Дисертації з теми "Higgs couplings"
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Riad, Stella. "Phenomenology of neutrino properties, unification, and Higgs couplings beyond the Standard Model." Doctoral thesis, KTH, Teoretisk partikelfysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-202311.
Повний текст джерелаQC 20170221
Voutsinas, Georgios. "Optimisation of the ILC vertex detector and study of the Higgs couplings." Thesis, Strasbourg, 2012. http://www.theses.fr/2012STRAE053/document.
Повний текст джерелаThis thesis is a contribution to the " Detector Baseline Document ", describing the ILD detector which is intendedfor the International Linear Collider (ILC).The physics goals of the ILD call for a vertex detector (VXD) particularly light, rapid and very granular allowing toreach an unprecedented resolution on the impact parameter of the tracks that reconstruct the particles producedin the studied interactions. The principle goal of this thesis is to show how to optimise the parameters of the VXDin the case that is composed of Active Pixel Sensors manufactured in industrial CMOS technology (CAPS). Thiswork has been realised by studying the sensitivity of the performance of the heavy flavour tagging and theprecision on the hadronic branching fractions of the Higgs boson as a function of different sets of VXDparameters.The specifications of the VXD, particularly ambitious, call for the development of a novel silicon pixel sensorstechnology, the CAPS, which was pioneered by the PICSEL group of IPHC. The readout speed and the influenceof the fabrication parameters have been studied in this thesis, and CAPS prototypes have been characterised intest beams. Finally, the tracking performance of a CAPS based VXD has been evaluated with simulation studies
Stefaniak, Tim [Verfasser]. "Higgs Couplings and Supersymmetry in the Light of early LHC Results / Tim Stefaniak." Bonn : Universitäts- und Landesbibliothek Bonn, 2014. http://d-nb.info/1060787318/34.
Повний текст джерелаCarrington, James Michael. "Vacuum stability of the standard model and BSM extensions." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/8851.
Повний текст джерелаHuckvale, Benedict James. "Studying anomalous WWγ couplings and developing the global calorimeter trigger control system for the CMS experiment". Thesis, University of Bristol, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505753.
Повний текст джерелаGoudet, Christophe. "Calibration of the Electromagnetic Calorimeter of the ATLAS Experiment and Application to the Measurement of (BE)H Boson Couplings in the Diphoton Channel with Run 2 Data of the LHC." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS304/document.
Повний текст джерелаThe discovery of the Higgs boson was a major success of the run 1 of the LHC. The era of precision measurements began as any deviation from the expected Standard Model value would be a direct hint of new physics beyond the standard model. This thesis has a first focus on the calibration of the electromagnetic calorimeter of the ATLAS experiment. The final step of this calibration uses the knowledge of the line shape of the Z boson in order to correct the measured energy of electrons and photons. Recommendations for the beginning of run 2 have been given to provide calibration constants for early analyses. Run 2 calibration constants have been computed and the performances of run 1 have been reached and improved : the systematic uncertainty on the resolution constant term of the electromagnetic calorimeter, which was dominant for the Higgs boson couplings measurement at run 1, has been divided by a factor 3.The measurement of the H boson couplings consists in measuring the shape of the resonant signal over a smooth decreasing background in categories optimized for various processes, by tagging the objects produced in association with the Higgs boson. The results are based on 36 fb$^{-1}$ of data recorded in 2015 and 2016 at $sqrt{s}$=13 TeV. The ratio of the measured production cross-sections of the Higgs boson over the SM expected value ($mu$) has been measured. No significant deviation with respect to the SM has been observed.$$mu = 0.99 pm 0.14$$The ratios of the main production processes have also been measured:$$mu_{ggH} = 0.80 pm 0.18$$$$mu_{VBF} = 2.1 pm 0.66$$$$mu_{VH} = 0.7 pm 0.85$$$$mu_{ttH+tH} = 0.5 pm 0.62$$
Biekötter, Anke [Verfasser], and Tilman [Akademischer Betreuer] Plehn. "Know its limits - A global view on Higgs couplings at the LHC / Anke Biekötter ; Betreuer: Tilman Plehn." Heidelberg : Universitätsbibliothek Heidelberg, 2019. http://d-nb.info/1192373111/34.
Повний текст джерелаScifo, Estelle. "Measurement of the Brout-Englert-Higgs boson couplings in its diphoton decay channel with the ATLAS detector at the LHC." Phd thesis, Université Paris Sud - Paris XI, 2014. http://tel.archives-ouvertes.fr/tel-01064955.
Повний текст джерелаDelgove, David. "Mesure des propriétés du boson de Higgs avec l'expérience ATLAS au LHC." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS316/document.
