Precision Coupling Measurements Of The Higgs Boson Using The H Zz 4l Decay Channel
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| Author | : Syed Haider Abidi |
| Publisher | : |
| Total Pages | : |
| Release | : 2020 |
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| ISBN | : |
Download Precision Coupling Measurements of the Higgs Boson Using the H->ZZ*->4l Decay Channel Book in PDF, Epub and Kindle
The coupling of the Higgs boson to other particles is probed by measuring the production cross sections at the Large Hadron Collider using the ATLAS detector. The present measurement is performed using the H->ZZ*->4l decay channel, with l= electron or muon and with datasets corresponding to various integrated luminosities. The inclusive production cross section is measured to be 1.34 +/- 0.12 pb, which is in good agreement with the predicted value of 1.33 +/- 0.08 pb. The gluon-gluon fusion, the vector boson fusion, the vector boson associated and the top associated production cross sections are measured to be 1.12 +/- 0.12 pb, 110 +/- 40 fb, 75 +61 -49 fb and 27 +26 -17 fb, respectively. The differential production cross sections are also measured using the Simplified Template cross sections framework. All measurements are in good agreement with the Standard Model predictions. These results are used to measure the Higgs boson coupling to fermions and vector bosons using the kappa-framework and to derive constraints on contributions from beyond the Standard Model physics using an effective field theory approach. No significant deviations from the Standard Model are observed.
| Author | : Katharina Maria Ecker |
| Publisher | : |
| Total Pages | : 0 |
| Release | : 2018 |
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| ISBN | : |
Download Measurement of the Higgs Boson Tensor Coupling in H → ZZ* → 4l Decays with the ATLAS Detector Book in PDF, Epub and Kindle
| Author | : Katharina Maria Ecker |
| Publisher | : |
| Total Pages | : |
| Release | : 2018 |
| Genre | : |
| ISBN | : |
Download Measurement of the Higgs Boson Tensor Coupling in H → ZZ* → 4l Decays with the ATLAS Detector Book in PDF, Epub and Kindle
| Author | : |
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| Total Pages | : |
| Release | : 2015 |
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Download Measurements of Higgs Boson Production and Couplings in the Four-lepton Channel in $pp$ Collisions at Center-of-mass Energies of 7 and 8 TeV with the ATLAS Detector Book in PDF, Epub and Kindle
| Author | : Bijan Perry Berton Haney (IV) |
| Publisher | : |
| Total Pages | : 318 |
| Release | : 2018 |
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| ISBN | : |
Download The Higgs from A[mu] to Z[mu] Book in PDF, Epub and Kindle
This thesis presents measurements of the Higgs boson inclusive and differential cross sections with 36.1 fb-1 of proton-proton collision data from the Large Hadron Collider at a center of mass energy of 13 TeV recorded with the ATLAS detector. The cross sections are measured in the fiducial phase space of the H ZZ* 4l (four lepton) decay channel as well as in the total Higgs phase space, combining data from the H ZZ* 4l and H [double gamma] (diphoton) decay channels. These two channels have high sensitivity to the Higgs signal and allow for full reconstruction of the Higgs boson kinematics. Unfolding techniques are used to correct for detector effects in the measurements, and comparisons are made to various state-of-the-art Standard Model theory predictions such as the predicted gluon-gluon fusion total cross section at N3LO and the Higgs differential transverse momentum spectrum at NNLO. These precision measurements are used to set limits on anomalous Higgs boson couplings beyond the Standard Model within the framework of pseudo-observables. In the H ZZ * 4l analysis, the inclusive fiducial Higgs boson cross section is measured to be 3.62 [plus/minus] 0.50 (stat) +0.25/-0.20 (sys) fb, in agreement with the Standard Model prediction of 2.91 [plus/minus] 0.13 fb. In the combined analysis, the inclusive total cross section is measured to be 57.0 +6.0/-5.9 (stat.) +4.0/-3.3 (syst.) pb, in agreement with the Standard Model prediction of of 55.6 [plus/minus] 2.5 pb. Measured differential cross sections are also presented for the Higgs transverse momentum, Higgs rapidity, number of associated jets, leading jet transverse momentum, and other kinematic variables.
| Author | : David Hall |
| Publisher | : Springer |
| Total Pages | : 175 |
| Release | : 2015-06-15 |
| Genre | : Science |
| ISBN | : 3319199897 |
Download Discovery and Measurement of the Higgs Boson in the WW Decay Channel Book in PDF, Epub and Kindle
This thesis describes the stand-alone discovery and measurement of the Higgs boson in its decays to two W bosons using the Run-I ATLAS dataset. This is the most precise measurement of gluon-fusion Higgs boson production and is among the most significant results attained at the LHC. The thesis provides an exceptionally clear exposition on a complicated analysis performed by a large team of researchers. Aspects of the analysis performed by the author are explained in detail; these include new methods for evaluating uncertainties on the jet binning used in the analysis and for estimating the background due to associated production of a W boson and an off-shell photon. The thesis also describes a measurement of the WW cross section, an essential background to Higgs boson production. The primary motivation of the LHC was to prove or disprove the existence of the Higgs boson. In 2012, CERN announced this discovery and the resultant ATLAS publication contained three decay channels: gg, ZZ, and WW.
