Search For New Resonances Decaying Via Wz To Leptons In Proton U2013 Proton Collisions At Sqrt S
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The Composite Nambu Goldstone Higgs
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Author : Giuliano Panico
language : en
Publisher: Springer
Release Date : 2015-11-17
The Composite Nambu Goldstone Higgs written by Giuliano Panico and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-11-17 with Science categories.
The Hierarchy Problem is arguably the most important guiding principle concerning the extension to high-energy scales of the Standard Model (SM) of Fundamental Interactions. Every scenario for addressing this issue unavoidably predicts new physics in the TeV energy range, which is currently being probed directly by the LHC experimental program. Among the possible solutions to the Hierarchy Problem, the scenario of a composite Higgs boson is a very simple idea and a rather plausible picture has emerged over the years by combining the following ingredients: First, the Higgs must be a (pseudo-) Nambu-Goldstone boson, rather than a generic hadron of the new strong sector. Second, through the so-called ‘partial compositeness’, SM particles mix with strong sector resonances with suitable quantum numbers, so that they become a linear combination of elementary and composite degrees of freedom. Recently, general descriptions of the Composite Higgs Scenario were developed which successfully capture the relevant features of this theoretical framework in a largely model-independent way. The present book provides a concise and illustrative introduction to the subject for a broad audience of graduate students and non-specialist researchers in the fields of particle, nuclear and gravitational physics.
Search For New Resonances Decaying Via Wz To Leptons In Proton U2013 Proton Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2014
Search For New Resonances Decaying Via Wz To Leptons In Proton U2013 Proton Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
A search is performed in proton–proton collisions at √s=8 TeV for exotic particles decaying via WZ to fully leptonic final states with electrons, muons, and neutrinos. The data set corresponds to an integrated luminosity of 19.5 fb-1. No significant excess is observed above the expected standard model background. Upper bounds at 95% confidence level are set on the production cross section of a W' boson as predicted by an extended gauge model, and on the W'WZ coupling. The expected and observed mass limits for a W' boson, as predicted by this model, are 1.55 and 1.47 TeV, respectively. Stringent limits are also set in the context of low-scale technicolor models under a range of assumptions for the model parameters.
A Search For T Overline T Resonances Using Lepton Plus Jets Events In Proton Proton Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2015
A Search For T Overline T Resonances Using Lepton Plus Jets Events In Proton Proton Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
A search for new particles that decay into top quark pairs is reported. The search is performed with the ATLAS experiment at the LHC using an integrated luminosity of 20.3 fb-1 of proton-proton collision data collected at a centre-of-mass energy of \(\sqrt{s}=8 \) TeV. The lepton-plus-jets final state is used, where the top pair decays to \({W}^{+}b{W}^{-}\overline{b} \), with one W boson decaying leptonically and the other hadronically. The invariant mass spectrum of top quark pairs is examined for local excesses or deficits that are inconsistent with the Standard Model predictions. No evidence for a top quark pair resonance is found, and 95% confidence-level limits on the production rate are determined for massive states in benchmark models. The upper limits on the cross-section times branching ratio of a narrow Z' boson decaying to top pairs range from 4.2 pb to 0.03 pb for resonance masses from 0.4 TeV to 3.0 TeV. A narrow leptophobic topcolour Z' boson with mass below 1.8 TeV is excluded. Upper limits are set on the cross-section times branching ratio for a broad colour-octet resonance with [Gamma]/m = 15% decaying to \(t\overline{t} \). These range from 4.8 pb to 0.03 pb for masses from 0.4 TeV to 3.0 TeV. A Kaluza-Klein excitation of the gluon in a Randall-Sundrum model is excluded for masses below 2.2 TeV.