Повний текст джерелаIn this thesis, I show my contribution to the study of the properties of the Higgs boson. My work has consisted in combining the different searches of the Standard Model Higgs boson to measure the rate of production, decay and the couplings. For example, the overall rate of production measured with the ATLAS dectector has been measured. These measurements can also be interpreted in the constext of models beyond the standard model such that composite models or models inspired from the MSSM (hMSSM). I have also participated to the studies of the performance of a particle flow algorithm to reconstruct the jet with a large radius. My contribution to the search of a pseudoscalar Higgs boson decaying into a Z boson and a Higgs boson and the search of the standard model Higgs boson produced in association with a Z boson and decaying into a pair of b quarks are also shown
Hackstein, Christoph [Verfasser], and G. [Akademischer Betreuer] Quast. "Searches for the Higgs Boson at the LHC Based on its Couplings to Vector Bosons / Christoph Hackstein. Betreuer: G. Quast." Karlsruhe : KIT-Bibliothek, 2011. http://d-nb.info/1014279445/34.
Повний текст джерелаGhosh, Aishik. "Simulation of the ATLAS electromagnetic calorimeter using generative adversarial networks and likelihood-free inference of the offshell Higgs boson couplings at the LHC." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASP058.
Повний текст джерелаSince the discovery of the Higgs boson in 2012, experiments at the LHC have been testing Standard Model predictions with high precision measurements. Measurements of the off-shell couplings of the Higgs boson will remove certain degeneracies that cannot be resolved with the current on-shell measurements, such as probing the Higgs boson width, which may lead to hints for new physics. One part of this thesis focuses on the measurement of the off-shell couplings of the Higgs boson produced by vector boson fusion and decaying to four leptons. This decay channel provides a unique opportunity to probe the Higgs in its off-shell regime due to enhanced cross-sections beyond 2Mz (twice the mass of the Z boson) region of the four lepton mass. The significant quantum interference between the signal and background processes renders the concept of `class labels' ill-defined, and poses a challenge to traditional methods and generic machine learning classification models used to optimise a signal strength measurement. A new family of machine learning based likelihood-free inference strategies, which leverage additional information that can be extracted from the simulator, were adapted to a signal strength measurement problem. The study shows promising results compared to baseline techniques on a fast simulated Delphes dataset. Also introduced in this context is the aspiration network, an improved adversarial algorithm for training while maintaining invariance with respect to chosen features. Measurements in the ATLAS experiment rely on large amounts of precise simulated data. The current Geant4 simulation software is computationally too expensive to sustain the large amount of simulated data required for planned future analyses. The other part of this thesis focuses on a new approach to fast simulation using a Generative Adversarial Network (GAN). The cascading shower simulation of the complex ATLAS calorimeter is the slowest part of the simulation chain using Geant4. Replacing it with a neural network that has learnt the probability distribution of the particle showers as a function of the incident particle properties and local detector geometry increases the simulation speed by several orders of magnitude, even on single core CPUs, and opens to door the further speed up on GPUs. The integration into the ATLAS software allows for the first time to make realistic comparisons to hand-designed fast simulation frameworks. The study is performed on a small section of the detector (0,20<|η|<0,25) using photons and compares distributions using samples simulated by the model standalone as well as after integration into the ATLAS software against fully simulated Geant4 samples. Important lessons on the merits and demerits of various strategies, benefit the ultimate goal of simulating the entire ATLAS calorimeter with a few deep generative models. The study also reveals an inherent problem with the popular gradient penalty based Wasserstein GAN, and proposes a solution
Burgard, Carsten D. [Verfasser], Karl [Akademischer Betreuer] Jakobs, Gregor [Akademischer Betreuer] Herten та Stefan [Akademischer Betreuer] Dittmaier. "Measurement of H→WW→lνlν decays at √s=13 TeV with the ATLAS experiment and analysis of effective Higgs Boson couplings". Freiburg : Universität, 2017. http://d-nb.info/1149507853/34.
Повний текст джерелаLaudrain, Antoine. "Layer Intercalibration of the ATLAS Electromagnetic Calorimeter and CP-odd Higgs Boson Couplings Measurements in the Four-Lepton Decay Channel with Run 2 Data of the LHC." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS341.
