Search For Higgs Boson Decays In The H2 W W 2 Vlv Channel Via Vector Boson Fusion With The Atlas Detector At The Lhc
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Search For Higgs Boson Decays In The H2 W W 2 Vlv Channel Via Vector Boson Fusion With The Atlas Detector At The Lhc
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Author : Bonnie Kar Bo Chow
language : en
Publisher:
Release Date : 2014
Search For Higgs Boson Decays In The H2 W W 2 Vlv Channel Via Vector Boson Fusion With The Atlas Detector At The Lhc written by Bonnie Kar Bo Chow and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
Evidence For The Production Of The Standard Model Higgs Boson Produced Via Vector Boson Fusion In The Ww Channel At The Atlas Detector
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Author : Koos van Nieuwkoop
language : en
Publisher:
Release Date : 2017
Evidence For The Production Of The Standard Model Higgs Boson Produced Via Vector Boson Fusion In The Ww Channel At The Atlas Detector written by Koos van Nieuwkoop and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
In 2012, the ATLAS and CMS experiments at CERN's Large Hadron Collider announced they had each observed a new particle with a mass of about 125 GeV/c^2. Given the available data, the properties of this particle are consistent with the Higgs boson predicted by the Standard Model of particle physics (SM). The Higgs boson, as proposed within the SM, is the simplest manifestation of the Brout-Englert-Higgs mechanism. This discovery was driven by the gluon fusion (ggF) production mode, the dominant Higgs boson production mechanism at the LHC. The SM also predicts that the Higgs boson can be produced by the fusion of two weak vector bosons (VBF). Measuring VBF Higgs boson production is an important test of the SM but it is challenging to measure given its cross section is an order of magnitude smaller than that of ggF. After H->bb, H->WW* is the dominant decay channel for the SM Higgs boson at 125 GeV/c^2 and is therefore a promising channel to measure its properties. In addition, the VBF H->WW* search channel makes it possible to probe the exclusive coupling of the Higgs boson to the weak vector bosons. Precise measurements of these coupling strengths make it possible to constrain new models of physics beyond the SM. Despite its relatively large branching ratio, H->WW*->lnln is a challenging channel to search for the Higgs boson because of the neutrinos in the final state which are not directly detectable by the ATLAS detector. Consequently, it is not possible to fully reconstruct the mass of the WW system. Furthermore, there are several backgrounds that have the same signature in the detector as the signal. Top quark pair production is the largest background in this analysis. A multivariate analysis technique, based on an eight-variable boosted decision tree (BDT), is used to search for VBF H->WW*->lnln in the Run-I data and a subset of the Run-II data. This analysis provides the first evidence for VBF H->WW*->lnln with a significance of 3.2 standard deviations in Run-I and 1.9 standard deviations in Run-II. The measured signal strength relative to the rate predicted by the SM for VBF H->WW*->lnln is 1.3 +/- 0.5 using the Run-I data, and 1.7 +1.1/-0.9 using a fraction of the Run-II data.
Search For Invisible Higgs Boson Decays In Events With Vector Boson Fusion Signatures Using 139 Fb 1 Of Proton Proton Data Recorded By The Atlas Experiment
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Author : [Study Group] ATLAS Collaboration CERN
language : en
Publisher:
Release Date : 2022
Search For Invisible Higgs Boson Decays In Events With Vector Boson Fusion Signatures Using 139 Fb 1 Of Proton Proton Data Recorded By The Atlas Experiment written by [Study Group] ATLAS Collaboration CERN and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022 with categories.
