Download or read book Combination of Searches for the Higgs Boson Using the Full CDF Data Set written by and published by . This book was released on 2013 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for the Higgs Boson in the All hadronic Final State Using the Full CDF Data Set written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Combination of Standard Model Higgs Searches at CDF written by and published by . This book was released on 2010 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present the latest combination of searches for a standard model (SM) Higgs boson in p{bar p} collisions at (square root)s = 1.96 TeV recorded by the CDF II detector at the Fermilab Tevatron. Using data corresponding to 2.3-5.9 fb−1 of integrated luminosity, we perform searches in a number of different production and decay modes and then combine them to improve sensitivity. No excess in data above that expected from backgrounds is observed; therefore, we set upper limits on the production cross section times branching fraction as a function of the SM Higgs boson mass (m{sub H}). The combined observed (expected) limit is 1.9 (1.8) times the SM prediction at m{sub H} =115 GeV/c2 and 1.0 (1.1) times the SM prediction at m{sub H} = 165 GeV/c2.
Download or read book Discovery Of The Higgs Boson written by Aleandro Nisati and published by World Scientific. This book was released on 2016-08-26 with total page 470 pages. Available in PDF, EPUB and Kindle. Book excerpt: The recent observation of the Higgs boson has been hailed as the scientific discovery of the century and led to the 2013 Nobel Prize in physics. This book describes the detailed science behind the decades-long search for this elusive particle at the Large Electron Positron Collider at CERN and at the Tevatron at Fermilab and its subsequent discovery and characterization at the Large Hadron Collider at CERN. Written by physicists who played leading roles in this epic search and discovery, this book is an authoritative and pedagogical exposition of the portrait of the Higgs boson that has emerged from a large number of experimental measurements. As the first of its kind, this book should be of interest to graduate students and researchers in particle physics.
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.
Download or read book A Search for the Standard Model Higgs Boson in CDF II Data written by and published by . This book was released on 2012 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents a search for the standard model Higgs boson in the associated production process p $\bar{p}$ → ZH → e+e-b$\bar{b}$. Data amounting to an integrated luminosity of 7.5 fb-1 at √s = 1.96 TeV collected at the Collider Detector at Fermilab (CDF) at the Tevatron are analyzed. Two objectives are pursued in the methods applied: maximize acceptance, and distinguish the signal from background. The first aim is met by applying a neural-network-based electron identi cation and considering multiple electron triggers in an effort to improve Z acceptance. In an attempt to maximize the Higgs acceptance, three b quark identification schemes are used allowing for varying event conditions. The latter goal is met by employing more multivariate techniques. First, the dijet mass resolution is improved by a neural network. Then, both single variables and boosted decision tree outputs are fed into a segmented final discriminant simultaneously isolating the signal-like events from the Z with additional jets background and the kinematically di erent tt background. Good agreement is seen with the null hypothesis and upper production cross section ( ZH) times branching ratio (BR(H →b $\bar{b}$)) limits are set for 11 mass hypotheses between 100 and 150 GeV/c2 at the 95% confidence level. For a Higgs boson mass of 115 GeV/c2, this channel sets an observed (expected) upper limit of 3.9 (5.8) times the standard model value of ZH BR(H → b $\bar{b}$). The inclusion of this channel within the combined CDF and Tevatron limits is discussed.
Download or read book Combined CDF and D0 Upper Limits on Standard Model Higgs Boson Production with Up to 8 6 Fb 1 of Data written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We combine results from CDF and D0 on direct searches for the standard model (SM) Higgs boson (H) in p{bar p} collisions at the Fermilab Tevatron at √s = 1.96 TeV. Compared to the previous Tevatron Higgs boson search combination more data have been added, additional channels have been incorporated, and some previously used channels have been reanalyzed to gain sensitivity. We use the MSTW08 parton distribution functions and the latest theoretical cross sections when comparing our limits to the SM predictions. With up to 8.2 fb−1 of data analyzed at CDF and up to 8.6 fb−1 at D0, the 95% C.L. our upper limits on Higgs boson production are factors of 1.17, 1.71, and 0.48 times the values of the SM cross section for Higgs bosons of mass m{sub H} = 115 GeV/c2, 140 GeV/c2, and 165 GeV/c2, respectively. The corresponding median upper limits expected in the absence of Higgs boson production are 1.16, 1.16, and 0.57. There is a small (≈ 1[sigma]) excess of data events with respect to the background estimation in searches for the Higgs boson in the mass range 125
Download or read book Higgs Boson Searches at CDF written by and published by . This book was released on 2009 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results are presented on searches for standard model and non-standard model production of a Higgs boson in pbar-p collisions at (square root)s = 1.96 TeV with the CDF II detector at the Fermilab Tevatron. Using data corresponding to 2-3.6 1/fb of integrated luminosity, searches are performed in a number of different production and decay modes. No excess in data above that expected from backgrounds is observed; therefore, we set upper limits on the production cross section times branching fraction as a function of the Higgs boson mass.