Повний текст джерелаAfter the Higgs boson discovery at the LHC in 2012, interest turned to Higgs boson property measurements to refine the tests of the Standard Model and probe for new physics. One of its key properties is its spin-parity (CP), predicted to be 0+ in the Standard Model. Analyses of data collected during the Run 1 of the LHC rejected all pure spin-parity (CP) state other than 0+. However mixed CP states are still possible, and would indicate CP violation in the Higgs sector.The first part of this thesis focuses on the ATLAS electromagnetic calorimeter calibration, needed to reach a permil level on electron and photon energy resolution which are of prime importance for Higgs boson studies. One step of the calibration sequence consists of the layer intercalibration of the electromagnetic calorimeter, needed to correct residual electronics miscalibration and cross-talk effects. The Run 1 method has proven to be unreliable for the pileup levels in Run 2 and a new method was developed, ensuring a precise control on the systematic uncertainties.The second part of this thesis puts emphasis on the Higgs boson to vector boson CP-odd couplings, with the Higgs boson decaying to four leptons. This channel, despite low statistics, provides a clean signature and a signal-to-noise ratio over two, allowing for a precise determination of the Higgs boson properties. The vector boson fusion production channel offers the best sensitivity to CP effects thanks to its two characteristic tagging jets in the final state. The contamination from the gluon fusion production mode with additional jets is reduced using neural networks. To unambiguously distinguish yet unknown CP-even from possible CP-odd effects, a variable whose shape asymmetry only depends on CP-odd effects is built. This observable is based on the matrix element computation, maximally using the kinematic information available from Higgs boson and associated jets. Results are interpreted in a context of effective field theory, and the statistical precision on the tCzz Wilson coefficient is estimated to [-0.80, 0.80] at the 68% confidence level
Faltermann, Nils [Verfasser], and T. [Akademischer Betreuer] Müller. "Single Top Quark Production at 13 TeV with the CMS Experiment: from Rediscovery to Search for Rare Channels and Determination of Higgs Boson Couplings / Nils Faltermann ; Betreuer: T. Müller." Karlsruhe : KIT-Bibliothek, 2018. http://d-nb.info/1167309057/34.
Повний текст джерелаRonqui, Caique Meira. "Hierarquia e naturalidade, uma visão completa do problema e suas possíveis soluções." Universidade Estadual Paulista (UNESP), 2018. http://hdl.handle.net/11449/153392.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Elaboramos uma revisão de como o problema da hierarquia aparece na teoria Eletrofraca, pois entendemos que esse assunto ganhou importância e merece atenção especial. Apesar disso, notamos que muitos conceitos necessários para compreender a origem do problema encontram-se espalhados em diferentes livros e artigos, dificultando o acesso à informação. Por isso, apresentamos neste trabalho esses principais conceitos de maneira consolidada.
We develop a review on how the hierarchy problem appears in the Electroweak theory. Nowadays we think that this problem is greater in importance than it was in the past, so it deserves special attention, but we noticed several concepts needed to understand the problem are scattered in different books and papers, which hinders full access to information. Therefore, we intend to present the key subjects in a single document, because we didn't find similar work in previous studies.
2015/19572-0
Kaluza, Adam [Verfasser]. "The Effective Lagrangian Morphing and the Measurement of Effective Higgs Boson Couplings in VBF H→W±W∓*→ℓ-ν¯ℓℓ'+νℓ' at s=13 TeV with the ATLAS Experiment / Adam Kaluza". Mainz : Universitätsbibliothek Mainz, 2020. http://d-nb.info/1214311091/34.
Повний текст джерелаLorenzo, Martinez Narei. "Observation of a Higgs boson and measurement of its mass in the diphoton decay channel with the ATLAS detector at the LHC." Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00924105.
Повний текст джерелаPasterski, Sabrina Gonzalez. "Measuring Higgs self-coupling at CMS." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/83802.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (page 43).
This study evaluates the Compact Muon Solenoid (CMS) experiment's ability to characterize Higgs self-coupling through the ... channel. The effective cross-section for detecting ... events is computed by finding the fraction of simulated events that make it through selection cuts. These same cuts also are applied to simulated background samples. The result is then compared to a recent theoretical study on measuring Higgs self-coupling to check the applicability of its assumptions and the feasibility of its predictions. This study finds that the selection algorithms currently used for ... analyses at CMS produce a lower yield of signal events. Since the ... channel was predicted to be one of the most promising for characterizing the Higgs self-coupling constant, ... , the results of this study indicate that, unless the methods for reconstructing detected particles are improved, future data collected by CMS will not be sufficient to complete such an analysis.
by Sabrina Gonzalez Pasterski.
S.B.
Li, Shu. "Mesure de la production W+W− dans les collisions proton-proton à $\sqrt{s} = 7 TeV avec le détecteur ATLAS au LHC." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4107.
Повний текст джерелаThis thesis presents a measurement of the SM WW production cross section and the determination of the corresponding limits on anomalous triple gauge boson couplings (aTGCs), using the 2011 4.7 fb⁻¹ pp collisions data at 7 TeV collected in 2011. The measurement allows for a stringent test of the non-Abelian SU(2) X U(1) SM electroweak sector and probes new physics that could manifest itself through aTGCs that may alter the observed production cross section or kinematic distributions. This measurement also provides a good understanding of the irreducible background in searches for the Higgs boson through the H → W⁺W⁻ decay channel.This thesis work has laid a solid foundation for further measurements of the WW production with the ∼25 fb⁻¹ integrated luminosity 8 TeV recorded data expected by the end of 2012, which will further improve the precision and yield more stringent limits on the aTGCs
Schildt, Erik. "Higgs inflation." Thesis, Uppsala universitet, Teoretisk fysik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-355063.
