long life time of B-mesons. However, there is still much contamination in SECVTX b-tagged jets. Finite resolution of secondary vertex tracking measurements results in false tags, and c-jets are also identified as b-jets due to the long life time of D-mesons frequently. For the purpose of increasing the purity of the SECVTX b-tagged jets, we applied Neural Network to SECVTX tagged jets for the first time by using secondary vertex variables and some variables independent of it. Neural Network filter rejects 65% of light flavor jets and 50% of c-jets from the SECVTX tagged jets. We improved the sensitivity of the Higgs boson signal search by 10% with Neural Network b-tagging technique. Events with one high pT electron or muon, large missing transverse energy and either single SECVTX b-tagged jet which passes the Neural Network filter or at least two SECVTX b-tagged jets are selected. The number of selected events and dijet mass distributions are consistent with the Standard Model background expectations. Therefore we set an upper limit on ?(p$ar{p}$ → WH) • Br(H → b$ar{b}$) as 3.9 to 1.3 for Higgs boson mass from 110 to 150 GeV/c2 at 95% confidence level (C.L.). The upper limit obtained from WH → lvb$ar{b}$ process with 1 fb-1 is far away from the Standard Model Higgs boson production expectation by a factor of 20 to 100 as a function of Higgs boson mass. To obtain stronger constraint on the Higgs boson production, we combined the upper limits obtained in processes of ZH → ?$ar{v}$b$ar{b}$, ZH → l$ar{ℓ}$b$ar{b}$ and gg → H → W+W- → l$ar{ℓ}$v$ar{v}$ at CDF. The combination of different channels gives a constraint on the ratio of 95% confidence level upper limit divided by the Standard Model prediction ((? • Br)95/(? • Br)SM), which results in the ratio as 10 to 40 for Higgs boson mass between 110 and 200 GeV/c2. Finally, the combination of Higgs boson searches between CDF and D0 is also performed. The resulting constraint on (? • Br)95/(? • Br)SM is about 4 to 10 for Higgs boson mass between 110 and 200 GeV/c2.
Book Synopsis Search for the Higgs Boson Produced in Association with a W Boson at CDF Run II by : Jason Michael Slaunwhite
Download or read book Search for the Higgs Boson Produced in Association with a W Boson at CDF Run II written by Jason Michael Slaunwhite and published by . This book was released on 2009 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book การผลิตโซเดียมคลอไรด์ written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Search for H ---] B Anti-b Produced in Association with W Bosons in P Anti-p Collisions at S**1/2 by :
Download or read book Search for H ---] B Anti-b Produced in Association with W Bosons in P Anti-p Collisions at S**1/2 written by and published by . This book was released on 2005 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors present a search for the standard model Higgs boson decaying into b{bar b} and produced in association with W bosons in p{bar p} collisions at √s = 1.96 TeV. This search uses 320 pb−1 of the dataset accumulated by the upgraded Collider Detector at Fermilab. Events are selected that have a high-transverse momentum electron or muon, missing transverse energy, and two jets, at least one of which is consistent with the hadronization of a b quark. Both the number of events and the dijet mass distribution are consistent with standard model background expectations, and they set 95% confidence level upper limits on the production cross section times branching ratio for the Higgs boson or any new particle with similar decay kinematics. These upper limits range from 10 pb for m{sub H} = 110 GeV/c2 to 3 pb for m{sub H} = 150 GeV/c2.
Book Synopsis Search for the Standard Model Higgs Boson Produced in Association with a W Boson in the Isolated-track Charged-lepton Channel Using the Collider Detector at Fermilab by :
Download or read book Search for the Standard Model Higgs Boson Produced in Association with a W Boson in the Isolated-track Charged-lepton Channel Using the Collider Detector at Fermilab written by and published by . This book was released on 2011 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Higgs boson is the only elementary particle predicted by the Standard Model (SM) that has not yet been observed experimentally. If it exists, it explains the spontaneous electroweak symmetry breaking and the origin of mass for gauge bosons and fermions. We test the validity of the SM by performing a search for the associated production of a Higgs boson and a W boson in the channel where the Higgs boson decays to a bottom-antibottom quark pair and the W boson decays to a charged lepton and a neutrino (the WH channel). We study a dataset of proton-antiproton collisions at a centre-of-mass energy √s = 1.96 TeV provided by the Tevatron accelerator, corresponding to an integrated luminosity of 5.7 fb−1, and recorded using the Collider Detector at Fermilab (CDF).We select events consistent with the signature of exactly one charged lepton (electron or muon), missing transverse energy due to the undetected neutrino (MET) and two collimated streams of particles (jets), at least one of which is required to be identified as originating from a bottom quark. We improve the discrimination of Higgs signal from backgrounds through the use of an artificial neural network. Using a Bayesian statistical inference approach, we set for each hypothetical Higgs boson mass in the range 100-150 GeV/c2 with 5 GeV/c2 increments a 95% credibility level (CL) upper limit on the ratio between the Higgs production cross section times branching fraction and the SM prediction. Our main original contributions are the addition of a novel charged lepton reconstruction algorithm with looser requirements (ISOTRK) with respect the electron or muon tight criteria (TIGHT), as well as the introduction of a novel trigger-combination method that allows to maximize the event yield while avoiding trigger correlations and that is used for the ISOTRK category. The ISOTRK candidate is a high-transverse-momentum good-quality track isolated from other activity in the tracking system and not required to match a calorimeter cluster, as for a tight electron candidate, or an energy deposit in the muon detector, as for a tight muon candidate. The ISOTRK category