Download or read book Observation of the Standard Model Higgs Boson Produced in Association with a Pair of Top Quarks at sqrt s written by Johannes Donatus Mellenthin and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The top quark is the heaviest elementary particle in the Standard Model and has an expected Yukawa coupling to the Higgs boson of order unity. The value of this coupling is a key ingredient to unravel the nature of the observed Higgs boson. The most favourable production mode that has a direct sensitivity to this coupling is the production of a Higgs boson in association with a top-quark pair, $t\bar{t}H$. This process was observed based on the analysis of proton-proton collision data at $\sqrt{s} = 13 \, \text{TeV}$ recorded with the ATLAS experiment at the LHC. Using data corresponding to ...
Download or read book Observation of the Standard Model Higgs Boson Produced in Association with a Pair of Top Quarks at sqrt s written by Johannes Donatus Mellenthin and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The top quark is the heaviest elementary particle in the Standard Model and has an expected Yukawa coupling to the Higgs boson of order unity. The value of this coupling is a key ingredient to unravel the nature of the observed Higgs boson. The most favourable production mode that has a direct sensitivity to this coupling is the production of a Higgs boson in association with a top-quark pair, $t\bar{t}H$. This process was observed based on the analysis of proton-proton collision data at $\sqrt{s} = 13 \, \text{TeV}$ recorded with the ATLAS experiment at the LHC. Using data corresponding to...
Download or read book Higgs Boson Decays into a Pair of Bottom Quarks written by Cecilia Tosciri and published by Springer Nature. This book was released on 2021-10-22 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: The discovery in 2012 of the Higgs boson at the Large Hadron Collider (LHC) represents a milestone for the Standard Model (SM) of particle physics. Most of the SM Higgs production and decay rates have been measured at the LHC with increased precision. However, despite its experimental success, the SM is known to be only an effective manifestation of a more fundamental description of nature. The scientific research at the LHC is strongly focused on extending the SM by searching, directly or indirectly, for indications of New Physics. The extensive physics program requires increasingly advanced computational and algorithmic techniques. In the last decades, Machine Learning (ML) methods have made a prominent appearance in the field of particle physics, and promise to address many challenges faced by the LHC. This thesis presents the analysis that led to the observation of the SM Higgs boson decay into pairs of bottom quarks. The analysis exploits the production of a Higgs boson associated with a vector boson whose signatures enable efficient triggering and powerful background reduction. The main strategy to maximise the signal sensitivity is based on a multivariate approach. The analysis is performed on a dataset corresponding to a luminosity of 79.8/fb collected by the ATLAS experiment during Run-2 at a centre-of-mass energy of 13 TeV. An excess of events over the expected background is found with an observed (expected) significance of 4.9 (4.3) standard deviation. A combination with results from other \Hbb searches provides an observed (expected) significance of 5.4 (5.5). The corresponding ratio between the signal yield and the SM expectation is 1.01 +- 0.12 (stat.)+ 0.16-0.15(syst.). The 'observation' analysis was further extended to provide a finer interpretation of the V H(H → bb) signal measurement. The cross sections for the VH production times the H → bb branching ratio have been measured in exclusive regions of phase space. These measurements are used to search for possible deviations from the SM with an effective field theory approach, based on anomalous couplings of the Higgs boson. The results of the cross-section measurements, as well as the constraining of the operators that affect the couplings of the Higgs boson to the vector boson and the bottom quarks, have been documented and discussed in this thesis. This thesis also describes a novel technique for the fast simulation of the forward calorimeter response, based on similarity search methods. Such techniques constitute a branch of ML and include clustering and indexing methods that enable quick and efficient searches for vectors similar to each other. The new simulation approach provides optimal results in terms of detector resolution response and reduces the computational requirements of a standard particles simulation.
Download or read book Search for a Standard Model Higgs Boson Produced in Association with a Top quark Pair and Decaying to Bottom Quarks Using a Matrix Element Method written by and published by . This book was released on 2015 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for the Standard Model Higgs Boson Decaying Into B overline b Produced in Association with Top Quarks Decaying Hadronically in Pp Collisions at sqrt s written by and published by . This book was released on 2016 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper, a search for Higgs boson production in association with a pair of top quarks ($ t\overline{t} $H) is performed, where the Higgs boson decays to $ b\overline{b} $ , and both top quarks decay hadronically. The data used correspond to an integrated luminosity of 20.3 fb -1 of pp collisions at √s = 8 TeV collected with the ATLAS detector at the Large Hadron Collider. The search selects events with at least six energetic jets and uses a boosted decision tree algorithm to discriminate between signal and Standard Model background. The dominant multijet background is estimated using a dedicated data-driven technique. For a Higgs boson mass of 125 GeV, an upper limit of 6.4 (5.4) times the Standard Model cross section is observed (expected) at 95% confidence level. The best-fit value for the signal strength is [mu] = 1.6 ± 2.6 times the Standard Model expectation for mH = 125 GeV. Combining all $ t\overline{t}$H searches carried out by ATLAS at √s = 8 and 7 TeV, an observed (expected) upper limit of 3.1 (1.4) times the Standard Model expectation is obtained at 95% confidence level, with a signal strength [mu] = 1.7 ± 0.8.