Повний текст джерелаI detta projekt undersöker vi en modell av kosmisk inflation där Higgsfältet med en ickeminimal koppling till tyngdkraften är mekanismen bakom inflation. Vi utför en klassisk analys och beräknar modellens föresägelser för ett antal kosmologiska parametrar som jämförs med Planck experimentet. Vi uppskattar värdet på den ickeminimala kopplingen $\xi$ och finner att $\xi \sim 10^4$. De grundläggande aspekterna bakom kvantanalysen samt vad effekten av den ickeminimala kopplingen har på beskrivningen i termer av en effektiv fältteori diskuteras. Vi finner att en klassisk analys ger förutsägelser som passar väl med Planckexperimentet men att den ickeminimala kopplingen leder till unitaritetsproblem för denna modell av inflation. Kvanteffekter kan dock ha en avsevärd effekt på resultat och en utförlig analys som tar dem till hänsyn krävs för att avgöra om Higgsinflation är en möjlig modell för inflation.
Strebler, Thomas. "Probing the Higgs coupling to the top quark at the LHC in the CMS experiment." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLX044/document.
Повний текст джерелаThis thesis reports a study of the Higgs boson production in association with top quarks and decaying into τ leptons in proton-proton (pp) collisions at a center-of-mass energy of sqrt(s) = 13 TeV recorded with the CMS detector at the CERN Large Hadron Collider (LHC).This work has been carried out in the context of the Run 2 of the LHC, marked by an increase in the center-of-mass energy from 8 to 13 TeV together with an increase in the instantaneous luminosity of the collisions with respect to Run 1. To cope with this new data-taking conditions, CMS had initiated a full upgrade of the Level-1 trigger system achieved by 2016. This new system and in particular the new Level-1 electron and photon algorithm have successfully contributed to a large number of CMS results using Run 2 data. The commissioning of this new system and its performance measured with the first data collected with this new trigger are presented in details.A novel analysis technique based on the Matrix Element Method optimized for the search of the ttH, H->tautau process is also presented, including several generic tools which can be used in a large variety of H->tautau analyses. Results of the CMS analysis using this method based on 35.9 fb-1 collected in 2016 are presented. The background-only hypothesis is disfavored but not yet excluded by this analysis alone
Faucci, Giannelli Michele. "Measuring of the Higgs self-coupling at an electron-positron linear collider." Thesis, Royal Holloway, University of London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.502603.
Повний текст джерелаMeineck, Christian. "Coupling measurement of the Higgs boson and search for heavy Higgs like bosons via the decay channel \hwwlnln with the ATLAS experiment." Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-178250.
Повний текст джерелаTwo analyses of the decay channel \hwwlnln using the data of the ATLAS experiment at LHC are presented here. The data was recorded in the years 2011 and 2012 with a center of mass energy of $\sqrt{s} = 7 \TeV$ and $8 \TeV$, respectively, with a total integrated luminosity of $25\,\textrm{fb}^{-1}$ reached. The two presented analyses differ in the analyzed phase space, which depends on the mass $m_{\rm H}$ of the analyzed Higgs boson signal. The analysis for masses $m_{\rm H} < 200 \GeV$ is optimized to perform a high precision measurement of the couplings of the resonance at $m_{\rm H} \approx 125 \GeV$. A binned likelihood fit of the transverse mass distribution $\mT = \sqrt{ (E_{T}^{\ell \ell} + P_{T}^{\nu \nu})^2 - | \vec{P_{T}^{\ell \ell}} + \vec{P_{T}^{\nu \nu}|^2} }$ is used to obtain the results. A signal originating from a Standard Model Higgs boson with a mass $m_{\rm H} = 125.36 \pm 0.41 \GeV$ has been observed at a statistical significance of $6.1 \sigma$. The signal strength, defined as the ratio of the measured production cross section times branching ratio over the theoretical prediction, is: \begin{align*} \mu &= 1.08\,^{+0.16}_{+0.15} \textrm{(stat.)} \,^{+0.16}_{-0.14} \textrm{(syst.)}, \end{align*} which is in good agreement with the data and with the Standard Model prediction. The scaling factors of the couplings of the Higgs boson to fermions and bosons have been measured as: \begin{align*} \kappa_{F} &= 0.92\,^{+0.30}_{-0.23}\\ \kappa_{V} &= 1.04\,^{+0.10}_{-0.11}, \end{align*} which is also in good agreement with the Standard Model prediction. In order to search for heavier Higgs like particles, the analysis of \hwwlnln decays is also optimized for masses $m_{\rm H} \geq 200 \GeV$. As in the analysis optimized for $m_{\rm H} < 200 \GeV$, a binned likelihood fit of the transverse mass \mT is used. Upper limits on the product of production cross section and branching ratio have been obtained for three scenarios: Standard Model Higgs boson in the mass range $200 \leq m_{\rm H} \leq 1 \TeV$, a Higgs like particle with a decay width of $1 \GeV$ in the mass range $200 \leq m_{\rm H} \leq 2 \TeV$ and the electroweak singlet scenario in the mass range $200 \leq m_{\rm H} \leq 1 \TeV$ with the decay width being an additional free parameter. No statistically significant excess of the observed data over the expectation is observed, and a heavy Standard Model Higgs boson is excluded up to a mass of $m_{\rm H} = 661 \GeV$.