Download or read book Search for the Standard Model Higgs Boson Associated with a W Boson Using Matrix Element Technique in the CDF Detector at the Tevatron written by and published by . This book was released on 2010 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis a direct search for the Standard Model Higgs boson production in association with a W boson at the CDF detector in the Tevatron is presented. This search contributes predominantly in the region of low mass Higgs region, when the mass of Higgs boson is less than about 135 GeV. The search is performed in a final state where the Higgs boson decays into two b quarks, and the W boson decays leptonically, to a charged lepton (it can be an electron or a muon) and a neutrino. This work is organized as follows. Chapter 2 gives an overview of the Standard Model theory of particle physics and presents the SM Higgs boson search results at LEP, and the Tevatron colliders, as well as the prospects for the SM Higgs boson searches at the LHC. The dataset used in this analysis corresponds to 4.8 fb−1 of integrated luminosity of p{bar p} collisions at a center of mass energy of 1.96 TeV. That is the luminosity acquired between the beginning of the CDF Run II experiment, February 2002, and May 2009. The relevant aspects, for this analysis, of the Tevatron accelerator and the CDF detector are shown in Chapter 3. In Chapter 4 the particles and observables that make up the WH final state, electrons, muons, E{sub T}, and jets are presented. The CDF standard b-tagging algorithms to identify b jets, and the neural network flavor separator to distinguish them from other flavor jets are also described in Chapter 4. The main background contributions are those coming from heavy flavor production processes, such as those coming from Wbb, Wcc or Wc and tt. The signal and background signatures are discussed in Chapter 5 together with the Monte CArlo generators that have been used to simulate almost all the events used in this thesis. WH candidate events have a high-p{sub T} lepton (electron or muon), high missing transverse energy, and two or more than two jets in the final state. Chapter 6 describes the event selection applied in this analysis and the method used to estimate the background contribution. The Matrix Element method, that was successfully used in the single t0p discovery analysis and many other analyses within the CDF collaboration, is the multivariate technique used in this thesis to discriminate signal from background events. With this technique is possible to calculate a probability for an event to be classified as signal or background. These probabilities are then combined into a discriminant function called the Event Probability Discriminant, EPD, which increases the sensitivity of the WH process. This method is described in detail in Chapter 7. As no evidence for the signal has been found, the results obtained with this work are presented in Chapter 8 in terms of exclusion regions as a function of the mass of the Higgs boso, taking into account the full systematics. The conclusions of this work to obtain the PhD are presnted in Chapter 9.
Download or read book Combined Upper Limit on Standard Model Higgs Boson Production at CDF written by and published by . This book was released on 2012 with total page 4 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 neither been confirmed nor refuted. The CDF collaboration has performed SM Higgs searches in many channels using p{bar p} collisions at a centre-of-mass energy √s = 1.96 TeV. We present the latest combined Higgs boson search at CDF. Since the previous year's combination, the sensitivity is increased through the addition of new channels, the improvement of existing channels and the addition of new data samples. We also use the latest parton distribution functions and gg → H theoretical cross sections when modelling the signal event yields. Using integrated luminosities of up to 8.2 fb−1, we observe a good agreement between data and the background prediction. Since we do not see a Higgs boson excess, we set 95% CL upper limits on the Higgs boson cross section in the range between 100 and 200 GeV/c2, with 5 GeV/c2 increments. The observed (expected) limits for a 115 and a 165 GeV/c2 Higgs boson are 1.55 (1.49) and 0.75 (0.79) x SM, respectively. Since last year, the Higgs boson excluded range by CDF is extended to 156.5 - 173.7 and 100 - 104.5 GeV/c2.
Download or read book Updated Search for the Standard Model Higgs Boson in Events with Jets and Missing Transverse Energy Using the Full CDF Data Set written by 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 Constraints on Models of the Higgs Boson with Exotic Spin and Parity Using Decays to Bottom Antibottom Quarks in the Full CDF Data Set written by and published by . This book was released on 2015 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, a search for particles with the same mass and couplings as those of the standard model Higgs boson but different spin and parity quantum numbers is presented. We test two specific alternative Higgs boson hypotheses: a pseudoscalar Higgs boson with spin-parity JP = 0- and a gravitonlike Higgs boson with JP = 2+, assuming for both a mass of 125 GeV/c2. We search for these exotic states produced in association with a vector boson and decaying into a bottom-antibottom quark pair. The vector boson is reconstructed through its decay into an electron or muon pair, or an electron or muon and a neutrino, or it is inferred from an imbalance in total transverse momentum. We use expected kinematic differences between events containing exotic Higgs bosons and those containing standard model Higgs bosons. The data were collected by the CDF experiment at the Tevatron proton-antiproton collider, operating at a center-of-mass energy of √s = 1.96 TeV, and correspond to an integrated luminosity of 9.45 fb-1. We exclude deviations from the predictions of the standard model with a Higgs boson of mass 125 GeV/c2 at the level of 5 standard deviations, assuming signal strengths for exotic boson production equal to the prediction for the standard model Higgs boson, and set upper limits of approximately 30% relative to the standard model rate on the possible rate of production of each exotic state.