Download or read book The Higgs Boson Produced With Top Quarks in Fully Hadronic Signatures written by Daniel Salerno and published by Springer Nature. This book was released on 2019-10-25 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work presented in this PhD dissertation is the first search at CMS for Higgs bosons produced in association with top quarks (ttH) in a final state consisting of only jets. The results presented in this book uncover a new class of ttH events that will help us elucidate our understanding of the Yukawa sector interactions between the Higgs boson and the top quark. Despite this being the most common decay signature for ttH, a large contamination of SM backgrounds makes it the most challenging for extracting a signal from data. The PhD thesis presents many sophisticated tools and techniques that were developed in order to overcome these challenges. These tools pave the way for future analyses to investigate other standard model and beyond-standard model physics.
Download or read book Search for the Standard Model Higgs Boson Produced in Association with a Standard W Or a Z Boson and Decaying to Bottom Quarks written by and published by . This book was released on 2014 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for the standard model Higgs boson (H) decaying to b b-bar when produced in association with a weak vector boson (V) is reported for the following channels: W(mu nu)H, W(e nu)H, W(tau nu)H, Z(mu mu)H, Z(e e)H, and Z(nu nu)H. The search is performed in data samples corresponding to integrated luminosities of up to 5.1 inverse femtobarns at sqrt(s) = 7 TeV and up to 18.9 inverse femtobarns at sqrt(s) = 8 TeV, recorded by the CMS experiment at the LHC. An excess of events is observed above the expected background with a local significance of 2.1 standard deviations for a Higgs boson mass of 125 GeV, consistent with the expectation from the production of the standard model Higgs boson. The signal strength corresponding to this excess, relative to that of the standard model Higgs boson, is 1.0 +/- 0.5./abstract
Download or read book A Search for the Standard Model Higgs Boson Produced in Association with Top Quarks written by Jonathan S. Wilson and published by . This book was released on 2012 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: We have performed a search for the Standard Model Higgs boson produced in association with top quarks in the lepton plus jets channel. We impose no constraints on the decay of the Higgs boson. We employ ensembles of neural networks to discriminate events containing a Higgs boson from the dominant di-top background, and set upper bounds on the Higgs production cross section. At a Higgs boson mass mH = 120 GeV/c2, we expect to exclude a cross section 12.7 times the Standard Model prediction, and we observe an exclusion 27.4 times the Standard Model prediction with 95% confidence.
Download or read book Higgs boson potential at colliders status and perspectives written by Biagio Di Micco and published by Roma TrE-Press. This book was released on 2020-12-18 with total page 281 pages. Available in PDF, EPUB and Kindle. Book excerpt: Questo documento riassume lo stato attuale degli ricerche studi, teorici e sperimentali, sulla produzione di coppie di bosoni di Higgs, e sui vincoli, sia diretti che indiretti, al valore del termine di auto-interazione del bosone di Higgs, con l’intento di servire da referenza per i prossimi anni. Il documento discute lo stato degli studi teorici, includendo le più recenti stime della sezione di produzione di coppie di bosoni di Higgs, sviluppi sulle teorie di campo efficaci, e studi su specifici scenari di nuova fisica che possono contribuire alla produzione di due bosoni di Higgs. Sono presentati i più recenti risultati sperimentali sulle ricerche di coppie di bosoni di Higgs e sui limiti diretti e indiretti al termine di auto-interazione, ottenuti al Large Hadron Collider di Ginevra, con una panoramica delle tecniche sperimentali. Infine, sono discusse le capacità dei collisionatori futuri di determinare il termine di auto-interazione del bosone di Higgs. Questo lavoro è iniziato come raccolta di contributi della conferenza “Di-Higgs ai Colliders”, che ha avuto luogo a Fermilab dal 4 al 9 settembre 2018, ma gli argomenti discussi vanno al di là di quelli presentati alla conferenza, includendo ulteriori sviluppi.
Download or read book Observation of Higgs Boson Production in Association with a Top Quark antiquark Pair in the Diphoton Decay Channel written by Samuel James May and published by . This book was released on 2020 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents the first observation of Higgs boson production in association with a top quark-antiquark pair in the diphoton decay channel, with a significance of 6.6 standard deviations. The measurement is performed with a dataset of 13 TeV proton-proton collisions recorded by the Compact Muon Solenoid (CMS) detector at the CERN Large Hadron Collider (LHC), corresponding to an integrated luminosity of 137 fb−1.
