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Search For Standard Model Higgs Boson Produced In Association With A Top Antitop Quark Pair In 196 Tev Proton Antiproton Collisions
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Book Synopsis Search for Standard Model Higgs Boson Produced in Association with a Top-Antitop Quark Pair in 1.96 TeV Proton-Antiproton Collisions by :
Download or read book Search for Standard Model Higgs Boson Produced in Association with a Top-Antitop Quark Pair in 1.96 TeV Proton-Antiproton Collisions written by and published by . This book was released on 2007 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes the first search for Standard Model Higgs boson production in association with a top-antitop quark pair in proton-antiproton collisions at a centre of mass energy of 1.96 TeV. The integrated luminosity for othis search corresponds to 319 pb-1 of data recorded by the Collider Detector at Fermilab. We outline the even selection criteria, evaluate the even acceptance and estimate backgrounds from Standard Model sources. These events are observed that satisfy our event selection, while 2.16 ± 0.66 events are expected from background processes. no significant excess of events above background is thus observed, and we set 95% confidence level upper limits on the production cross section for this process as a function of the Higgs mass. For a Higgs boson mass of 115 GeV/c2 we find that [sigma]$t\bar{t}H$ x BR (H 2!bb)
Book Synopsis Search for Standard Model Higgs Boson Produced in Association with a Top Anti-top Quark Pair in 1.96 TeV Proton - Anti-proton Collisions by :
Download or read book Search for Standard Model Higgs Boson Produced in Association with a Top Anti-top Quark Pair in 1.96 TeV Proton - Anti-proton Collisions written by and published by . This book was released on 2006 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Search for Standard Model Higgs Boson Produced in Association with a Top-antitop Quark Pair in 1.96 TeV Proton-antiproton Collisions by : Stanley T. Lai
Download or read book Search for Standard Model Higgs Boson Produced in Association with a Top-antitop Quark Pair in 1.96 TeV Proton-antiproton Collisions written by Stanley T. Lai and published by . This book was released on 2007 with total page 103 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes the first search for Standard Model Higgs boson production in association with a top-antitop quark pair in proton-antiproton collisions at a centre of mass energy of 1.96 TeV. The integrated luminosity for this search corresponds to 319 pb-1 of data recorded by the Collider Detector at Fermilab. We outline the event selection criteria, evaluate the event acceptance and estimate backgrounds from Standard Model sources. Three events are observed that satisfy our event selection, while 2.16 +/- 0.66 events are expected from background processes. No significant excess of events above background is thus observed, and we set 95% confidence level upper limits on the production cross section for this process as a function of the Higgs mass. For a Higgs boson mass of 115 GeV/ c2, we find that sigmatt H x BR(H b b)
Book Synopsis A Search for the Standard Model Higgs Boson Produced in Association with a W Boson by : Martin J. Frank
Download or read book A Search for the Standard Model Higgs Boson Produced in Association with a W Boson written by Martin J. Frank 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 a standard model Higgs boson produced in association with a W boson using data collected with the CDF II detector from proton/antiproton collisions at a center of mass energy of 1.96 TeV. The search is performed in the WH channel where the W boson decays leptonically and the Higgs boson decays to a bottom/antibottom quark pair. The two quarks usually fragment into two jets, but sometimes a third jet can be produced via gluon radiation, so we have increased the standard two-jet sample by including events that contain three jets. We reconstruct the Higgs boson using two or three jets depending on the kinematics of the event. We find an improvement in our search sensitivity using the larger sample together with this multijet reconstruction technique. Our data show no evidence of a Higgs boson, so we set 95% confidence level upper limits on the WH production rate. We set limits between 3.36 and 28.7 times the standard model prediction for Higgs boson masses ranging from 100 to 150 GeV/c^2.