| Author | : Brian Moser |
| Publisher | : Springer Nature |
| Total Pages | : 250 |
| Release | : 2023-09-19 |
| Genre | : Science |
| ISBN | : 3031394429 |
Download The Beauty and the Boost: A Higgs Boson Tale Book in PDF, Epub and Kindle
Precision measurements of the Higgs boson’s properties are a powerful tool to look for deviations from the predictions of the Standard Model (SM) of particle physics. The 139/fb of proton-proton collision data which have been collected by the ATLAS experiment during Run 2 of the LHC, offer an opportunity to investigate rare Higgs-boson topologies, which are particularly sensitive to new physics scenarios but experimentally difficult to access. Several such measurements, which target Higgs-boson decays to heavy-flavour quarks, as well as their combinations are presented in this thesis. A novel analysis that measures Higgs-boson production in association with a heavy vector boson V (VH, with V=W,Z) at high energies is presented. Dedicated Higgs-boson reconstruction techniques are applied to reconstruct the highly Lorentz-boosted Higgs-boson decays into pairs of bottom quarks. The measurement is subsequently combined with a VH cross-section measurement at low and intermediate pT(V) to provide a differential cross-section measurement in kinematic fiducial volumes over the largest possible pT(V) range. All cross-section measurements agree with the SM predictions within relative uncertainties that range from 30% to 300%. The results are furthermore interpreted as limits on the parameters of a SM effective field theory. Finally, a combination of measurements of Higgs decays to heavy-flavour quarks is used to experimentally determine that the Higgs-boson coupling to charm quarks is weaker than to bottom quarks, as predicted by the SM. The target audience for the thesis are physicists and physics students, in particular those with a background in high energy physics.
| Author | : Jennet Elizabeth Dickinson |
| Publisher | : |
| Total Pages | : 0 |
| Release | : 2021 |
| Genre | : |
| ISBN | : 9783030863692 |
Download ATLAS Measurements of the Higgs Boson Coupling to the Top Quark in the Higgs to Diphoton Decay Channel Book in PDF, Epub and Kindle
During Run 2 of the Large Hadron Collider, the ATLAS experiment recorded proton-proton collision events at 13 TeV, the highest energy ever achieved in a collider. Analysis of this dataset has provided new opportunities for precision measurements of the Higgs boson, including its interaction with the top quark. The Higgs-top coupling can be directly probed through the production of a Higgs boson in association with a top-antitop quark pair (ttH). The Higgs to diphoton decay channel is among the most sensitive for ttH measurements due to the excellent diphoton mass resolution of the ATLAS detector and the clean signature of this decay. Event selection criteria were developed using novel Machine Learning techniques to target ttH events, yielding a precise measurement of the ttH cross section in the diphoton channel and a 6.3 $\sigma$ observation of the ttH process in combination with other decay channels, as well as stringent limits on CP violation in the Higgs-top coupling.
| Author | : Estelle Scifo |
| Publisher | : |
| Total Pages | : 0 |
| Release | : 2014 |
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| ISBN | : |
Download Measurement of the Brout-Englert-Higgs Boson Couplings in Its Diphoton Decay Channel with the ATLAS Detector at the LHC Book in PDF, Epub and Kindle
After the Higgs boson discovery in the first LHC data, the focus is now on its properties measurement. Among these properties, its couplings are of particular importance since any deviation from the expected value can be an indication of new physics, beyond the Standard Model. This thesis is oriented towards the Higgs couplings measurements with the ATLAS experiment, using the diphoton decay channel. Selected diphoton events are classified into different categories to disentangle the five Higgs production modes by tagging the objects produced in association with the Higgs boson: two jets for the VBF production mode, lepton and missing transverse energy for the higgsstrahlung (WH and ZH), b-jets for ttH, the remaining events being mostly produced via the dominant production mode ggH. The impact of the Higgs pT modelling in the ggH production mode is also investigated. Theoretical developments provide predictions of the pT shape at NNLO+NNLL accuracy, including top and bottom mass effects in the loop up to NLO+NLL, implemented in the HRes program. A reweighting technique to take into account these latest theoretical improvements is derived, taking into consideration the correlation with the number of jets. Its impact on the final measurement is estimated to be of the order of a few percent. The final couplings results, measured at the Higgs mass obtained by the combination of the H->gamma gamma and H->ZZ*->4l channels in ATLAS (mH = 125.4 +/- 0.4 GeV) do not show any statistically significant deviation from the Standard Model. The observed signal strength mu = sigma^{obs} / sigma^{exp} is found to be: mu = 1.17^{+0.28}_{-0.25} = 1.17 +/- 0.23(stat) ^{+0.10}_{-0.08}(syst) ^{+0.12}_{-0.08}(theory). The ratio of the observed number of events in each production mode to the expected ones are measured at: mu_ggH = 1.32 +/- 0.32(stat.) ^{+0.13}_{-0.09}(syst.) ^{+0.19}_{-0.11}(theory) ; mu_VBF = 0.8 +/- 0.7(stat.) ^{+0.2}_{-0.1}(syst.) ^{+0.2}_{-0.3}(theory) ; mu_WH = 1.0 +/- 1.5(stat.) ^{+0.3}_{-0.1}(syst.) ^{+0.2}_{-0.1}(theory) ; mu_ZH = 0.1 ^{+3.6}_{-0.1}(stat.) ^{+0.7}_{-0.0}(syst.) ^{+0.1}_{-0.0}(theory) ; mu_ttH = 1.6 ^{+2.6}_{-1.8}(stat.) ^{+0.6}_{-0.4}(syst.} ^{+0.5}_{-0.2}(theory).
| Author | : Eric Ouellette |
| Publisher | : Springer |
| Total Pages | : 114 |
| Release | : 2015-01-20 |
| Genre | : Science |
| ISBN | : 3319135996 |
Download Search for the Higgs Boson in the Vector Boson Fusion Channel at the ATLAS Detector Book in PDF, Epub and Kindle
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.