Abstract: A direct search for Higgs bosons produced via vector-boson fusion and subsequently decaying into invisible particles is reported. The analysis uses 139 fb−1 of pp collision data at a centre-of-mass energy of s√ = 13 TeV recorded by the ATLAS detector at the LHC. The observed numbers of events are found to be in agreement with the background expectation from Standard Model processes. For a scalar Higgs boson with a mass of 125 GeV and a Standard Model production cross section, an observed upper limit of 0.145 is placed on the branching fraction of its decay into invisible particles at 95% confidence level, with an expected limit of 0.103. These results are interpreted in the context of models where the Higgs boson acts as a portal to dark matter, and limits are set on the scattering cross section of weakly interacting massive particles and nucleons. Invisible decays of additional scalar bosons with masses from 50 GeV to 2 TeV are also studied, and the derived upper limits on the cross section times branching fraction decrease with increasing mass from 1.0 pb for a scalar boson mass of 50 GeV to 0.1 pb at a mass of 2 TeV
A Search For Nothing
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Author : William Balunas
language : en
Publisher:
Release Date : 2018
A Search For Nothing written by William Balunas and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with categories.
This thesis presents a search for invisible decays of the Higgs boson using the vector boson fusion channel. This uses 36 fb-1 of proton-proton collision data at [square root] s = 13 TeV using the ATLAS detector at the Large Hadron Collider. The experimental methods for understanding the signal and background processes as well as detector effects are described in detail. The search is carried out in several regions defined by kinematic requirements on the final-state objects, and the observed event yields are used in a profile-likelihood fit in order to constrain the backgrounds. The results are interpreted using a modified frequentist method and are found to be consistent with the Standard Model expectations. An upper limit of 34% (28% expected) at 95% C.L. is placed on the invisible branching ratio of the Higgs boson. Re-interpretation of these results in terms of dark matter is also discussed, in the context of the Higgs portal and other simplified models.
Search For Invisible Decays Of The Higgs Boson Produced Via Vector Boson Fusion At The Atlas Detector With 139 Fb 1 Of Integrated Luminosity
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Author : Pablo Andres Rivadeneira Bracho
language : en
Publisher:
Release Date : 2022
Search For Invisible Decays Of The Higgs Boson Produced Via Vector Boson Fusion At The Atlas Detector With 139 Fb 1 Of Integrated Luminosity written by Pablo Andres Rivadeneira Bracho and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022 with categories.
Search For A Charged Higgs Boson Produced In The Vector Boson Fusion Mode With Decay H U2192 W Z Using Pp Collisions At U221a S
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Author :
language : en
Publisher:
Release Date : 2015
Search For A Charged Higgs Boson Produced In The Vector Boson Fusion Mode With Decay H U2192 W Z Using Pp Collisions At U221a 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 2015 with categories.
A search for a charged Higgs boson, H±, decaying to a W± boson and a Z boson is presented. The search is based on 20.3 fb–1 of proton-proton collision data at a center-of-mass energy of 8 TeV recorded with the ATLAS detector at the LHC. The H± boson is assumed to be produced via vector-boson fusion and the decays W± → qq¯' and Z → e+e–/?+?– are considered. The search is performed in a range of charged Higgs boson masses from 200 to 1000 GeV. No evidence for the production of an H± boson is observed. Upper limits of 31–1020 fb at 95% C.L. are placed on the cross section for vector-boson fusion production of an H± boson times its branching fraction to W±Z. The limits are compared with predictions from the Georgi-Machacek Higgs triplet model.
Search For Invisible Decays Of Higgs Bosons In The Vector Boson Fusion And Associated Zh Production Modes
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Author :
language : en
Publisher:
Release Date : 2014
Search For Invisible Decays Of Higgs Bosons In The Vector Boson Fusion And Associated Zh Production Modes written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
A search for invisible decays of Higgs bosons is performed using the vector boson fusion and associated ZH production modes. In the ZH mode, the Z boson is required to decay to a pair of charged leptons or a b b-bar quark pair. The searches use the 8 TeV pp collision dataset collected by the CMS detector at the LHC, corresponding to an integrated luminosity of up to 19.7 inverse femtobarns. Certain channels include data from 7 TeV collisions corresponding to an integrated luminosity of 4.9 inverse femtobarns. The searches are sensitive to non-standard-model invisible decays of the recently observed Higgs boson, as well as additional Higgs bosons with similar production modes and large invisible branching fractions. In all channels, the observed data are consistent with the expected standard model backgrounds. Limits are set on the production cross section times invisible branching fraction, as a function of the Higgs boson mass, for the vector boson fusion and ZH production modes. By combining all channels, and assuming standard model Higgs boson cross sections and acceptances, the observed (expected) upper limit on the invisible branching fraction at m[H] = 125 GeV is found to be 0.58 (0.44) at 95% confidence level. We interpret this limit in terms of a Higgs-portal model of dark matter interactions.