Book Synopsis Improved Search for a Higgs Boson Produced in Association with Z-]l+l- in Proton Antiproton Collisions at Sqrt(s) by :
Download or read book Improved Search for a Higgs Boson Produced in Association with Z-]l+l- in Proton Antiproton Collisions at Sqrt(s) written by and published by . This book was released on 2010 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a search for the standard model Higgs boson produced with a Z boson in 4.1 fb−1 of data collected with the CDF II detector at the Tevatron. In events consistent with the decay of the Higgs boson to a bottom-quark pair and the Z boson to electrons or muons, we set 95% credibility level upper limits on the ZH production cross section times the H --> b{bar b} branching ratio. Improved analysis methods enhance signal sensitivity by 20% relative to previous searches beyond the gain due to the larger data sample. At a Higgs boson mass of 115 GeV/c2 we set a limit of 5.9 times the standard model value.
Book Synopsis Search for the Standard Model Higgs Boson Produced in Association with Top Quarks and Decaying Into a B ̄ B Pair in P P Collisions at √ S by : Felix Bührer
Download or read book Search for the Standard Model Higgs Boson Produced in Association with Top Quarks and Decaying Into a B ̄ B Pair in P P Collisions at √ S written by Felix Bührer and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Search for the Standard Model Higgs Boson Produced in Association with Top Quarks in the Lepton Plus Jets Channel by : Sean C. Flowers
Download or read book Search for the Standard Model Higgs Boson Produced in Association with Top Quarks in the Lepton Plus Jets Channel written by Sean C. Flowers and published by . This book was released on 2017 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results for the search of a Higgs boson decaying to a bottom quark-antiquark pair produced with a top quark-antiquark pair (t ̄tH) in the lepton plus jets channel in proton-proton collisions at a center-of-mass energy of √ s = 13 TeV are presented. The data used corresponds to an integrated luminosity of 12.9 fb−1 recorded with the CMS experiment in 2016. To increase the sensitivity of the search, selected events are categorized by number of jets and number of b-tagged jets resulting in different expected signal and background rates. For each category two multivariate techniques are combined to separate the signal and background events. A machine learning process called a boosted decision tree (BDT) is trained on the two types of classes of events and then split into high and low purity based on the output. The physics motivated matrix element method (MEM) is applied to the BDT output to obtain the final two dimensional discriminator. The result is presented in terms of the t ̄tH signal strength modifier μ, the ratio of the observed t ̄tH production cross section relative to the expected cross section based on a 125 GeV Standard Model Higgs boson. A combined fit of the final discriminant in all categories of the lepton plus jets channel results an observed (expected) upper limit of μ
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 206 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$ar{p}$ collisions at √s = 1.96 TeV, collected with the DØ 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$ar{p}$ → ZH → v$ar{v}$b$ar{b}$ production. The search is also sensitive to the WH → lvb$ar{b}$ 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$ar{p}$ → (Z/W)H) x (H → b$ar{b}$). 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 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 Measurement of Top Quark Properties and Search for the Standard Model Higgs Boson in Proton Anti-Proton Collisions at $\sqrt{s}$ by :
Download or read book Measurement of Top Quark Properties and Search for the Standard Model Higgs Boson in Proton Anti-Proton Collisions at $\sqrt{s}$ 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 measurement of the top quark mass and of the top-antitop (tf) pair production cross section and a search for the Standard Model Higgs boson with CDF II Detector in pp collisions at $\sqrt{s}$ = 1.96 TeV. The integrated luminosity of 2.9 $fb^{-1}$ is used for top-antitop pair production cross section and top quark mass measurement. We adopt a neural-network algorithm to select candidate events from six or more jets. At least one of these jets should be required to be b jet, as identified by the reconstruction of a secondary vertex inside the jet. The mass measurement is based on a likelihood fit incorporating reconstructed mass distributions representative of signal and background, where the absolute jet energy scale (JES) is measured simultaneously with the top quark mass. The measurement yields a value of 174.8 ± 2.4 (stat + JES) $^{+1.2}_{-1.0}$ (syst) GeV/$c^2$, where the uncertainty from the absolute jet energy scale is evaluated together with the statistical uncertainty. The procedure also measures the amount of signal from which we derive a cross section, $\sigma_{t\bar{t}}$ = 7.2 ± 0.5 (stat) ±1.0 (syst) ± 0.4 (lum) $pb$, for the measured values of top quark mass and JES. Top quark mass and W boson mass constrain the mass of the Standard Model Higgs boson, indirectly. This prediction implies MH = 89 $^{+35}_{-26}$GeV/$c^2$ (68% confidence level) as of July 2010. Therefore, we concentrate on the Standard Model Higgs mass search region with $\le$ 135 GeV / $c^2$ . Then, we search for the Standard Model Higgs boson associated with vector boson using the decay modes consisting of leptons only: Signal processes are $WH \to \ell \nu + \tau\tau$ and $ZH \to l l + \tau \tau$. We simply select 3 or 4 lepton including hadronic T to pick candidate events out. To improve search sensitivity, we adopt Support Vector Machine to discriminate signals from backgrounds. Using about 6.2 $fb^{-1}$ data, there was no clear discrepancy between data and our background estimation. Therefore, we extract cross section upper limit of the Standard Model Higgs production at 95 % confidence level. The observed upper limit on assumption of $M_H$ = 115 GeV/$c^2$ is 25.1 x $\sigma^{SM}$ at 95% confidence level while the expectation is 17.3 x $\sigma ^{SM}$ at 95%.
