Search for Heavy Lepton Resonances Decaying to a Z Boson and a Lepton in Pp Collisions at \(\sqrt{s}

Search for Heavy Lepton Resonances Decaying to a Z Boson and a Lepton in Pp Collisions at \(\sqrt{s} PDF Author:
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Languages : en
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Book Description
A search for heavy leptons decaying to a Z boson and an electron or a muon is presented. The search is based on pp collision data taken at \(\sqrt{s}=8 \) TeV by the ATLAS experiment at the CERN Large Hadron Collider, corresponding to an integrated luminosity of 20.3 fb−1. Three high-transverse-momentum electrons or muons are selected, with two of them required to be consistent with originating from a Z boson decay. No significant excess above Standard Model background predictions is observed, and 95% confidence level limits on the production cross section of high-mass trilepton resonances are derived. The results are interpreted in the context of vector-like lepton and type-III seesaw models. For the vector-like lepton model, most heavy lepton mass values in the range 114-176 GeV are excluded. For the type-III seesaw model, most mass values in the range 100-468 GeV are excluded.

Search for Heavy Lepton Resonances Decaying to a Z Boson and a Lepton in Pp Collisions at \(\sqrt{s}

Search for Heavy Lepton Resonances Decaying to a Z Boson and a Lepton in Pp Collisions at \(\sqrt{s} PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
A search for heavy leptons decaying to a Z boson and an electron or a muon is presented. The search is based on pp collision data taken at \(\sqrt{s}=8 \) TeV by the ATLAS experiment at the CERN Large Hadron Collider, corresponding to an integrated luminosity of 20.3 fb−1. Three high-transverse-momentum electrons or muons are selected, with two of them required to be consistent with originating from a Z boson decay. No significant excess above Standard Model background predictions is observed, and 95% confidence level limits on the production cross section of high-mass trilepton resonances are derived. The results are interpreted in the context of vector-like lepton and type-III seesaw models. For the vector-like lepton model, most heavy lepton mass values in the range 114-176 GeV are excluded. For the type-III seesaw model, most mass values in the range 100-468 GeV are excluded.

Search for Heavy Lepton Resonances Decaying to a Z Boson and a Lepton in Pp Collisions at {u221A}s

Search for Heavy Lepton Resonances Decaying to a Z Boson and a Lepton in Pp Collisions at {u221A}s PDF Author:
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Languages : en
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Book Description
In this study, a search for heavy leptons decaying to a Z boson and an electron or a muon is presented. The search is based on pp collision data taken at √s=8 TeV by the ATLAS experiment at the CERN Large Hadron Collider, corresponding to an integrated luminosity of 20.3 fb−1. Three high-transverse-momentum electrons or muons are selected, with two of them required to be consistent with originating from a Z boson decay. No significant excess above Standard Model background predictions is observed, and 95% confidence level limits on the production cross section of high-mass trilepton resonances are derived. The results are interpreted in the context of vector-like lepton and type-III seesaw models. For the vector-like lepton model, most heavy lepton mass values in the range 114–176 GeV are excluded. For the type-III seesaw model, most mass values in the range 100–468 GeV are excluded.

Search for Heavy Lepton Resonances Decaying to a Z Boson and a Lepton in Proton-proton at [radical]s

Search for Heavy Lepton Resonances Decaying to a Z Boson and a Lepton in Proton-proton at [radical]s PDF Author: Liv Wiik-Fuchs
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Languages : en
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Search for Leptophobic Z' Bosons Decaying Into Four-lepton Final States in Proton-proton Collisions at Sqrt(s)

Search for Leptophobic Z' Bosons Decaying Into Four-lepton Final States in Proton-proton Collisions at Sqrt(s) PDF Author:
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Languages : en
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Book Description
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 Heavy Resonances Decaying to Tau Lepton Pairs in Proton-proton Collisions at $\sqrt{s}$

Search for Heavy Resonances Decaying to Tau Lepton Pairs in Proton-proton Collisions at $\sqrt{s}$ PDF Author:
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Languages : en
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Book Description
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 a Heavy Gauge Boson Decaying to a Charged Lepton and a Neutrino in 1 Fb-1 of pp Collisions at {u221A}s

Search for a Heavy Gauge Boson Decaying to a Charged Lepton and a Neutrino in 1 Fb-1 of pp Collisions at {u221A}s PDF Author:
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Category :
Languages : en
Pages : 19

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Book Description
The ATLAS detector at the LHC is used to search for heavy charged gauge bosons (W'), decaying to a charged lepton (electron or muon) and a neutrino. Results are presented based on the analysis of pp collisions at a center-of-mass energy of 7 TeV corresponding to an integrated luminosity of 1.04 fb−1. No excess beyond Standard Model expectations is observed. A W' with Sequential Standard Model couplings is excluded at the 95% confidence level for masses up to 2.15 TeV.