Search For Heavy Resonances Decaying To Tau Lepton Pairs In Proton Proton Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2016
Search For Heavy Resonances Decaying To Tau Lepton Pairs In Proton Proton Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
A search for heavy resonances that decay to tau lepton pairs is performed using proton-proton collisions at \sqrt{s}$ = 13 TeV. The data were collected with the CMS detector at the CERN LHC and correspond to an integrated luminosity of 2.2 inverse femtobarns. The observations are in agreement with standard model predictions. An upper limit at 95% confidence level on the product of the production cross section and branching fraction into tau lepton pairs is calculated as a function of the resonance mass. For the sequential standard model, the presence of Z' bosons decaying into tau lepton pairs is excluded for Z' masses below 2.1 TeV, extending previous limits for this final state. For the topcolor-assisted technicolor model, which predicts Z' bosons that preferentially couple to third-generation fermions, Z' masses below 1.7 TeV are excluded, representing the most stringent limit to date.
Search For Leptophobic Z Bosons Decaying Into Four Lepton Final States In Proton Proton Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2017
Search For Leptophobic Z Bosons Decaying Into Four Lepton Final States In Proton Proton Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
A search for heavy narrow resonances decaying into four-lepton final states from cascade decays of a Z' boson has been performed using proton-proton collision data at sqrt(s) = 8 TeV collected by the CMS experiment, corresponding to an integrated luminosity of 19.7 inverse femtobarns. No excess of events over the standard model background expectation is observed. Upper limits for a benchmark model on the product of cross section and branching fraction for the production of these heavy narrow resonances are presented. The limit excludes leptophobic Z' bosons with masses below 2.5 TeV within the benchmark model. This is the first result to constrain a leptophobic Z' resonance in the four-lepton channel.
Search For Displaced Leptons In Proton Proton Collisions At Sqare Root S
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Author : Bryan Cardwell
language : en
Publisher:
Release Date : 2021
Search For Displaced Leptons In Proton Proton Collisions At Sqare Root S written by Bryan Cardwell and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021 with Leptons (Nuclear physics) categories.
A search is presented for new long-lived particles that propagate a measurable distance through the CMS detector before decaying to leptons. The search is performed in 113–118 fb-1 of proton-proton collision data produced by the CERN LHC at a center-of-mass energy of 13 TeV and collected by the CMS detector in 2016, 2017, and 2018. Events are selected with two leptons (an electron and a muon, two electrons, or two muons) that both have transverse impact parameter values between 0.01 and 10 cm. Using transverse impact parameter as the discriminating variable allows for sensitivity to displaced decays without requiring that the leptons form a common vertex. The search is designed to be sensitive to a wide range of new physics models that produce displaced di-lepton final states. The observation is consistent with the background-only hypothesis, and limits are set on the product of the cross-section of top squark pair production and the branching fraction to a lepton and a b or d quark through an R-parity-violating vertex. For a proper decay length hypothesis of 2 cm, top squarks with masses up 1500 GeV are excluded at the 95% confidence level.
Search For Narrow High Mass Resonances In Proton U2013 Proton Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2015
Search For Narrow High Mass Resonances In Proton U2013 Proton Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
A search for a narrow, high-mass resonance decaying into Z and Higgs (H) bosons is presented. The final state studied consists of a merged jet pair and a ? pair resulting from the decays of Z and H bosons, respectively. This analysis is based on a data sample of proton–proton collisions at a center-ofmass energy of 8 TeV, collected with the CMS experiment in 2012, and corresponding to an integrated luminosity of 19.7 fb-1. In the resonance mass range of interest, which extends from 0.8 to 2.5 TeV, the Z and H bosons are produced with large momenta, which implies that the final products of the two quarks or the two ? leptons must be detected within a small angular interval. A combination of all possible decay modes of the ? leptons, production cross sections in a range between 0.9 and 27.8 fb are excluded at 95% confidence level, depending on the resonance mass.
Search For Heavy Resonance Decays Into Top Quark Pairs Using A Lepton Plus Jets Final State In Proton Proton Collisions At S
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Author : Kyle Krowpman
language : en
Publisher:
Release Date : 2022
Search For Heavy Resonance Decays Into Top Quark Pairs Using A Lepton Plus Jets Final State In Proton Proton Collisions At S written by Kyle Krowpman and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022 with Electronic dissertations categories.