Book Synopsis The Standard Model Higgs Boson Produced in Association with a T-quark Pair and Decaying to a B-quark Pair from LHC Run-2 Proton-proton 13 TeV Collisions in ATLAS. by : William Dmitri Morgan Breaden Madden
Download or read book The Standard Model Higgs Boson Produced in Association with a T-quark Pair and Decaying to a B-quark Pair from LHC Run-2 Proton-proton 13 TeV Collisions in ATLAS. written by William Dmitri Morgan Breaden Madden and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Search for the Standard Model Higgs Boson Produced in Association with a Vector Boson and Decaying Into a Tau Pair in Pp Collisions at S by :
Download or read book Search for the Standard Model Higgs Boson Produced in Association with a Vector Boson and Decaying Into a Tau Pair in Pp Collisions at S written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for the standard model Higgs boson produced in association with a vector boson with the decay H → ?? is presented. The data correspond to 20.3 fb-1 of integrated luminosity from proton-proton collisions at √s=8 TeV recorded by the ATLAS experiment at the LHC during 2012. The data agree with the background expectation, and 95% confidence-level upper limits are placed on the cross section of this process. The observed (expected) limit, expressed in terms of the signal strength ? = ?/?SM for mH = 125 GeV, is ?
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 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:
Book Synopsis Search for the Higgs Boson Produced in Association with a Vector Boson Using Like-Sign Dilepton Events in 1.96-TeV Proton-Antiproton Collisions by :
Download or read book Search for the Higgs Boson Produced in Association with a Vector Boson Using Like-Sign Dilepton Events in 1.96-TeV Proton-Antiproton Collisions 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 presents a search for the standard model and fermiophobic Higgs bosons produced in association with a vector boson using like-sign dilepton events collected by Collider Detector at Fermilab (CDF II). This analysis uses the data corresponding to an integrated luminosity of 9.4 fb -1. The search is characterized by minimally biased cuts which maximize the acceptance of the Higgs bosons. The numbers of expected signal events passing requirements for like-sign dilepton are 5.6 for the fermiophobic Higgs on the mass of 110 GeV/c2 assuming the standard model production cross section, and 1.7 for the standard model on the mass of 160 GeV/c2. The expectation of background events are 696.1, while the number of observed events are 624. To discriminate signal events from backgrounds, the search employs a multivariate analysis based on boosted decision trees. There are no significant disagreements in the BDT outputs, then, upper limits at a 95% confidence level are set on [sigma](p$\bar{p}$2! h) × B(h2!W) for both Higgs bosons scenarios. The expected and observed limits are 5.9 and 9.2, respectively, relative to the standard model expectation for the standard model Higgs boson mass of 160 GeV/c2. For the fermiophobic Higgs boson corresponding to the mass of 110 GeV/c2, the expected and observed limits are 2.6 and 4.4, respectively.
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 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.
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