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The Standard Model Higgs Boson Discovery Potential In The Decay Channel H Zzsuperscript 4mu With The Cms Detector
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Book Synopsis The Standard Model Higgs Boson Discovery Potential in the Decay Channel H --] ZZ[superscript*] --] 4[mu] with the CMS Detector by : Alexey Alexandrovich Drozdetskiy
Download or read book The Standard Model Higgs Boson Discovery Potential in the Decay Channel H --] ZZ[superscript*] --] 4[mu] with the CMS Detector written by Alexey Alexandrovich Drozdetskiy and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: The Compact Muon Solenoid (CMS) is a general purpose detector at the Large Hadron Collider (LHC) currently under construction at CERN with start-up date in 2008. The putative Higgs boson is the most plausible solution for the mystery of mass in the Standard Model of elementary particles and its discovery is one of the prime goals for the LHC. Higgs boson search. Our research presents an optimized strategy for a Higgs boson search in its four-muon decay channel, H--> ZZ[superscript*]--> 4[mu], also known as a golden decay channel. The method automatically ensures an optimal signal-to-background ratio for any mass, at which the Higgs boson might appear. The most important theoretical and instrumental systematic errors are taken into account and our search was conducted in a broad range of possible Higgs boson masses. Muon reconstruction. We developed an algorithm for a fast and efficient muon track segment reconstruction in Cathode Strip Chambers. Designed to be CPU-efficient, the algorithm is specifically targeted for High Level Trigger purposes. The segment-finding efficiency and the spatial resolution attainable with the proposed algorithm and the required CPU time were validated using the cosmic ray data taken by the CMS in 2006. The results of validation showed the efficiency and spatial resolution attainable with the algorithm are well within the High Level Trigger requirements and the algorithm's timing performance is by far superior to all algorithms previously used in CMS.
Book Synopsis Discovery of a Higgs Boson in the H to ZZ to 4 Leptons Channel by : Adish Pradeep Vartak
Download or read book Discovery of a Higgs Boson in the H to ZZ to 4 Leptons Channel written by Adish Pradeep Vartak and published by . This book was released on 2014 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for the standard model Higgs boson is presented using data collected in pp collisions at the LHC with the CMS detector. Two distinct Higgs boson decay channels are analyzed. The H --> ZZ --> 2l2[Nu] channel, where l = e or [mu], is analyzed with data collected in 2011 at sqrt(s) = 7 TeV corresponding to an integrated luminosity of 4.6 fb−1. No significant excess of events is observed above the background expectation and the presence of a standard model Higgs boson is excluded in the mass range 270-440 GeV at 95% confidence level. The H --> ZZ --> 4l channel is analyzed with data collected in 2011 and 2012 corresponding to integrated luminosities of 5.1 and 19.7 fb−1 at sqrt(s) = 7 and 8 TeV respectively. A new boson is observed with a local significance of 6.7 standard deviations. The mass of this particle is measured to be 125.6±0.4(stat)±0.2(syst) GeV, and it has a signal strength of 1.04+0.29/-0.25(stat) +0.14/-0.08(syst) relative to the standard model Higgs boson expectation. The width of this particle is measured to be less than 3.6 GeV at 95% confidence level. The spin and parity of this particle is found to be consistent with the standard model Higgs boson.
Book Synopsis Discovery and Measurement of the Higgs Boson in the WW Decay Channel by : David Hall
Download or read book Discovery and Measurement of the Higgs Boson in the WW Decay Channel written by David Hall and published by Springer. This book was released on 2015-06-15 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Search for tt̄H Production in the H → bb̅ Decay Channel by : Marcel Rieger
Download or read book Search for tt̄H Production in the H → bb̅ Decay Channel written by Marcel Rieger and published by Springer Nature. This book was released on 2021-02-25 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: In 1964, a mechanism explaining the origin of particle masses was proposed by Robert Brout, François Englert, and Peter W. Higgs. 48 years later, in 2012, the so-called Higgs boson was discovered in proton-proton collisions recorded by experiments at the LHC. Since then, its ability to interact with quarks remained experimentally unconfirmed. This book presents a search for Higgs bosons produced in association with top quarks tt̄H in data recorded with the CMS detector in 2016. It focuses on Higgs boson decays into bottom quarks H → bb̅ and top quark pair decays involving at least one lepton. In this analysis, a multiclass classification approach using deep learning techniques was applied for the first time. In light of the dominant background contribution from tt̄ production, the developed method proved to achieve superior sensitivity with respect to existing techniques. In combination with searches in different decay channels, the presented work contributed to the first observations of tt̄H production and H → bb̅ decays.