Download or read book Search for the Production of the Higgs Boson Associated with a Pair of Top Quarks with the Atlas Detector at the LHC written by Chao Wang and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The production of the Higgs boson associated with a pair of top quarks is one of the most important Higgs boson production modes yet still not observed. Therefore, its discovery is one of the most challenging searches after the Higgs discovery: not only will it be the first time we can observe this Higgs production mode but also we will be able to measure its Yukawa coupling to the top quark. The measured results can answer the basic question of the Standard Model (SM) and can also search for any hints of new physics beyond the SM prediction. An analysis searching for the production of the Higgs boson associated with a pair of top quarks in three leptons final states is presented in this thesis. It is performed with the data collected by the ATLAS detector in 2015 and 2016 during the so-called « Run 2 » campaign corresponding to an integrated luminosity of 36.1 fb−1 at a center of mass energy of 13 TeV. It uses a boosted decision tree algorithm to discriminate between signal and background. The dominant background of fake leptons is estimated with the data-driven matrix method (Matrix Method). For a 125 GeV Standard Model Higgs boson, an excess of events over the expected background from other SM processes is found with an observed significance of 2.2 standard deviations, compared to an expectation of 1.5 standard deviations. The best fit for the ̄ttH production cross section is 1.5+0⋅8−0⋅7 times the SM expectation, consistent with the SM value of the Yukawa coupling to top quarks.
Download or read book Search for the Standard Higgs Boson Produced in Association with a Pair of Top Quark in the Multi leptons Channel in the CMS Experiment written by Xavier Coubez and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The discovery in 2012 of the last elementary particle predicted by the Standard Model, the Higgs boson, has opened a new era in particle physics. One of the objectives now is to probe the coupling of the Higgs boson to other particles in order to confirm the validity of the model. The work of this thesis focused initially on the identification of jets coming from b quark at trigger level. The goal is to allow for the selection of one thousand events among the forty million produced every second at the LHC, by identifiying objects present in the final states of interesting physics processes such as the associated production of a Higgs boson decaying in a pair of b quark with a Z boson decaying into undetected neutrinos. The work then moved to the study of the coupling of the Higgs boson to the quark top, most massive particle in the Standard Model. After a study of one of the important background of the associated production of the Higgs boson and a top quark pair, a new method called matrix element method has been used to improve the discrimination between signal and background. This analysis has led to the first experimental evidence of coupling between the Higgs boson and the top quark.
Download or read book Measurement of Higgs Boson Decay Into B quarks in Associated Production with a Top quark Pair in Pp Collisions at square Root s written by [Study Group] ATLAS Collaboration CERN and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The associated production of a Higgs boson and a top-quark pair is measured in events characterised by the presence of one or two electrons or muons. The Higgs boson decay into a b-quark pair is used. The analysed data, corresponding to an integrated luminosity of 139 fb−1, were collected in proton-proton collisions at the Large Hadron Collider between 2015 and 2018 at a centre-of-mass energy of s√ = 13 TeV. The measured signal strength, defined as the ratio of the measured signal yield to that predicted by the Standard Model, is 0.35+0.36−0.34. This result is compatible with the Standard Model prediction and corresponds to an observed (expected) significance of 1.0 (2.7) standard deviations. The signal strength is also measured differentially in bins of the Higgs boson transverse momentum in the simplified template cross-section framework, including a bin for specially selected boosted Higgs bosons with transverse momentum above 300 GeV
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:
Download or read book The Beauty and the Boost A Higgs Boson Tale written by Brian Moser and published by Springer Nature. This book was released on 2023-09-19 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Search for the Associated Production of the Higgs Boson with a Top quark Pair written by and published by . This book was released on 2014 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for the standard model Higgs boson produced in association with a top-quark pair (t−tH) is presented, using data samples corresponding to integrated luminosities of up to 5.1 fb−1 and 19.7 fb−1 collected in pp collisions at center-of-mass energies of 7 TeV and 8 TeV respectively. The search is based on the following signatures of the Higgs boson decay: H 2!hadrons, H 2!photons, and H 2!leptons. The results are characterized by an observed t−tH signal strength relative to the standard model cross section, [mu]=[sigma]/[sigma]SM, under the assumption that the Higgs boson decays as expected in the standard model. The best fit value is [mu] = 2.8 " 1.0 for a Higgs boson mass of 125.6 GeV.
Download or read book Evidence for a Standard Model Higgs Boson Produced in Association with a Top Quark Pair and Decaying to Leptons written by Charles N. Mueller and published by . This book was released on 2017 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt:
