Download or read book Measurement of W Bb and a Search for MSSM Higgs Bosons with the CMS Detector at the LHC written by and published by . This book was released on 2014 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes a Standard Model (SM) cross section measurement of W+bb as well as a search for neutral Higgs bosons in the Minimal Supersymmetric Extension of the Standard Model (MSSM) decaying to tau pairs. The measurement of W+bb was performed using proton-proton collisions at sqrt(s) = 7 TeV in a data sample collected with the CMS experiment at the LHC corresponding to an integrated luminosity of 5.0 1/fb. The W+bb events are selected in the W to muon + neutrino decay mode by requiring a muon with transverse momentum pT>25 GeV and pseudorapidity absolute eta less than 2.1, and exactly two b-tagged jets with pT>25 GeV and absolute eta less than 2.4. The measured W+bb production cross section in the fiducial region, calculated at the level of final-state particles, is 0.53± 0.05(stat.) ± 0.09 (syst.) ± 0.06 (theory) ± 0.01 (lum.) pb, in agreement with the SM prediction. This measurement is a sensitive test of heavy quark production calculated with perturbative QCD. It also serves as an important benchmark in new physics searches which include a single isolated lepton and one or more b jets in the final state, as W+bb becomes an irreducible background. Also presented is a search for the CP-even MSSM Higgs bosons, H and h, and the CP-odd MSSM pseudoscalar, A, in their decays to tau pairs. This search is performed using events recorded by the CMS experiment at the LHC in 2011 and 2012 at a center-of-mass energy of 7 TeV and 8 TeV respectively. The dataset corresponds to an integrated luminosity of 24.6 1/fb, with 4.9 1/fb at 7 TeV and 19.7 1/fb at 8 TeV. To enhance the sensitivity to neutral MSSM Higgs bosons, the search includes the case where the Higgs boson is produced in association with a b-quark jet. No excess is observed in the tau-pair invariant-mass spectrum.

Download or read book Search for Higgs Boson Pair Production in the bb Decay Channel written by Luca Cadamuro and published by Springer. This book was released on 2018-12-06 with total page 273 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents innovative contributions to the CMS experiment in the new trigger system for the restart of the LHC collisions in Run II, as well as original analysis methods and important results that led to official publications of the Collaboration. The author's novel reconstruction algorithms, deployed on the Field-Programmable Gate Arrays of the new CMS trigger architecture, have brought a gain of over a factor 2 in efficiency for the identification of tau leptons, with a very significant impact on important H boson measurements, such as its decays to tau lepton pairs and the search for H boson pair production. He also describes a novel analysis of HH → bb tautau, a high priority physics topic in a difficult channel. The original strategy, optimisation of event categories, and the control of the background have made the result one of the most sensitive concerning the self-coupling of the Higgs boson among all possible channels at the LHC.

Download or read book Search for the Higgs Boson Produced in Association with Top Quarks with the CMS Detector at the LHC written by Cristina Martin Perez and published by Springer Nature. This book was released on 2022-02-09 with total page 291 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work, the interaction between the Higgs boson and the top quark is studied with the proton-proton collisions at 13 TeV provided by the LHC at the CMS detector at CERN (Geneva). At the LHC, these particles are produced simultaneously via the associate production of the Higgs boson with one top quark (tH process) or two top quarks (ttH process). Compared to many other possible outcomes of the proton-proton interactions, these processes are very rare, as the top quark and the Higgs boson are the heaviest elementary particles known. Hence, identifying them constitutes a significant experimental challenge. A high particle selection efficiency in the CMS detector is therefore crucial. At the core of this selection stands the Level-1 (L1) trigger system, a system that filters collision events to retain only those with potential interest for physics analysis. The selection of hadronically decaying τ leptons, expected from the Higgs boson decays, is especially demanding due to the large background arising from the QCD interactions. The first part of this thesis presents the optimization of the L1 τ algorithm in Run 2 (2016-2018) and Run 3 (2022-2024) of the LHC. It includes the development of a novel trigger concept for the High-Luminosity LHC, foreseen to start in 2027 and to deliver 5 times the current instantaneous luminosity. To this end, sophisticated algorithms based on machine learning approaches are used, facilitated by the increasingly modern technology and powerful computation of the trigger system. The second part of the work presents the search of the tH and ttH processes with the subsequent decays of the Higgs boson to pairs of τ lepton, W bosons or Z bosons, making use of the data recorded during Run 2. The presence of multiple particles in the final state, along with the low cross section of the processes, makes the search an ideal use case for multivariant discriminants that enhance the selectivity of the signals and reject the overwhelming background contributions. The discriminants presented are built using state-of-the-art machine learning techniques, able to capture the correlations amongst the processes involved, as well as the so-called Matrix Element Method (MEM), which combines the theoretical description of the processes with the detector resolution effects. The level of sophistication of the methods used, along with the unprecedented amount of collision data analyzed, result in the most stringent measurements of the tH and ttH cross sections up to date.