Observation And Measurement Of Higgs Boson Decays To Ww With The Atlas Detector
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Author :
language : en
Publisher:
Release Date : 2015
Observation And Measurement Of Higgs Boson Decays To Ww With The Atlas Detector written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
We report the observation of Higgs boson decays to WW* based on an excess over background of 6.1 standard deviations in the dilepton final state, where the Standard Model expectation is 5.8 standard deviations. Evidence for the vector-boson fusion (VBF) production process is obtained with a significance of 3.2 standard deviations. The results are obtained from a data sample corresponding to an integrated luminosity of 25 fb-1 from [arrow]"=7 and 8 TeV pp collisions recorded by the ATLAS detector at the LHC. For a Higgs boson mass of 125.36 GeV, the ratio of the measured value to the expected value of the total production cross section times branching fraction is 1.09+0.16-0.15(stat)+0.17-0.14(syst). The corresponding ratios for the gluon fusion and vector-boson fusion production mechanisms are 1.02 " 0.19(stat)+0.22-0.18(syst) and 1.27+0.44-0.40(stat)+0.30-0.21(syst), respectively. At [arrow]"=8 TeV, the total production cross sections are measured to be [sigma](gg 2!>H 2!WW*)=4.6"0.9(stat)+0.8-0.7(syst) pb and [sigma](VBF H 2!W*)=0.51+0.17-0.15(stat)+0.13-0.08(syst) pb. The fiducial cross section is determined for the gluon-fusion process in exclusive final states with 0 or one associated jet.
Constraints On New Phenomena Via Higgs Boson Couplings And Invisible Decays With The Atlas Detector
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Author :
language : en
Publisher:
Release Date : 2015
Constraints On New Phenomena Via Higgs Boson Couplings And Invisible Decays With The Atlas Detector written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
The ATLAS experiment at the LHC has measured the Higgs boson couplings and mass, and searched for invisible Higgs boson decays, using multiple production and decay channels with up to 4.7 fb-1 of pp collision data at √s=7 TeV and 20.3 fb-1 at √s=8 TeV. In the current study, the measured production and decay rates of the observed Higgs boson in the [gamma][gamma], ZZ, W W , Z[gamma], bb, [tau] [tau] , and [mu][mu] decay channels, along with results from the associated production of a Higgs boson with a top-quark pair, are used to probe the scaling of the couplings with mass. The limits are set on parameters in extensions of the Standard Model including a composite Higgs boson, an additional electroweak singlet, and two-Higgs-doublet models. Together with the measured mass of the scalar Higgs boson in the [gamma][gamma] and ZZ decay modes, a lower limit is set on the pseudoscalar Higgs boson mass of mA > 370 GeV in the "hMSSM" simplified Minimal Supersymmetric Standard Model. Results from direct searches for heavy Higgs bosons are also interpreted in the hMSSM. Finally, direct searches for invisible Higgs boson decays in the vector-boson fusion and associated production of a Higgs boson with W/Z (Z → ll, W/Z → jj) modes are statistically combined to set an upper limit on the Higgs boson invisible branching ratio of 0.25. As a result, the use of the measured visible decay rates in a more general coupling fit improves the upper limit to 0.23, constraining a Higgs portal model of dark matter.
Search For The Higgs Boson Produced Via Vector Boson Fusion In The Decay Channel H To Tau Tau
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Author : Joram Berger
language : en
Publisher:
Release Date : 2014
Search For The Higgs Boson Produced Via Vector Boson Fusion In The Decay Channel H To Tau Tau written by Joram Berger and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.