Jeske, C. "Evidence for the Higgs boson Yukawa coupling to tau leptons with the ATLAS detector." Thesis, University of Warwick, 2015. http://wrap.warwick.ac.uk/77753/.
Повний текст джерелаMildner, Hannes [Verfasser], and U. [Akademischer Betreuer] Husemann. "Measurements of the Top-Higgs Coupling with the CMS Experiment / Hannes Mildner ; Betreuer: U. Husemann." Karlsruhe : KIT-Bibliothek, 2016. http://d-nb.info/1124903038/34.
Повний текст джерелаMegy, Théo [Verfasser], and Christian [Akademischer Betreuer] Weiser. "Measurement of the Higgs-boson coupling to tau-leptons and combined measurements of Higgs-boson properties at sqrt(s) = 13 TeV with the ATLAS detector." Freiburg : Universität, 2019. http://d-nb.info/1198110104/34.
Повний текст джерелаLi, Yichen. "Observation of the Higgs boson and measurement of its properties in the HWW* channel with the ATLAS detector at the LHC." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112046/document.
Повний текст джерелаThe Higgs boson decays to WW* is observed based on an excess of events over background of 6.1 standard deviations in the dilepton final state including all flavour channels (ee/μμ and eμ/μe) and jet multiplicity categories (nj = 0, 1,≥ 2), where theStandard Model expectation is 5.8 standard deviations. Evidence for thevector-boson fusion (VBF) production process is also obtained with a significance of3.2 standard deviations. The different favour channels eμ/μe have the best expected signal sensitivity. The low jet multiplicity categories are dominantly contributed by the gluon-gluon fusion (ggF) production process whereas the large jet multiplicity category has the best sensitivity to the VBF production process. The results are obtained from proton-proton collision data recorded by the ATLAS detector at the LHC, corresponding to 4.5fb-1 at √s = 7TeV and 20.3fb-1 at √s = 8TeV. The background contribution in each channel and jet multiplicity category varies and is determined mostly with data-driven techniques with dedicated control or validation regions. The dominant background processes are the continuum WW and top quark productions. In the same flavour channels (ee/μμ), the Drell-Yan process is another important background source. For a Higgs boson mass of 125.36GeV, the ratio of the measured value to the expected value of the total production cross section times branching ratio 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 modes 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 √s = 8TeV, the total production cross section is measured to beσ(gg → H → WW∗) = 4.6±0.9 (stat.)+0.8−0.7 (syst.) pb σ(VBFH → WW∗) = 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 zero and one associated jet. In addition to the on-shell couplings, other properties of the Higgs boson, namely the spin quantum number and the total decay width, are also studied using the 8TeV data and the different flavour channels only. The spin study is based on the on-shell dominated event sample using the nj ≤ 1 jet categories. The Standard Model spin-parity JCP = 0++ hypothesis is compared with alternative hypotheses. The data are found to be consistent with the Standard Model and limits are placed on alternative spin hypotheses.The off-shell events in the high mass tail from the inclusive jet category are then used to measure the off-shell couplings and impose a constraint on the upper limit of the total width of the Higgs boson indirectly, when certain assumptions are made
Machet, Martina. "Higgs boson production in the diphoton decay channel with CMS at the LHC : first measurement of the inclusive cross section in 13 TeV pp collisions, and study of the Higgs coupling to electroweak vector bosons." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS254/document.
Повний текст джерелаIn this document two analyses of the properties of the Higgs boson in the diphoton decay channel with the CMS experiment at the LHC (Large Hadron Collider) are presented.The document starts with a theoretical introduction of the Standard Model and the Higgs boson physics, followed by a detailed description of the CMS detector.Then, photon reconstruction and identification algorithms are presented, with a particular focus on the differences between the first and the second run of the LHC, the first run (Run1) took place from 2010 to 2012 with a centre-of-mass energy of 7 and then 8 TeV, while the second run (Run2) started in 2015 with a centre-of-mass energy of 13 TeV. Performances of Run1 and Run2 reconstructions from the photon identification point of view are compared. Then the photon identification algorithm for the H->γγ analysis optimised for Run2 is presented. To do that a multivariate analysis method is used. Performances of the photon identification at 13 TeV are finally studied and a data-simulation validation is performed.Afterwards, the H->γγ analysis using the first Run2 data is presented. The analysis is performed with a dataset corresponding to an integrated luminosity of 2.7/fb. An event classification is performed to maximize signal significance and to studyspecific Higgs boson production modes. The observed significance for the standard model Higgs boson is 1.7 sigma, while a significance of 2.7 sigma is expected.Finally a feasibility study, having the aim of constraining the anomalous couplings of the Higgs boson to the vector bosons, is presented. This analysis is performed using the data collected at 8 TeV during Run1 at the LHC, corresponding to an integrated luminosity of 19.5/fb. This analysis exploits the production of the Higgs boson through vector boson fusion (VBF), with the Higgs decaying to 2 photons. The kinematic distributions of the dijet and diphoton systems, which depend from the spin-parity hypothesis, are used to build some discriminants able to discriminate between different spin-parity hypotheses. These discriminants allow to define different regions of the phase-space enriched with a certain spin-parity process. The Higgs boson signal yield is extracted in each region from a fit to the diphoton mass, allowing to determine the contributions of the different processes and then constrain the production of a pseudo-scalar (spin-parity 0-) Higgs boson
Comandini, Devis. "Prospects for the Higgs boson self-coupling measurement with the Phase-II CMS detector upgrade using simulated pp collisions at √s = 27 TeV (High Energy LHC)." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/18478/.
