Search For Dark Matter And Unparticles In Events With A Z Boson And Missing Transverse Momentum In Proton Proton Collisions At Sqrt S
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Search For Dark Matter And Unparticles In Events With A Z Boson And Missing Transverse Momentum In Proton Proton Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2017
Search For Dark Matter And Unparticles In Events With A Z Boson And Missing Transverse Momentum 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 dark matter and unparticle production at the LHC has been performed using events containing two charged leptons (electrons or muons), consistent with the decay of a Z boson, and large missing transverse momentum. This study is based on data collected with the CMS detector in 2015, corresponding to an integrated luminosity of 2.3 inverse femtobarns of proton-proton collisions at the LHC, at a center-of-mass energy of 13 TeV. No excess over the standard model expectation is observed. Compared to previous searches in this topology, which exclusively relied on effective field theories, the results are interpreted in terms of a simplified model of dark matter production for both vector and axial vector couplings between a mediator and dark matter particles. The first study of this class of models using CMS data at sqrt(s)=13 TeV is presented. Additionally, effective field theories of dark matter and unparticle production are used to interpret the data.
Search For Dark Matter And Unparticles Produced In Association With A Z Boson In Proton Proton Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2016
Search For Dark Matter And Unparticles Produced In Association With A Z Boson 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 evidence of particle dark matter (DM) and unparticle production at the LHC has been performed using events containing two charged leptons, consistent with the decay of a Z boson, and large missing transverse momentum. This study is based on data collected with the CMS detector corresponding to an integrated luminosity of 19.7 inverse femtobarns of pp collisions at the LHC at a center-of-mass energy of 8 TeV. No significant excess of events is observed above the number expected from the standard model contributions. The results are interpreted in terms of 90% confidence level limits on the DM-nucleon scattering cross section, as a function of the DM particle mass, for both spin-dependent and spin-independent scenarios. Limits are set on the effective cutoff scale Lambda, and on the annihilation rate for DM particles, assuming that their branching fraction to quarks is 100%. Additionally, the most stringent 95% confidence level limits to date on the unparticle model parameters are obtained.
Search For Dark Matter Extra Dimensions And Unparticles In Monojet Events In Proton Proton Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2015
Search For Dark Matter Extra Dimensions And Unparticles In Monojet 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.
Results are presented from a search for particle dark matter (DM), extra dimensions, and unparticles using events containing a jet and an imbalance in transverse momentum. The data were collected by the CMS detector in proton-proton collisions at the LHC and correspond to an integrated luminosity of 19.7 fb$^{-1}$ at a centre-of-mass energy of 8 TeV. The number of observed events is found to be consistent with the standard model prediction. Limits are placed on the DM-nucleon scattering cross section as a function of the DM particle mass for spin-dependent and spin-independent interactions. Limits are also placed on the scale parameter $M_\mathrm{D}$ in the ADD model of large extra dimensions, and on the unparticle model parameter $\Lambda_\mathrm{U}$. The constraints on ADD models and unparticles are the most stringent limits in this channel and those on the DM-nucleon scattering cross section are an improvement over previous collider results.
Search For Dark Matter In Events With Missing Transverse Momentum And A Higgs Boson Decaying To Two Photons In Pp Collisions At S U221a
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Author :
language : en
Publisher:
Release Date : 2015
Search For Dark Matter In Events With Missing Transverse Momentum And A Higgs Boson Decaying To Two Photons In Pp Collisions At S U221a 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.
Results of a search for new phenomena in events with large missing transverse momentum and a Higgs boson decaying to two photons are reported. Data from proton-proton collisions at a center-of-mass energy of 8 TeV and corresponding to an integrated luminosity of 20.3 fb-1 have been collected with the ATLAS detector at the LHC. The observed data are well described by the expected standard model backgrounds. Upper limits on the cross section of events with large missing transverse momentum and a Higgs boson candidate are also placed. Exclusion limits are presented for models of physics beyond the standard model featuring dark-matter candidates.
Search For Dark Matter With Atlas
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Author : Ruth Pöttgen
language : en
Publisher: Springer
Release Date : 2016-06-29
Search For Dark Matter With Atlas written by Ruth Pöttgen and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-06-29 with Science categories.
This thesis describes in detail a search for weakly interacting massive particles as possible dark matter candidates, making use of so-called mono-jet events. It includes a detailed description of the run-1 system, important operational challenges, and the upgrade for run-2. The nature of dark matter, which accounts for roughly 25% of the energy-matter content of the universe, is one of the biggest open questions in fundamental science. The analysis is based on the full set of proton-proton collisions collected by the ATLAS experiment at the Large Hadron Collider at √s = 8 TeV. Special attention is given to the experimental challenges and analysis techniques, as well as the overall scientific context beyond particle physics. The results complement those of non-collider experiments and yield some of the strongest exclusion bounds on parameters of dark matter models by the end of the Large Hadron Collider run-1. Details of the upgrade of the ATLAS Central Trigger for run-2 are also included.
Search For Dark Matter In Events With A Highly Energetic Jet And Missing Transverse Momentum In Proton Proton Collisions At Root Out S
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Author : Ruth Pöttgen
language : en
Publisher:
Release Date : 2014
Search For Dark Matter In Events With A Highly Energetic Jet And Missing Transverse Momentum In Proton Proton Collisions At Root Out S written by Ruth Pöttgen 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.