Download or read book A Search for Charged Higgs Bosons in Multilepton Final States and a Measurement of p p to WZ to l v l l with the CMS Detector at the LHC written by Devin Nathaniel Taylor and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a search for a doubly-charged Higgs boson in three and four lepton final states. The two production modes considered are the associated production mode with a doubly-charged Higgs boson produced in association with a singly-charged Higgs boson and the pair production mode with the simultaneous production of two doubly-charged Higgs bosons. The search is performed with 12.9 fb-1 of square root s = 13 TeV proton-proton collision data collected with the Compact Muon Solenoid at the Large Hadron Collider. In addition, this thesis presents the first measurement of the WZ production cross section in proton-proton collisions at square root s = 13 TeV. The measurement is performed in the WZ to [l][v][l]'[l]' decay mode where [l], [l]' = e, [mu] with an integrated luminosity of 2.3 fb-1.

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.

Download or read book Search for the Higgs Boson in the Vector Boson Fusion Channel at the ATLAS Detector written by Eric Ouellette and published by Springer. This book was released on 2015-01-20 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Observation of a New State in the Search for the Higgs Boson at CMS written by Giovanni Petrucciani and published by Springer. This book was released on 2014-12-04 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes the searches that lead to the discovery of a Higgs boson performed at CMS, one of the two main experiments at the CERN LHC. After an overview of the theory and of the CMS experiment, all search channels are described, with emphasis on the ones with the best sensitivity. The statistical methodology used to analyse and the outcomes of the searches and the discovery results are then presented in detail.

Download or read book Precision Measurement of the Higgs Boson Mass and Search for Dilepton Mass Resonances in H to 4l Decays Using the CMS Detector at the LHC written by Jake Rosenzweig and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Expectations of the total uncertainty are placed on the Higgs boson mass (mH) in the H to ZZstar to 4l (l = e, mu) decay channel. The value of mH, including statistical and systematic uncertainties, is estimated to be mH = 125.38 +- 0.11 [0.11 (stat.) +- 0.02 (syst.)] GeV. Once the data are unblinded, this measurement is predicted to be the world's most precise measurement of mH to date. The data used in the analysis were produced by proton-proton collisions at the Large Hadron Collider (LHC) with a center-of-mass energy of 13 TeV during Run 2 (2016-2018), corresponding to an integrated luminosity of 137.1 fb-1, and were collected by the Compact Muon Solenoid experiment. Using data sets from the same LHC run period, a search for low-mass dilepton resonances in Higgs boson decays to the 4l final state is also conducted. The Hidden Abelian Higgs Model is used in the search for a beyond the Standard Model dark photon (ZD) particle. Constraints are placed at 95% confidence level on the Higgs-mixing parameter k

Download or read book Measurement of the Jet Momentum Resolution and Search for a Light Standard Model Higgs Boson in the H bb W lv Channel with the CMS Detector at the LHC written by Hauke Held and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Phenomena Beyond the Standard Model What Do We Expect for New Physics to Look Like written by Roman Pasechnik and published by Frontiers Media SA. This book was released on 2020-09-03 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contact.