Повний текст джерелаMeineck, Christian [Verfasser], та Johannes [Akademischer Betreuer] Elmsheuser. "Coupling measurement of the Higgs boson and search for heavy Higgs like bosons via the decay channel H → WW(*) →lνlν with the ATLAS experiment / Christian Meineck. Betreuer: Johannes Elmsheuser". München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2014. http://d-nb.info/1065611129/34.
Повний текст джерелаBruscino, Nello [Verfasser]. "A gateway to new physics: direct measurement of the top Yukawa coupling to the Higgs boson / Nello Bruscino." Bonn : Universitäts- und Landesbibliothek Bonn, 2017. http://d-nb.info/1149154373/34.
Повний текст джерелаCoubez, Xavier. "Search for the standard Higgs boson produced in association with a pair of top quark in the multi-leptons channel in the CMS experiment." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAE049/document.
Повний текст джерелаThe 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
Da, Silva Caroline Dos Santos. "Cosmic strings and scalar tensor gravity." Thesis, Durham University, 1999. http://etheses.dur.ac.uk/4577/.
Повний текст джерелаTabassam, Hajrah. "Physics studies at a future linear collider." Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/5858.
Повний текст джерелаOlivares, Sebastian Andres. "Measurement of the Higgs boson off-shell coupling to constrain the total width in the H → ZZ(*) → 4ℓ channel and Level-1 Track muon isolation performance for the HL-LHC with the ATLAS detector". Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/25378.
Повний текст джерелаZhang, Huaqiao. "Analyse ttH,H->WW avec ATLAS au LHC et étude des électron à Très Basses énergie dans le Test Faisceau Combiné 2004." Phd thesis, Université de la Méditerranée - Aix-Marseille II, 2008. http://tel.archives-ouvertes.fr/tel-00443806.
Повний текст джерелаEcker, Katharina Maria [Verfasser], Hubert [Akademischer Betreuer] Kroha, Hubert [Gutachter] Kroha, and Lothar [Gutachter] Oberauer. "Measurement of the Higgs boson tensor coupling in H→ZZ*→4l decays with the ATLAS detector : How odd is the Higgs boson? / Katharina Maria Ecker ; Gutachter: Hubert Kroha, Lothar Oberauer ; Betreuer: Hubert Kroha." München : Universitätsbibliothek der TU München, 2018. http://d-nb.info/1161846999/34.
Повний текст джерелаAgaras, Merve Nazlim. "Searches for associated Higgs Boson production with top quark pair and Higgs pair production in multi lepton final states with the ATLAS detector." Thesis, Université Clermont Auvergne (2017-2020), 2020. http://www.theses.fr/2020CLFAC023.
Повний текст джерелаSince the discovery of the Higgs boson at a mass around 125 GeV by both ATLAS and CMS collaborations in July 2012, it became crucial to measure its properties, such as its couplings to other particles, and search for any deviations from the Standard Model (SM) predictions. The top quark Yukawa coupling is close to unity and the strongest in the fermionic sector. Therefore, this coupling plays a crucial role in the theory. Determination of the associated production of The Higgs boson production with a pair of top quarks (ttH) offers a tree-level access to measuring this coupling. The analysis of ttH production at ATLAS experiment exploits several Higgs decay channel, together with different top quark decay modes. In this thesis, the study of the ttH (H → Multi lepton) process is presented in the topology where the Higgs decays to WW,ZZ or tautau, using a dataset corresponding to an integrated luminosity of 79.8fb^-1 at √s = 13 TeV, collected with the ATLAS detector between 2015-2017. Improved knowledge on the background modelling and the complex fit model is used with many degrees of freedoms. Particularly different fit setups are presented in order to understand the modelling of the major irreducible background, ttW. Furthermore, a search for the SM Higgs boson pair production in the multi lepton final states is presented. The search uses 139fb^-1 of proton-proton collisions data at a centre-of-mass energy of 13 TeV provided by the Large Hadron Collider (LHC) and recorded by the ATLAS experiment in 2015 and 2018. The first studies in two lepton same-sign channel is performed for lepton working point optimisation and estimation of background contributions. Template fit method is applied to estimated the reducible backgrounds and preliminary expected upper limit is calculated
Price, Tony. "Digital calorimetry for future e⁺e⁻ linear colliders and their impact on the precision measurement of the top Higgs Yukawa coupling." Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/4515/.