Book Synopsis Search for the Standard Model Higgs Boson in the H ZZ L + L - Qq Decay Channel at CMS by : Francesco Pandolfi
Download or read book Search for the Standard Model Higgs Boson in the H ZZ L + L - Qq Decay Channel at CMS written by Francesco Pandolfi and published by . This book was released on 2013-09-30 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Search for the Standard Model Higgs Boson in the Decay Channel Into Four Muons with the CMS Detector by : Matteo Sani
Download or read book Search for the Standard Model Higgs Boson in the Decay Channel Into Four Muons with the CMS Detector written by Matteo Sani and published by . This book was released on 2006 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Search for a Higgs Boson in the Decay Channel $H$ to ZZ(*) to $q$ Qbar $\ell-̂$ L+ in $pp$ Collisions at $\sqrt{s} by :
Download or read book Search for a Higgs Boson in the Decay Channel $H$ to ZZ(*) to $q$ Qbar $\ell-̂$ L+ in $pp$ Collisions at $\sqrt{s} written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for the standard model Higgs boson decaying into two Z bosons with subsequent decay into a final state containing two quark jets and two leptons, H to ZZ(*) to q q-bar l-l+ is presented. Results are based on data corresponding to an integrated luminosity of 4.6 inverse femtobarns of proton-proton collisions at sqrt(s)=7 TeV, collected with the CMS detector at the LHC. In order to discriminate between signal and background events, kinematic and topological quantities, including the angular spin correlations of the decay products, are employed. Events are further classified according to the probability of the jets to originate from quarks of light or heavy flavor or from gluons. No evidence for the Higgs boson is found, and upper limits on its production cross section are determined for a Higgs boson of mass between 130 and 600 GeV.
Book Synopsis Fishing for New Physics with Massive Neutral Dibosons by : Matthew Ervin Chasco
Download or read book Fishing for New Physics with Massive Neutral Dibosons written by Matthew Ervin Chasco and published by . This book was released on 2014 with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Standard Model of particle physics is a theory describing the fundamental interactions and properties of subatomic particles. A key feature is its ability to explain particle mass through the Higgs mechanism, and a by-product of this mechanism is the Higgs boson. The discovery of the Higgs boson, in 2012 at CERN, completed the Standard Model particle zoo, but observed phenomena, like dark matter, remain unexplained. The analyses presented explore proton-proton collison events resulting in a Z boson plus missing transverse energy (MET). The motivation for this is to investigate two processes: Standard Model (SM) ZZ production, and beyond Standard Model (BSM) ZH production, in particular the ZZ to 2l2nu and ZH to 2l + H(inv) channels. The place-holder H(inv) is for all Higgs boson decay modes resulting in undetected "invisible" particles, which may branch to new physics, like dark matter particles. The data used are from Run 1 (2011-2012) of CMS, where proton-proton collisions at 7 TeV and 8 TeV were delivered by the LHC. The Compact Muon Solenoid (CMS) is a general-purpose detector located along the Large Hadron Collider (LHC), which is a particle accelerator at CERN in Geneva, Switzerland. To extract these signals containing real MET from background containing fake mismeasured MET, a new "reduced MET" variable is constructed and optimized. This assists in the measurement of the ZZ production cross section. The results of the exclusive ZZ to 2l2nu cross section measurement are 201+82/-69 fb and 264+81/-64 fb from the 7 and 8 TeV portions of Run 1 data, respectively. Bayesian unfolding is used to measure a cross section of 224+68/-70 fb from the 8 TeV data. These results both agree with next-to-leading order predictions from the Standard Model. The differential cross section as a function of transverse momentum of the Z boson is also measured from unfolding, for the purpose of providing a way to compare data to new theories. To distinguish ZH to 2l + H(inv) from ZZ to 2l2nu a machine learning algorithm is used with physical variables as the input. A shape analysis is performed on the resulting distribution, and an upper limit is placed at 95% C.L. on the invisible branching fraction of the Higgs boson. For a Higgs boson with a Standard Model cross section and mass of 125 GeV, the observed limit on the branching fraction is 52% and the expected is 49%. Considering a mass spectrum of 115-200 GeV, a fully invisible Higgs is excluded for masses below 163 GeV.