Search for a Heavy Gauge Boson Decaying to a Charged Lepton and a Neutrino in 1 Fb-1 of Pp Collisions at [mml

Search for a Heavy Gauge Boson Decaying to a Charged Lepton and a Neutrino in 1 Fb-1 of Pp Collisions at [mml PDF Author:
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ISBN:
Category :
Languages : en
Pages : 28

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Book Description
The ATLAS detector at the LHC is used to search for heavy charged gauge bosons (W'), decaying to a charged lepton (electron or muon) and a neutrino. Results are presented based on the analysis of pp collisions at a center-of-mass energy of 7 TeV corresponding to an integrated luminosity of 1.04 fb−1. No excess beyond Standard Model expectations is observed. A W' with Sequential Standard Model couplings is excluded at the 95% confidence level for masses up to 2.15 TeV.

Search for the Production of ZW and ZZ Boson Pairs Decaying Into Charged Leptons and Jets in Proton-antiproton Collisions at Sqrt[s]

Search for the Production of ZW and ZZ Boson Pairs Decaying Into Charged Leptons and Jets in Proton-antiproton Collisions at Sqrt[s] PDF Author:
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Languages : en
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Book Description
We present a measurement of the production cross section for ZW and ZZ boson pairs in final states with a pair of charged leptons, from the decay of a Z boson, and at least two jets, from the decay of a W or Z boson, using the full sample of proton-antiproton collisions recorded with the CDF II detector at the Tevatron, corresponding to 8.9 fb(̂-1) of integrated luminosity. We increase the sensitivity to vector boson decays into pairs of quarks using a neural network discriminant that exploits the differences between the spatial spread of energy depositions and charged-particle momenta contained within the jet of particles originating from quarks and gluons. Additionally, we employ new jet energy corrections to Monte Carlo simulations that account for differences in the observed energy scales for quark and gluon jets. The number of signal events is extracted through a simultaneous fit to the dijet mass spectrum in three classes of events: events likely to contain jets with a heavy-quark decay, events likely to contain jets originating from light quarks, and events that fail these identification criteria. We determine the production cross section to be 2.5 +2.0 -1.0 pb (

Search for New Resonances Decaying Via WZ to Leptons in Proton{u2013}proton Collisions at $\sqrt S

Search for New Resonances Decaying Via WZ to Leptons in Proton{u2013}proton Collisions at $\sqrt S PDF Author:
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Category :
Languages : en
Pages : 22

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Book Description
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.

Search for Lepton Flavour Violating Decays of Heavy Resonances and Quantum Black Holes to an E? Pair in Proton-proton Collisions at {u221A}s

Search for Lepton Flavour Violating Decays of Heavy Resonances and Quantum Black Holes to an E? Pair in Proton-proton Collisions at {u221A}s PDF Author:
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Category :
Languages : en
Pages : 25

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Book Description
A search for narrow resonances decaying to an electron and a muon is presented. The $mathrm {e}$ ${mu }$ mass spectrum is also investigated for non-resonant contributions from the production of quantum black holes (QBHs). The analysis is performed using data corresponding to an integrated luminosity of 19.7 $̃text {fb}̂text {-1}$ collected in proton-proton collisions at a centre-of-mass energy of 8 $̃text {TeV}$ with the CMS detector at the LHC. With no evidence for physics beyond the standard model in the invariant mass spectrum of selected $mathrm {e}mu $ pairs, upper limits are set at 95 $%$ confidence level on the product of cross section and branching fraction for signals arising in theories with charged lepton flavour violation. In the search for narrow resonances, the resonant production of a $mathrm { au }$ sneutrino in R-parity violating supersymmetry is considered. The $mathrm { au }$ sneutrino is excluded for masses below 1.28 $̃text {TeV}$ for couplings $lambda _„=lambda _ç=lambda '_ķ=0.01$ , and below 2.30 $̃text {TeV}$ for $lambda _„=lambda _ç=0.07$ and $lambda '_ķ=0.11$ . These are the most stringent limits to date from direct searches at high-energy colliders. In addition, the resonance searches are interpreted in terms of a model with heavy partners of the ${mathrm {Z}} $ boson and the photon. In a framework of TeV-scale quantum gravity based on a renormalization of Newton’s constant, the search for non-resonant contributions to the $mathrm {e}$ ${mu }$ mass spectrum excludes QBH production below a threshold mass $M_{mathrm {th}}$ of 1.99 $̃text {TeV}$ . In models that invoke extra dimensions, the bounds range from 2.36 $̃text {TeV}$ for one extra dimension to 3.63 $̃text {TeV}$ for six extra dimensions. Furthermore, this is the first search for QBHs decaying into the $mathrm {e}$ ${mu }$ final state.