Повний текст джерелаZhang, H. "Analyse ttH, H EN WW avec ATLAS au LHC et étude des électrons à très basses énergie dans le test faisceau combiné 2004." Phd thesis, Université de la Méditerranée - Aix-Marseille II, 2008. http://tel.archives-ouvertes.fr/tel-00366852.
Повний текст джерелаQin, Yang. "Search for tt̄H production and measurement of the tt̄ cross-section with the ATLAS detector." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/search-for-tbarth-production-and-measurement-of-the-tbart-crosssection-with-the-atlas-detector(1c05f62c-67ad-4011-802d-703d045490f1).html.
Повний текст джерелаHadef, Asma. "Recherche de la production du boson de Higgs en association avec une paire de quarks top dans les canaux avec deux leptons de même charge à partir du détecteur ATLAS au LHC." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0230/document.
Повний текст джерелаThe Large Hadron Collider (LHC) at CERN restarted in spring 2015 for three years (Run2) at an unexplored center-of-mass energy of 13 TeV. A precise measurement of electron reconstruction efficiency in ATLAS, one of the two general purpose experiments of the LHC, is presented in the first part of this thesis with $Zee$ data sample recorded in 2015. This allows to extract scale factors between data and simulation that are used by all ATLAS physics analyses involving electrons. The results show the high ability of the ATLAS detector to reconstruct electrons from one hand and the good understanding of its performance on the other hand. The second part of the thesis is dedicated to a search for the Higgs boson production in association with a top quark pair (ttH), which could allow a first direct measurement of the top quark Yukawa couplingand could reveal new physics. The signature with two same-charge light leptons (electron or muon) without a hadronically decaying tau lepton final state is examined using the first 10% of the total expected Run2 dataset. Events with fake (non-prompt) leptons represent the main reducible background of this signature. An improved method to estimate it has been developped and is discussed in details in this thesis. Driving the total error, fake leptons background is found to be 1.5 to 3.6 times higher than in simulation and represent between 32 and 48% of the total background. The best-fit value of the ratio of observed and Standard Model cross sections of ttH production process, combining with other multilepton channels, is 2.5±0.7(stat)+1.1-0.9(syst), and an upper limit on this ratio of 4.9 (2.3 expected) is found at 95% confidence level
Nechansky, Filip. "Search for the production of a Higgs boson decaying into a pair of bottom quarks in association with a pair of top quarks at 13 TeV with the ATLAS detector." Doctoral thesis, Humboldt-Universität zu Berlin, 2021. http://dx.doi.org/10.18452/23027.
Повний текст джерелаThe discovery of the Higgs Boson in 2012 confirms the Standard Model as the most successful theory describing the fundamental interactions of elemental particles. One of the important properties of the Higgs boson is its Yukawa coupling to the top quark, which in the Standard Model is the strongest due to the high mass of the quark. This thesis reports on a measurement of the top-Yukawa coupling with data collected by the ATLAS detector from 2015 to 2018 at 13 TeV center of mass energy. The coupling is studied in ttH(bb) events, a final state containing decay products of two top quarks with additional emission of a Higgs boson, where the Higgs decays into a pair of bottom quarks. This decay channel of the Higgs Boson has the largest branching ratio, but is systematically limited by the description of the dominant background process ttbb, a tt with additional two b quarks in the final state. The measurement takes advantage of the ability of the ATLAS detector to identify jets coming from a b quarks to construct analysis regions with various compositions of the signal and the background. To further separate the signal, a series of multivariate algorithms is employed and the ttH process is then extracted using a profile likelihood fit. The results are shown for the channel with a single lepton in the final state and for a combination with the dilepton channel. The background performance is studied in detail, where large mis-modeling is found. The measured ratio of the ttH production compared to the Standard Model prediction is found to be mu(ttH) = 0.84 +0.45 -0.39 (syst.) +-0.21 (stat.). The result is in agreement with the Standard Model prediction and corresponds to an observed (expected) significance of 1.9 sigma (2.3 sigma), an improvement compared to the previous ATLAS measurement which reported 1.4 sigma (1.6 sigma).
Chomont, Arthur. "Etude du couplage du quark top au boson de Higgs dans l'expérience ATLAS." Thesis, Université Clermont Auvergne (2017-2020), 2017. http://www.theses.fr/2017CLFAC082/document.