Book Synopsis Detailed Studies of the CMS Potential to Measure the Standard Model Higgs Boson in the Gg -> H -> WW -> Lvlv Channel at LHC by : Giovanna Madlaina Davatz
Download or read book Detailed Studies of the CMS Potential to Measure the Standard Model Higgs Boson in the Gg -> H -> WW -> Lvlv Channel at LHC written by Giovanna Madlaina Davatz and published by . This book was released on 2007 with total page 165 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Discovery of the Higgs Boson, Measurements of Higgs Boson Properties, and Search for High Mass Beyond the Standard Model Scalar Particle in the Diphoton Final State with the ATLAS Detector at the Large Hadron Collider by : Hongtao Yang
Download or read book Discovery of the Higgs Boson, Measurements of Higgs Boson Properties, and Search for High Mass Beyond the Standard Model Scalar Particle in the Diphoton Final State with the ATLAS Detector at the Large Hadron Collider written by Hongtao Yang and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: With 4.8~$\rm{fb}^{-1}$ of proton-proton collision data collected at $\sqrt{s}=7~\rm{TeV}$ in 2011, and 5.9~$\rm{fb}^{-1}$ collected at $\sqrt{s}=8~\rm{TeV}$ in 2012 by the ATLAS detector at the Large Hadron Collider, an excess of 4.5 standard deviations from the background-only hypothesis is observed near 126.5~GeV in the diphoton invariant mass spectra. Along with the excesses observed in the $H \rightarrow ZZ^{(*)}\rightarrow \ell\ell\ell\ell$ and $H \rightarrow WW^{(*)}\rightarrow \ell\nu\ell\nu$ channels, the observation of a Higgs-like particle is established at 6.0 standard deviations level. With more data accumulated during LHC Run~1, the measurements of Higgs boson couplings and mass in the $H\to\gamma\gamma$ channel are conducted by the ATLAS experiment based on 4.5~$\rm{fb}^{-1}$ of proton-proton collisions at $\sqrt{s}=7~\rm{TeV}$ collected in 2011, and 20.3~$\rm{fb}^{-1}$ at $\sqrt{s}=8~\rm{TeV}$ collected in 2012. The combined signal strength, defined as number of observed Higgs boson decays to diphoton divided by the corresponding Standard Model prediction, is measured to be $1.17 \ ^{+0.28}_{-0.26}$ assuming the Higgs boson mass being 125.4~$\rm{GeV}$. The signal strengths for individual Higgs boson production processes are also measured, and are found to be in good consistency with the Standard Model. The mass of the Higgs boson is measured in $H\to\gamma\gamma$ channel by the ATLAS experiment to be $125.98 \pm 0.50$~\GeV. This measurement is combined with the ones from ATLAS $H \rightarrow ZZ^{(*)}\rightarrow \ell\ell\ell\ell$ as well as CMS $H\to\gamma\gamma$ and $H \rightarrow ZZ^{(*)}\rightarrow \ell\ell\ell\ell$. The Higgs boson mass measured from the combination is $125.09\pm0.24~\rm{GeV}$. With LHC center-of-mass energy increased to 13~TeV, a search for high mass Beyond the Standard Model scalar resonance is performed in the diphoton decay channel based on 15.4~$\rm{fb}^{-1}$ of proton-proton collision data collected by the ATLAS detector during 2015 and 2016. While a notable wide excess was first observed in the diphoton invariant mass spectrum from the 2015 data (3.2~$\rm{fb}^{-1}$) with mass near 750~GeV, it is not confirmed by the 2016 data with much higher statistics (12.4~$\rm{fb}^{-1}$). Limits on the production cross section times branching ratio of such resonances are set.
Book Synopsis Discovery of the Higgs Boson and a Search for Beyond the Standard Model Physics in ZZ Decays Using the CMS Detector at the LHC by :
Download or read book Discovery of the Higgs Boson and a Search for Beyond the Standard Model Physics in ZZ Decays Using the CMS Detector at the LHC written by and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A study of the pp to ZZ 6́2 llll final state is conducted using 19.6 inverse femtobarn of 8 TeV proton-proton collisions at the LHC using the CMS detector. The Standard Model pp 6́2 ZZ production cross section is measured to be 7.7+0.5 -0.5 (stat.) +0.6 -0.5(sys.) ± 0.3(lumi) pb. Evidence of a new Higgs-like boson is observed with a significance of 6.1ï3 at 126 GeV. 95% confidence level upper limits are set on the neutral anomalous triple gauge couplings; -0.004
Book Synopsis Observation of Standard Model Higgs Boson Decays to Tau Leptons and a Search for Dark Matter with the CMS Detector at the LHC by : Laura Margaret Dodd
Download or read book Observation of Standard Model Higgs Boson Decays to Tau Leptons and a Search for Dark Matter with the CMS Detector at the LHC written by Laura Margaret Dodd and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for the standard model (SM) Higgs boson which decays to a pair of [tau] leptons is presented in this thesis using 35.9 f b−1 of 13 TeV data collected in 2016 by the CMS detector at CERN. The final states considered require that (1) one [tau] lepton decays leptonically while the other decays hadronically ([mu][tau]h or e[tau]h), (2) both taus decay hadronically ([tau]h[tau]h) or (3) one tau lepton decays to an electron while the other decays to a muon (e[mu]). This thesis specifically focuses on the details of the semi-hadronic decay channels ([mu][tau]h and e[tau]h), and presents the results of all channels combined. The signal strength, [mu], relative to the expectation for the SM Higgs boson is measured to be [mu] = 1.09+0.27−0.24. An excess is observed (expected) corresponding to 4.9 (4.7) [sigma] using 2016 data. The observed (expected) significance reaches 5.9 (5.9) [sigma] when combined with 7 and 8 TeV data collected at CMS. Subsequently following the SM search, a search for dark matter (DM) is presented and interpreted in two simplified Higgs-portal models: a baryonic dark matter model and a two Higgs-doublet model. In this thesis, the Higgs boson is required to decay to an opposite- sign tau pair. The tau pair final states considered are e[tau]h, [mu][tau]h, and [tau]h[tau]h. The expected 95% confidence level upper limits are produced and compared with the observed limit. No significant deviations beyond the SM prediction are observed.