recovers real charged leptons that otherwise would be lost in the non-instrumented regions of the detector. This allows the reconstruction of more W boson candidates, which in turn increases the number of reconstructed WH signal candidate events, and therefore improves the sensitivity of the WH search. For the TIGHT charged lepton categories, we employ charged-lepton-dedicated triggers to improve the rate of WH signal acceptance during data taking. Since there is no ISOTRK-dedicated trigger at CDF, for the ISOTRK charged lepton category we employ three MET-plus-jets-based triggers. For each trigger we first identify the jet selection where the trigger efficiency is flat with respect to jet information (transverse energy and direction of motion in the transverse plane for the two jets in the event) and then we parametrize the trigger efficiency as a function of trigger MET. On an event-by-event basis, for each trigger we compute a trigger efficiency as a function of trigger parametrization, trigger MET, jet information, trigger prescale and information about whether the trigger is defined or not. For the ISOTRK category we combine the three triggers using a novel method, which allows the combination of any number of triggers in order to maximize the event yield while avoiding trigger correlations. On an event-by-event basis, only the trigger with the largest efficiency is used. By avoiding a logical 'OR' between triggers, the loss in the yield of events accepted by the trigger combination is compensated by a smaller and easier-to-compute corresponding systematic uncertainty. The addition of the ISOTRK charged lepton category to the TIGHT category produces an increase of 33% in the WH signal yield and a decrease of 15.5% to 19.0% in the median expected 95% CL cross-section upper limits across the entire studied Higgs mass interval. The improvement in analysis sensitivity is smaller than the improvement in signal yield because the ISOTRK category has a smaller signal over background ratio than the TIGHT category, due to the looser ISOTRK reconstruction criteria. The observed (median expected) 95% CL SM Higgs upper limits on cross section times branching ratio vary between 2.39 x SM (2.73 x SM) for a Higgs mass of 100 GeV/c2 to 31.1 x SM (31.2 x SM) for a Higgs mass of 150 GeV/c2, while the value for a 115 GeV/c2 Higgs boson is that of 5.08 x SM (3.79 x SM). The novel trigger combination method is already in use by several CDF analyses. It is applicable to any analysis that uses triggers based on MET and jets, such as supersymmetry searches at the ATLAS and CMS experiments at the Large Hadron Collider. In its most general form, the method can be used by any analysis that combines any number of different triggers.
Book Synopsis Search for the Higgs Boson in the All-Hadronic Final State Using the CDF II Detector by :
Download or read book Search for the Higgs Boson in the All-Hadronic Final State Using the CDF II Detector written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis reports the result of a search for the Standard Model Higgs boson in events containing four reconstructed jets associated with quarks. For masses below 135 GeV/c2, the Higgs boson decays to bottom-antibottom quark pairs are dominant and result primarily in two hadronic jets. An additional two jets can be produced in the hadronic decay of a W or Z boson produced in association with the Higgs boson, or from the incoming quarks that produced the Higgs boson through the vector boson fusion process. The search is performed using a sample of s = sqrt(1.96) TeV proton-antiproton collisions corresponding to an integrated luminosity of 9.45 fb-1 recorded by the CDF II detector. The data are in agreement with the background model and 95% credibility level upper limits on Higgs boson production are set as a function of the Higgs boson mass. The median expected (observed) limit for a 125 GeV/c2 Higgs boson is 11.0 (9.0) times the predicted standard model rate.
Book Synopsis Search for Charged Higgs Bosons in Decays of Top Quarks in Proton - Antiproton Collisions at S**1/2 by :
Download or read book Search for Charged Higgs Bosons in Decays of Top Quarks in Proton - Antiproton Collisions at S**1/2 written by and published by . This book was released on 2009 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this dissertation we report on the first direct search for charged Higgs bosons in decays of top quarks in p{bar p} collisions at √s = 1.96 TeV. The search uses a data sample with an integrated luminosity of 2.2 fb−1 collected by the CDF II detector at Fermilab and looks for a resonance in the invariant mass distribution of two jets in the lepton+jets sample of t{bar t} candidates. We observe no evidence of charged Higgs bosons in top quark decays; hence 95% C.L. upper limits on the branching ratio are placed at [Beta](t → H+b)
Book Synopsis Search for H ---] B Anti-b Produced in Association with W Bosons in P Anti-p Collisions at S**ư by :
Download or read book Search for H ---] B Anti-b Produced in Association with W Bosons in P Anti-p Collisions at S**ư written by and published by . This book was released on 2005 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors present a search for the standard model Higgs boson decaying into b{bar b} and produced in association with W bosons in p{bar p} collisions at √s = 1.96 TeV. This search uses 320 pb−1 of the dataset accumulated by the upgraded Collider Detector at Fermilab. Events are selected that have a high-transverse momentum electron or muon, missing transverse energy, and two jets, at least one of which is consistent with the hadronization of a b quark. Both the number of events and the dijet mass distribution are consistent with standard model background expectations, and they set 95% confidence level upper limits on the production cross section times branching ratio for the Higgs boson or any new particle with similar decay kinematics. These upper limits range from 10 pb for m{sub H} = 110 GeV/c2 to 3 pb for m{sub H} = 150 GeV/c2.
Download or read book High Energy Physics Index written by and published by . This book was released on 1990 with total page 786 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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