This thesis presents two studies in a search for new heavy resonances with 139 fb-1 of proton-proton collisions delivered by the Large Hadron Collider at √s = 13 TeV as measured by the ATLAS detector. In many Standard Model extensions, the top quark plays an important role in the dynamics of electroweak symmetry breaking, and so the studies presented here focus on heavy resonance searches in the top-antitop decay channel and their combination with searches for heavy resonances decaying into other final states. The first study detailed in this thesis is a search for new heavy resonances in a semileptonically decaying top-antitop final state where no significant excesses of data were observed with respect to the background prediction. That being so, exclusion limits at the 95% confidence level were placed on possible resonant masses for a Z′ in a leptophobic topcolor-assisted technicolor model and for a bulk Randall-Sundrum graviton at 4.2 TeV and 1.0 TeV, respectively. This top-antitop search was combined with searches in orthogonal final states performed by the ATLAS Collaboration from which limit contours were placed at the 95% confidence level in the space of couplings to Standard Model particles for the Heavy Vector Triplet model.
Search For New Heavy Resonances Decaying To T T Pairs At The Lhc With Square Root S
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Author : Indara Suarez
language : en
Publisher:
Release Date : 2015
Search For New Heavy Resonances Decaying To T T Pairs At The Lhc With Square Root S written by Indara Suarez and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
The Standard Model (SM) describes the known fundamental particles and their interactions due to the electromagnetic, weak, and strong forces through vector boson exchange. Although the SM has had major success in predicting a wealth of experimental measurements, astrophysical evidence for dark matter the observation of neutrino oscillations, and the matter-antimatter asymmetry in the universe indicate that the SM is not a complete theory. In addition to these experimental observations, problems stemming from the failure to incorporate the gravitational force and the quantum instability of the mass of the Higgs Boson have also contributed to the motivation to search for physics beyond the SM. Multiple theoretical scenarios, including those inspired by Grand Unified Theories (GUTs), models with extra spatial dimensions, and Supersymmetry (SUSY), have been proposed to address the shortcomings of the SM. In many of these models, the new symmetries that extend the SM gauge structure require the existence of new heavy neutral gauge bosons. Regardless of the exact nature or production mechanism of the hypothesized heavy bosons, they may be observed by studying dilepton final states at high energy colliders. As many models of physics beyond the SM predict enhanced couplings to third generation particles, searches for the new heavy bosons decaying into two T-leptons are particularly well motivated. We present a direct search for high mass neutral resonances decaying into two opposite sign T-leptons using data from proton-proton collisions at the LHC with center-of-mass energy [square root of] s = 7 TeV. The search has been conducted using data recorded by the Compact Muon Solenoid (CMS) experiment, corresponding to an integrated luminosity of 4.94 fb-1 and includes final states with leptonic and hadronic decays of the T-lepton. The data has been found to be consistent with the background-only hypothesis within the sensitivity of the measurement. Using the Sequential Standard Model Z'-boson as a benchmark, we set a 95% confidence-level upper limit on the mass of Z'-bosons decaying to pairs of T-leptons. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/154969
Search For Massive Resonances Decaying Into Pairs Of Boosted Bosons In Semi Leptonic Final States At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2014
Search For Massive Resonances Decaying Into Pairs Of Boosted Bosons In Semi Leptonic Final States At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
Our search for new resonances decaying to WW, ZZ, or WZ is presented. Final states are considered in which one of the vector bosons decays leptonically and the other hadronically. Results are based on data corresponding to an integrated luminosity of 19.7 fb-1 recorded in proton-proton collisions at √s = 8 TeV with the CMS detector at the CERN LHC. Techniques aiming at identifying jet substructures are used to analyze signal events in which the hadronization products from the decay of highly boosted W or Z bosons are contained within a single reconstructed jet. Upper limits on the production of generic WW, ZZ, or WZ resonances are set as a function of the resonance mass and width. We also increase the sensitivity of the analysis by statistically combining the results of this search with a complementary study of the all-hadronic final state. Upper limits at 95% confidence level are set on the bulk graviton production cross section in the range from 700 to 10 fb for resonance masses between 600 and 2500 GeV, respectively. These limits on the bulk graviton model are the most stringent to date in the diboson final state.