Search For Dark Matter In Final States Containing Semi Visible Jets From Proton Proton Collisions At Square Root S
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Author : Colin Terrence Fallon
language : en
Publisher:
Release Date : 2022
Search For Dark Matter In Final States Containing Semi Visible Jets From Proton Proton Collisions At Square Root S written by Colin Terrence Fallon and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022 with categories.
"This dissertation presents a novel search for new physics using the full Run 2 dataset of 137.6 fb-1 collected by the Compact Muon Solenoid during proton-proton runs of the Large Hadron Collider. The new physics in question is dark matter production in a unique signature called semi-visible jets. Semi-visible jets are produced when a new massive mediator particle emerges from the proton-proton interaction. This mediator then decays to unstable dark matter particles which hadronize and produce a mixture of standard model particles and stable dark matter particles. The stable dark particles are only detectable as missing transverse momentum, and the standard particles are detectable as jets. This produces a signature where two jets are produced, one of which is aligned with the total missing transverse momentum. The search is presented in two phases: a classical cut-based search which uses a series of cuts based on event kinematics to select events which look like the signal signature, and a machine learning based search which uses a technique called boosted decision trees to identify semi-visible jets in a more powerful but model-dependent way. No evidence for Physics Beyond the Standard Model is observed in either search. The classical search excludes the possibility that the mediator could have a mass between 1.5 TeV and 3.98 TeV, while the model-dependent search excludes mediators with masses between 1.5 TeV and 5.08 TeV. Additionally, ranges of other signal parameters are excluded"--Page viii.
Precision Measurement Of And Search For Dark Matter In The Transverse Momentum Spectra Of Z Bosons
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Author : Dylan George Hsu
language : en
Publisher:
Release Date : 2019
Precision Measurement Of And Search For Dark Matter In The Transverse Momentum Spectra Of Z Bosons written by Dylan George Hsu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.
A measurement of the differential Z boson production cross section in proton-proton collisions is presented. It furnishes a precision test of the Standard Model, and constrains the parton distribution functions of the proton. Moreover, it is a building block for future measurements of the mass of the W± boson. A study of the efficiency of lepton identification algorithms is performed which drives the precision of the measurement at lower values of transverse momentum. In tandem, a search for new physics in events with a Z boson produced in association with large missing transverse momentum is presented. The results of this search are interpreted in the context of several dark matter models: generic spin-0 or spin-1 mediators, invisible decays of a Higgs-like boson, unparticles, and large extra spatial dimensions. A multivariate analysis was developed to enhance the sensitivity of the invisible Higgs interpretation. The theoretical uncertainty on the irreducible background from electroweak diboson processes is constrained by emulating the missing energy using pure control samples in the fully leptonic final states. The data were collected with the Compact Muon Solenoid detector at the Large Hadron Collider and correspond to an integrated luminosity of 35.9 fb-1. No significant deviations from the Standard Model are found.
Search For Dark Matter In Proton Proton Collisions At 8 Tev With Missing Transverse Momentum And Vector Boson Tagged Jets
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Author :
language : en
Publisher:
Release Date : 2016
Search For Dark Matter In Proton Proton Collisions At 8 Tev With Missing Transverse Momentum And Vector Boson Tagged Jets 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 is presented for an excess of events with large missing transverse momentum in association with at least one highly energetic jet, in a data sample of proton-proton collisions at a centre-of-mass energy of 8 TeV. The data correspond to an integrated luminosity of 19.7 inverse femtobarns collected by the CMS experiment at the LHC. The results are interpreted using a set of simplified models for the production of dark matter via a scalar, pseudoscalar, vector, or axial vector mediator. Additional sensitivity is achieved by tagging events consistent with the jets originating from a hadronically decaying vector boson. This search uses jet substructure techniques to identify hadronically decaying vector bosons in both Lorentz-boosted and resolved scenarios. This analysis yields improvements of 80% in terms of excluded signal cross sections with respect to the previous CMS analysis using the same data set. No significant excess with respect to the standard model expectation is observed and limits are placed on the parameter space of the simplified models. Mediator masses between 80 and 400 GeV in the scalar and pseudoscalar models, and up to 1.5 TeV in the vector and axial vector models, are excluded.
Search For New Phenomena In Events With A Photon And Missing Transverse Momentum In Pp Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2016
Search For New Phenomena In Events With A Photon And Missing Transverse Momentum In Pp 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.
In this paper, results of a search for new phenomena in events with an energetic photon and large missing transverse momentum with the ATLAS experiment at the Large Hadron Collider are reported. The data were collected in proton-proton collisions at a centre-of-mass energy of 13 TeV and correspond to an integrated luminosity of 3.2 fb-1. The observed data are in agreement with the Standard Model expectations. Exclusion limits are presented in models of new phenomena including pair production of dark matter candidates or large extra spatial dimensions. In a simplified model of dark matter and an axial-vector mediator, the search excludes mediator masses below 710 GeV for dark matter candidate masses below 150 GeV. In an effective theory of dark matter production, values of the suppression scale M * up to 570 GeV are excluded and the effect of truncation for various coupling values is reported. Finally, for the ADD large extra spatial dimension model the search places more stringent limits than earlier searches in the same event topology, excluding M D up to about 2.3 (2.8) TeV for two (six) additional spatial dimensions; the limits are reduced by 20-40% depending on the number of additional spatial dimensions when applying a truncation procedure.