Book Synopsis Search for the Standard Model Higgs Boson in the Fully Leptonic WW Decay Channel at CMS by : Matthew LeBourgeois
Download or read book Search for the Standard Model Higgs Boson in the Fully Leptonic WW Decay Channel at CMS written by Matthew LeBourgeois and published by . This book was released on 2012 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for the Standard Model Higgs boson decaying to WW− is presented. Data is taken from pp collisions with center of mass energy sqrt(s) = 7 TeV at the LHC using the CMS detector over the course of 2011. The sum of the data collected amounts to an integrated luminosity of 4.6 fb−. Identification of WW− candidates is performed by searching for leptonic decays of both W bosons. The resulting signature is two oppositely charged leptons, electrons or muons, plus significant missing transverse energy in the final state. The other Standard Model processes which only serve as background to the Higgs boson search are removed via a series of selections aimed to reduce the backgrounds while keeping the highest possible signal-to-background ratio. The Higgs boson signal is identified over the non-resonant W+W− production by exploiting the spin correlation of the H [right arrow] WW decays. Details concerning the analysis selection criteria, the data-driven estimates of the major background processes and the systematic uncertainties of the analysis are all presented in detail. As no significant excess of events are observed above the Standard Model background estimates, upper limits are set on the Higgs boson production with respect to the Standard Model prediction. Exclusion of the Higgs boson is extended with respect to previous measurements to a range of 132-238 GeV with a 95% confidence level.
Book Synopsis Evidence for the Production of the Standard Model Higgs Boson Produced Via Vector Boson Fusion in the WW* Channel at the ATLAS Detector by : Koos van Nieuwkoop
Download or read book 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 published by . This book was released on 2017 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Search for the Standard Model Higgs Boson Decaying to a Bottom Quark Pair with the CMS Detector by : Matthew I. Fisher
Download or read book Search for the Standard Model Higgs Boson Decaying to a Bottom Quark Pair with the CMS Detector written by Matthew I. Fisher and published by . This book was released on 2014 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for the standard model Higgs boson is shown in the associated production channel with a Z boson and decay to bottom quarks. The data for this search was gathered from April 2011 until December 2012. The dataset corresponds to 5.0 fb ... 1 of pp collisions at p s = 7 TeV and 19.04 fb ... 1 of pp collisions at p s = 8 TeV . An excess of events is observed above the expected background with a local significance of 2.1 standard deviations, which is consistent with the expectation from the production of the standard model Higgs boson.
Book Synopsis Search for Exotic Higgs Boson Decays to Merged Diphotons by : Michael Andrews
Download or read book Search for Exotic Higgs Boson Decays to Merged Diphotons written by Michael Andrews and published by Springer Nature. This book was released on 2023-03-02 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes the first application at CMS of deep learning algorithms trained directly on low-level, “raw” detector data, or so-called end-to-end physics reconstruction. Growing interest in searches for exotic new physics in the CMS collaboration at the Large Hadron Collider at CERN has highlighted the need for a new generation of particle reconstruction algorithms. For many exotic physics searches, sensitivity is constrained not by the ability to extract information from particle-level data but by inefficiencies in the reconstruction of the particle-level quantities themselves. The technique achieves a breakthrough in the reconstruction of highly merged photon pairs that are completely unresolved in the CMS detector. This newfound ability is used to perform the first direct search for exotic Higgs boson decays to a pair of hypothetical light scalar particles H→aa, each subsequently decaying to a pair of highly merged photons a→yy, an analysis once thought impossible to perform. The book concludes with an outlook on potential new exotic searches made accessible by this new reconstruction paradigm.
Book Synopsis Discovery potential of heavy Standard Model Higgs boson through the H [fletxa cap a la dreta] ZZ [fletxa cap a la dreta] llvv channel at the LHC with the ATLAS detector by : Hugo Ruiz Pérez
Download or read book Discovery potential of heavy Standard Model Higgs boson through the H [fletxa cap a la dreta] ZZ [fletxa cap a la dreta] llvv channel at the LHC with the ATLAS detector written by Hugo Ruiz Pérez and published by . This book was released on 1998 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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