Download or read book Response of the High Granularity Calorimeter HGCAL and Characterisation of the Higgs Boson written by Matteo Bonanomi and published by Springer Nature. This book was released on 2023-05-23 with total page 281 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book highlights the most complete characterization of the Higgs boson properties performed to date in the "golden channel," i.e., decay into a pair of Z bosons which subsequently decay into four leptons. The data collected by the CMS experiment in the so-called Run-II data-taking period of the LHC are used to produce an extensive set of results that test in detail the predictions of the Standard Model. Given the remarkable predictive power of the SM when including the Higgs boson, possible new physics will require even more extensive studies at higher statistics. A massive upgrade of the detectors is necessary to maintain the current physics performance in the harsh environment of the High-Luminosity LHC (HL-LHC) project, expected to start by the end of 2027. The CMS Collaboration will replace the current endcap calorimeters with a High Granularity Calorimeter (HGCAL). The HGCAL will be the very first large-scale silicon-based imaging calorimeter ever employed in a high-energy physics experiment. This book presents the results of the analysis of the test beam data collected with the first large-scale prototype of the HGCAL. The results of this analysis are used to corroborate the final design of the HGCAL and its nominal physics performance expected for the HL-LHC operations.

Download or read book Measurement of W W Production and Search for the Higgs Boson in Pp Collisions at Sqrt s written by and published by . This book was released on 2011 with total page 47 pages. Available in PDF, EPUB and Kindle. Book excerpt: A measurement of WW production in pp collisions at sqrt(s) = 7 TeV and a search for the Higgs boson are reported. The WW candidates are selected in events with two leptons, either electrons or muons. The measurement is performed using LHC data recorded with the CMS detector, corresponding to an integrated luminosity of 36 inverse picobarns. The pp to WW cross section is measured to be 41.1 +/- 15.3 (stat) +/- 5.8 (syst) +/- 4.5 (lumi) pb, consistent with the standard model prediction. Limits on WW gamma and WWZ anomalous triple gauge couplings are set. The search for the standard model Higgs boson in the WW decay mode does not reveal any evidence of excess above backgrounds. Limits are set on the production of the Higgs boson in the context of the standard model and in the presence of a sequential fourth family of fermions with high masses. In the latter context, a Higgs boson with mass between 144 and 207 GeV is ruled out at 95% confidence level.

Download or read book Search for the MSSM Neutral Higgs Bosons with the CMS Experiment at LHC written by Gianni Masetti and published by . This book was released on 2005 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measurement of Higgs Boson Production and Properties in the WW Decay Channel with Leptonic Final States written by and published by . This book was released on 2014 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for the standard model Higgs boson decaying to a W-boson pair at the LHC is reported. The event sample corresponds to an integrated luminosity of 4.9 and 19.4 inverse femtobarns collected with the CMS detector in pp collisions at √s = 7 and 8 TeV, respectively. The Higgs boson candidates are selected in events with two or three charged leptons. An excess of events above background is observed, consistent with the expectation from the standard model Higgs boson with a mass of around 125 GeV. The probability to observe an excess equal or larger than the one seen, under the background-only hypothesis, corresponds to a significance of 4.3 standard deviations for mH = 125.6 GeV. The observed signal cross section times the branching fraction to WW for mH = 125.6 GeV is 0.72+0.20-0.18 times the standard model expectation. The spin-parity JP=0+ hypothesis is favored against a narrow resonance with JP=2+ or JP=0- that decays to a W-boson pair. Lastly, this result provides strong evidence for a Higgs-like boson decaying to a W-boson pair.

Download or read book Search for the SM Higgs Boson in the W Z H Channel with H Bb Using the ATLAS Detector at the LHC written by Garoé González Parra and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Search for Neutral MSSM Higgs Bosons Decaying to mu mu in Pp Collisions at sqrt s written by and published by . This book was released on 2015 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for neutral Higgs bosons predicted in the minimal supersymmetric standard model (MSSM) for [mu]+[mu]- decay channels is presented. Our analysis uses data collected by the CMS experiment at the LHC in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV, corresponding to integrated luminosities of 5.1 and 19.3 fb-1, respectively. The search is sensitive to Higgs bosons produced either through the gluon fusion process or in association with a bb quark pair. No statistically significant excess is observed in the [mu]+[mu]- mass spectrum. Results are interpreted in the framework of several benchmark scenarios, and the data are used to set an upper limit on the MSSM parameter tan [beta] as a function of the mass of the pseudoscalar A boson in the range from 115 to 300 GeV. Furthermore, the model independent upper limits are given for the product of the cross section and branching fraction for gluon fusion and b quark associated production at √s = 8 TeV. As a result, they are the most stringent limits obtained to date in this channel.

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