Anomalous Higgs Boson Couplings in Vector Boson Fusion : by Tinghua Chen
Anomalous Higgs Boson Couplings in Vector Boson Fusion : by Tinghua Chen

Author: Tinghua Chen

Publisher:

Published: 2023

Total Pages: 0

ISBN-13:

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The discovery of the Higgs boson at the Large Hadron Collider (LHC) in 2012 marked a significant milestone in particle physics. Since then, extensive investigations have been carried out to unravel the properties of the Higgs boson and understand its interactions with other fundamental particles. Monte Carlo simulations play an important role in studies of particle physics. They generate theoretical predictions and can be compared with experimental data to test our understanding of physics. In this dissertation, the anomalous Higgs boson coupling to vector bosons was implemented in VBFNLO for Higgs boson plus three jets via VBF at the next-to-leading order (NLO) accuracy. I present results for a number of collider observables that are sensitive to the CP structure, whether in different CP scenarios and in the Standard Model. I also investigate the effects of NLO multijet merging and NLO QCD corrections matched to a parton shower on selected observables through the framework provided by Herwig 7.

Search for the Higgs Boson in the Vector Boson Fusion Channel at the ATLAS Detector
Search for the Higgs Boson in the Vector Boson Fusion Channel at the ATLAS Detector

Author: Eric Ouellette

Publisher: Springer

Published: 2015-01-20

Total Pages: 114

ISBN-13: 3319135996

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This Thesis describes the first measurement of, and constraints on, Higgs boson production in the vector boson fusion mode, where the Higgs decays to b quarks (the most common decay channel), at the LHC. The vector boson fusion mode, in which the Higgs is produced simultaneously with a pair of quark jets, provides an unparalleled opportunity to study the detailed properties of the Higgs, including the possibility of parity and CP violation, as well as its couplings and mass. It thus opens up this new field of study for precision investigation as the LHC increases in energy and intensity, leading the way to this new and exciting arena of precision Higgs research.

Higgs Constraints from Vector Boson Fusion and Scattering
Higgs Constraints from Vector Boson Fusion and Scattering

Author:

Publisher:

Published: 2015

Total Pages: 17

ISBN-13:

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We present results on 4-lepton + 2-jet production, the partonic processes most commonly described as vector boson pair production in the Vector Boson Fusion (VBF) mode. This final state contains diagrams that are mediated by Higgs boson exchange. We focus particularly on the high-mass behaviour of the Higgs boson mediated diagrams, which unlike on-shell production, gives information about the Higgs couplings without assumptions on the Higgs boson total width. We assess the sensitivity of the high-mass region to Higgs coupling strengths, considering all vector boson pair channels, W−W, W"W", W"Z and ZZ. Because of the small background, the most promising mode is WW which has sensitivity to Higgs couplings because of Higgs boson exchange in the t-channel. Using the Caola-Melnikov (CM) method, the off-shell couplings can be interpreted as bounds on the Higgs boson total width. We estimate the bound that can be obtained with current data, as well as the bounds that could be obtained at [arrow]" = 13TeV in the VBF channel for data samples of 100 and 300 fb−1. The CM method has already been successfully applied in the gluon fusion (GGF) production channel. The VBF production channel gives important complementary information, because both production and decay of the Higgs boson occur already at tree graph level.

Study of (W/Z)H Production and Higgs Boson Couplings Using H2!W W * Decays with the ATLAS Detector
Study of (W/Z)H Production and Higgs Boson Couplings Using H2!W W * Decays with the ATLAS Detector

Author:

Publisher:

Published: 2015

Total Pages:

ISBN-13:

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A search for Higgs boson production in association with a W or Z boson, in the H2!W W * decay channel, is performed with a data sample collected with the ATLAS detector at the LHC in proton-proton collisions at centre-of-mass energies \(\sqrt{s}=7 \) TeV and 8 TeV, corresponding to integrated luminosities of 4.5 fb-1 and 20.3 fb-1, respectively. The WH production mode is studied in two-lepton and three-lepton final states, while two- lepton and four-lepton final states are used to search for the ZH production mode. The observed significance, for the combined W H and ZH production, is 2.5 standard deviations while a significance of 0.9 standard deviations is expected in the Standard Model Higgs boson hypothesis. The ratio of the combined W H and ZH signal yield to the Standard Model expectation, [mu]V H, is found to be [mu] V H = 3.0-1.1+1.3 (stat.)-0.7 +1.0 (sys.) for the Higgs boson mass of 125.36 GeV. The W H and ZH production modes are also combined with the gluon fusion and vector boson fusion production modes studied in the H 2!W W * 2!l[nu]l[nu] decay channel, resulting in an overall observed significance of 6.5 standard deviations and [mu]ggF + VBF + VH = 1.16-0.15+0.16 (stat.) -0.15+0.18 (sys.). The results are interpreted in terms of scaling factors of the Higgs boson couplings to vector bosons ([kappa]V) and fermions ([kappa]F); the combined results are.

Study of (W/Z)H Production and Higgs Boson Couplings Using H2!WW* Decays with the ATLAS Detector
Study of (W/Z)H Production and Higgs Boson Couplings Using H2!WW* Decays with the ATLAS Detector

Author:

Publisher:

Published: 2015

Total Pages: 65

ISBN-13:

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A search for Higgs boson production in association with a W or Z boson, in the H2!W W* decay channel, is performed with a data sample collected with the ATLAS detector at the LHC in proton-proton collisions at centre-of-mass energies [arrow]"=7 TeV and 8 TeV, corresponding to integrated luminosities of 4.5 fb-1 and 20.3 fb-1, respectively. The WH production mode is studied in two-lepton and three-lepton final states, while two- lepton and four-lepton final states are used to search for the ZH production mode. The observed significance, for the combined WH and ZH production, is 2.5 standard deviations while a significance of 0.9 standard deviations is expected in the Standard Model Higgs boson hypothesis. The ratio of the combined WH and ZH signal yield to the Standard Model expectation, [mu]VH, is found to be [mu]VH = 3.0-1.1+1.3 (stat.)-0.7+1.0 (sys.) for the Higgs boson mass of 125.36 GeV. WH and ZH production modes are also combined with the gluon fusion and vector boson fusion production modes studied in the H 2!W W* 2!l[nu]l[nu] decay channel, resulting in an overall observed significance of 6.5 standard deviations and [mu]ggF+VBF+VH=1.16-0.15+0.16 (stat.) -0.15+0.18 (sys.). The results are interpreted in terms of scaling factors of the Higgs boson couplings to vector bosons ([kappa]V) and fermions ([kappa]F); the combined results are.

Measurements of Higgs Boson Production and Couplings in Diboson Final States with the ATLAS Detector at the LHC.
Measurements of Higgs Boson Production and Couplings in Diboson Final States with the ATLAS Detector at the LHC.

Author:

Publisher:

Published: 2013

Total Pages:

ISBN-13:

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Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H→[gamma][gamma], H→ZZ{sup *}→4l and H→WW{sup *}→l[nu]l[nu]. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of {radical s}=7 TeV and {radical s}=8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson.

Constraints on New Phenomena Via Higgs Boson Couplings and Invisible Decays with the ATLAS Detector
Constraints on New Phenomena Via Higgs Boson Couplings and Invisible Decays with the ATLAS Detector

Author:

Publisher:

Published: 2015

Total Pages: 52

ISBN-13:

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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.