Download or read book Combined CDF and D0 Upper Limits on Standard Model Higgs Boson Production with Up to 6 7 Fb 1 of Data written by and published by . This book was released on 2010 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: We combine results from CDF and D0 on direct searches for the standard model (SM) Higgs boson (H) in p{bar p} collisions at the Fermilab Tevatron at (square root)s = 1.96 TeV. Compared to the previous Tevatron Higgs search combination more data have been added, additional new channels have been incorporated, and some previously used channels have been reanalyzed to gain sensitivity. We use the latest parton distribution functions and gg --> H theoretical cross sections when comparing our limits to the SM predictions. With up to 5.9 fb−1 of data analyzed at CDF, and up to 6.7 fb−1 at D0, the 95% C.L. upper limits on Higgs boson production are factors of 1.56 and 0.68 the values of the SM cross section for a Higgs boson mass of m{sub H} = 115 GeV/c2 and 165 GeV/c2. We exclude, at the 95% C.L., a new and larger region at high mass between 158
Download or read book Search for Standard Model Higgs Boson Production in Association with a W Boson Using a Matrix Element Technique at CDF in p bar p 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: This paper presents a search for standard model Higgs boson production in association with a W boson using events recorded by the CDF experiment in a dataset corresponding to an integrated luminosity of 5.6 fb−1. The search is performed using a matrix element technique in which the signal and background hypotheses are used to create a powerful discriminator. The discriminant output distributions for signal and background are fit to the observed events using a binned likelihood approach to search for the Higgs boson signal. We find no evidence for a Higgs boson, and 95% confidence level (C.L.) upper limits are set on?(p{bar p} → WH) x?(H → b{bar b}). The observed limits range from 3.5 to 37.6 relative to the standard model expectation for Higgs boson masses between m{sub H} = 100 GeV/c2 and m{sub H} = 150 GeV/c2. The 95% C.L. expected limit is estimated from the median of an ensemble of simulated experiments and varies between 2.9 and 32.7 relative to the production rate predicted by the standard model over the Higgs boson mass range studied.
Download or read book Combined CDF and D0 Upper Limits on Standard Model Higgs Boson Production with Up to 8 2 Fb 1 of Data written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We combine results from CDF and D0's direct searches for the standard model (SM) Higgs boson (H) produced in p{bar p} collisions at the Fermilab Tevatron at √s = 1.96 TeV. The results presented here include those channels which are most sensitive to Higgs bosons with mass between 130 and 200 GeV/c2, namely searches targeted at Higgs boson decays to W+W−, although acceptance for decays into [tau]{sup.
Download or read book Search for the Higgs Boson in the ZH to Uubb Channel at CDF Using Novel Multivariate Techniques written by Justin Robert Pilot and published by . This book was released on 2011 with total page 131 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: We present a search for the Standard Model Higgs Boson using the process ZH to uubb. We use a dataset corresponding to 9.2/fb of integrated luminosity from proton-antiproton collisions with center-of-mass energy 1.96 TeV at the Fermilab Tevatron, collected with the CDF II detector. This analysis benefits from several new multivariate techniques that have not been used in previous analyses at CDF. We use a multivariate function to select muon candidates, increasing signal acceptance while simultaneously keeping fake rates small. We employ an inclusive trigger selection to further increase acceptance. To enhance signal discrimination, we utilize a multi-layer approach consisting of expert discriminants. This multi-layer discriminant method helps isolate the two main classes of background events, t-tbar and Z+jets production. It also includes a flavor separator, to distinguish light flavor jets from jets consistent with the decay of a B-hadron. With this novel multi-layer approach, we proceed to set limits on the ZH production cross section times branching ratio. For a Higgs boson with mass 115 GeV/c^2, we observe (expect) a limit of 8.0 (4.9) times the Standard Model prediction.
Download or read book Search for the Higgs Boson in the ZH to mu mu B bar b Channel at CDF Using Novel Multivariate Techniques 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 using the process $ZH\to\mu^+\mu^- b\bar{b}$. We use a dataset corresponding to 9.2 fb$^{-1}$ of integrated luminosity from proton-antiproton collisions with center-of-mass energy 1.96 TeV at the Fermilab Tevatron, collected with the CDF II detector. This analysis benefits from several new multivariate techniques that have not been used in previous analyses at CDF. We use a multivariate function to select muon candidates, increasing signal acceptance while simultaneously keeping fake rates small. We employ an inclusive trigger selection to further increase acceptance. To enhance signal discrimination, we utilize a multi-layer approach consisting of expert discriminants. This multi-layer discriminant method helps isolate the two main classes of background events, $t\bar{t}$ and $Z$+jets production. It also includes a flavor separator, to distinguish light flavor jets from jets consistent with the decay of a $B$-hadron. Wit h this novel multi-layer approach, we proceed to set limits on the $ZH$ production cross section times branching ratio. For a Higgs boson with mass 115 GeV/$c^2$, we observe (expect) a limit of 8.0 (4.9) times the Standard Model prediction.