Повний текст джерелаDiscovery of Higgs boson at LHC in 2012 is the most recent confirmation of the validity of Standard Model, theory describing elementary particles and their interactions. Many analysis now target the extraction of properties of the newly-discovered particle. A direct measurement in the ATLAS experiment of the top Yukawa coupling, one of these properties, is targeted in this work through ttH process. This coupling is of particular interest because of its strong sensitivity to New Physics. The first part of the work is about the automation of the calibration of the hadronic tile calorimeter of the ATLAS detector. A detailed description of the laser system used for a regular calibration of the calorimeter is done as well as of the calibration itself. Then more details on the algorithm written for the automation of the calibration are given. The final goal of this algorithm is to ease and fasten the calibration of channels with gain variation. The second part is dedicated to the search for ttH process through multilepton final states with emphasis on final state with two same-sign leptons, at least four jets and at least 1 b-tagged jet. Estimation of reducible backgrounds and statistical treatment of the analysis are detailed. A first version of the analysis with 13.2f b −1 , corresponding to 2015 and mid-2016 LHC data, ends with a final precision too low to extract any conclusion on the tt̄H process. In a second version of the analysis, improvements are made using multivariate analysis and adding more signal regions. The results from the multilepton analysis is combined with results from other ttH analysis, targeting other Higgs decays, to attain a final observed sentivity of 4.2σ. Thus an evidence for ttH production can be claimed from this combination. The final results give good agreement with Standard Model prediction
Fink, Simon [Verfasser], and Th [Akademischer Betreuer] Müller. "Probing the Top-Yukawa Coupling by Searching for Associated Higgs Boson Production with a Single Top Quark at the CMS Experiment / Simon Fink. Betreuer: Th. Müller." Karlsruhe : KIT-Bibliothek, 2016. http://d-nb.info/1110969635/34.
Повний текст джерелаLambrou, Eliana. "Phase structure of five-dimensional anisotropic lattice gauge theories." Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/19579.
Повний текст джерелаWalbrecht, Verena Maria [Verfasser], Hubert [Akademischer Betreuer] Kroha, Hubert [Gutachter] Kroha, and Stefan [Gutachter] Schönert. "Measurement of the Higgs Boson Coupling Structure in Decays to Four Leptons with the ATLAS Detector / Verena Maria Walbrecht ; Gutachter: Hubert Kroha, Stefan Schönert ; Betreuer: Hubert Kroha." München : Universitätsbibliothek der TU München, 2020. http://d-nb.info/1209673444/34.
Повний текст джерелаMartin, perez Cristina. "Development of tau selection techniques for the Higgs boson produced associated to a pair of top quarks and decaying into tau leptons." Thesis, Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAX065.
Повний текст джерелаThe CMS (Compact Muon Solenoid) experiment aims at studying the results of proton collisions produced by the LHC (Large Hadron Collider) at CERN. The discovery of the Higgs boson is a great leap forward as the corresponding mechanism states that particles masses are the result of an interaction with the associated scalar field. The nature of that field is being studied in details and this will occupy the CMS collaborators for the next years. The characterization of the Higgs sector as well as the search for new physics will require the full capabilities of the LHC. Upgrades have been done along the way to reach much higher luminosities (>5x1034cm-2s-1). The CMS experiment deploys a 14000 tones detector equipped with advanced electronics to track and identify precisely all the particles produced from the collisions. Although CMS showed an excellent performance, it underwent upgrades, which include a new data acquisition system to fully exploit high luminosity conditions.The thesis work focuses on taking advantage of the newer analysis and selection techniques to search for tau leptons coming from Higgs which was produced associated to two tops (ttH). The ttH production mode is important to characterize the properties of the Higgs boson and in particular its coupling to top quarks, to which the ttH process has direct access. The Higgs to tau leptons is of particular interest as it probes the Higgs coupling to fermions. Given the mass of the Higgs, the tau decay mode is certainly favored but still represents challenging aspects in both selection and reconstruction techniques. The ttH analysis is particularly challenging given the complexity of final states and makes use of the latest signal extraction techniques. Since its observation in 2018, this analysis is one of the main priorities of the CMS experiment, and the Cristina Martin Perez plays a major role in the full Run 2 legacy paper preparation.Besides, this thesis focuses on the development of a dedicated tau selection algorithm, which had never been achieved with the electronics layers of the data acquisition system. A new trigger system was commissioned with proton collisions data and is being used as the baseline system starting 2016. Cristina Martin Perez plays a leading role in the performance studies and optimization of this trigger
Eble, Florian. "Prospective study for the development of an analysis to measure the tri-linear Higgs coupling using the Matrix Element Method with the ATLAS experiment at the HL-LHC." Thesis, KTH, Fysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-291100.
Повний текст джерелаFlöh, Kevin [Verfasser], and T. [Akademischer Betreuer] Müller. "Investigation of the Top Quark Yukawa Coupling in Higgs Boson Production in Association with Top Quarks at 13 TeV with the CMS Experiment / Kevin Marcel Flöh ; Betreuer: T. Müller." Karlsruhe : KIT-Bibliothek, 2020. http://d-nb.info/1204132682/34.
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