Search For Long Lived Particles Using Delayed Photons In Proton Proton Collisions At 13 Tev With The Cms Detector
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A Search For Displaced Leptons In The Atlas Detector
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Author : Lesya Horyn
language : en
Publisher: Springer Nature
Release Date : 2022-02-07
A Search For Displaced Leptons In The Atlas Detector written by Lesya Horyn and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022-02-07 with Science categories.
This thesis presents a search for long-lived particles decaying into displaced electrons and/or muons with large impact parameters. This signature provides unique sensitivity to the production of theoretical lepton-partners, sleptons. These particles are a feature of supersymmetric theories, which seek to address unanswered questions in nature. The signature searched for in this thesis is difficult to identify, and in fact, this is the first time it has been probed at the Large Hadron Collider (LHC). It covers a long-standing gap in coverage of possible new physics signatures. This thesis describes the special reconstruction and identification algorithms used to select leptons with large impact parameters and the details of the background estimation. The results are consistent with background, so limits on slepton masses and lifetimes in this model are calculated at 95% CL, drastically improving on the previous best limits from the Large Electron Positron Collider (LEP).
Search For Long Lived Particles Using Delayed Photons In Proton Proton Collisions At 13 Tev With The Cms Detector
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Author : Kevin Patrick McDermott
language : en
Publisher:
Release Date : 2019
Search For Long Lived Particles Using Delayed Photons In Proton Proton Collisions At 13 Tev With The Cms Detector written by Kevin Patrick McDermott 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.
This dissertation presents a search for long-lived particles using delayed photons in proton-proton collisions at sqrt(s) = 13 TeV recorded by the Compact Muon Solenoid (CMS) experiment at the CERN Large Hadron Collider in 2017, corresponding to an integrated luminosity of 41.5 fb^-1. This analysis includes a number of unique components that will be discussed: a dedicated signal trigger, out-of-time photon reconstruction and identification, and a detector time resolution measurement. The results of this search include the combination of a related analysis using data collected in 2016 also at sqrt(s) = 13 TeV, corresponding to a combined integrated luminosity of 77.4 fb^-1. The combined results are interpreted in the context of supersymmetry with gauge-mediated supersymmetry breaking, where the neutralino is long-lived and decays to a photon and a gravitino. Limits are presented as a function of the neutralino proper decay length and mass. For neutralino proper decay lengths of 10^1, 10^2, 10^3, and 10^4 cm, masses up to 320, 525, 360, and 215 GeV are excluded at 95% confidence level, respectively. Additionally, a discussion on a high-performance computing upgrade to CMS, known as mkFit, will be presented. mkFit is an on-going effort to exploit highly parallel computer architectures in vectorizing and parallelizing combinatorial Kalman filter charged particle track reconstruction algorithms. The current physics and computational performance of this project will be discussed.
Search For Long Lived Particles Using Delayed Photons In Proton Proton Collisions At S
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Author : Albert M. Sirunyan
language : en
Publisher:
Release Date : 2019
Search For Long Lived Particles Using Delayed Photons In Proton Proton Collisions At S written by Albert M. Sirunyan 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.
Chemical Abstracts
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Author :
language : en
Publisher:
Release Date : 2002
Chemical Abstracts written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with Chemistry categories.
Search For The Decays Of Stopped Exotic Long Lived Particles Produced In P P Collisions At 13 Tev At Cms
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Author : Weifeng Ji
language : en
Publisher:
Release Date : 2018
Search For The Decays Of Stopped Exotic Long Lived Particles Produced In P P Collisions At 13 Tev At Cms written by Weifeng Ji and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with Large Hadron Collider (France and Switzerland) categories.
In this dissertation, I present the searches looking for decays of stopped massive long-lived exotic particles, which are pair produced in the proton-proton collisions at 13 TeV and come to rest afterwards in the CMS detector at the CERN LHC. The decays are most likely to be observed when there are no collisions. Two specific decay scenarios are studied: a long-lived particle (LLP) decaying hadronically or semi- leptonically in the calorimeter, and a LLP decaying semi-leptonically or leptonically to a pair of muons in the muon detector. The calorimeter-based search is performed using 2.7 fb-1 of 13 TeV collision run data collected in 2015 and 35.9 fb-1 of 13 TeV collision run data collected in 2016, corresponding to a total trigger livetime of 721 hours. The muon search is performed using 2.8 fb-1 of 13 TeV collision run data collected in 2015 and 36.2 fb-1 of 13 TeV collision run data collected in 2016, corresponding to a total trigger livetime of 744 hours. Search results are interpreted in a couple of simplified models. The limits on the production cross sections and masses of LLPs are calculated as a function of particle lifetimes, which vary from 100 ns to 10 days, assuming the corresponding decaying branching fractions to be 100%. The results are the most stringent ones on the stopped LLPs so far.
Search For Decays Of Stopped Long Lived Particles Produced In Proton Proton Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2015
Search For Decays Of Stopped Long Lived Particles Produced 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 has been performed for long-lived particles that could have come to rest within the CMS detector, using the time intervals between LHC beam crossings. The existence of such particles could be deduced from observation of their decays via energy deposits in the CMS calorimeter appearing at times that are well separated from any proton-proton collisions. Using a data set corresponding to an integrated luminosity of 18.6 fb-1 of 8 TeV proton-proton collisions, and a search interval corresponding to 281 h of trigger livetime, 10 events are observed, with a background prediction of 13.2+3.6 -2.5 events. Limits are presented at 95 % confidence level on gluino and top squark production, for over 13 orders of magnitude in the mean proper lifetime of the stopped particle. Assuming a cloud model of R-hadron interactions, a gluino with mass ≤1000 GeV and a top squark with mass ≤525 GeV are excluded, for lifetimes between 1 μs and 1000 s. Finally, these results are the most stringent constraints on stopped particles to date.
Search For Long Lived Charged Particles In Proton Proton Collisions At Math Display
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Author :
language : en
Publisher:
Release Date : 2016
Search For Long Lived Charged Particles In Proton Proton Collisions At Math Display 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.
Results are presented of a search for heavy stable charged particles produced in proton-proton collisions at √s = 13 TeV using a data sample corresponding to an integrated luminosity of 2.5 fb-1 collected in 2015 with the CMS detector at the CERN LHC. The search is conducted using signatures of anomalously high energy deposits in the silicon tracker and long time-of-flight measurements by the muon system. The data are consistent with the expected background, and upper limits are set on the cross sections for production of long-lived gluinos, top squarks, tau sleptons, and lepton-like long-lived fermions. These upper limits are equivalently expressed as lower limits on the masses of new states; the limits for gluinos, ranging up to 1610 GeV, are the most stringent to date. Furthermore, limits on the cross sections for direct pair production of long-lived tau sleptons are also determined.
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 Exotic Long Lived Particles Using Disappearing Tracks With The Cms Experiment In Proton Proton Collisions At S
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Author : Viktor Gerhard Kutzner
language : en
Publisher:
Release Date : 2023
Search For Exotic Long Lived Particles Using Disappearing Tracks With The Cms Experiment In Proton Proton Collisions At S written by Viktor Gerhard Kutzner and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023 with categories.
Search For Long Lived Particles That Decay Into Final States Containing Two Electrons Or Two Muons In Proton Proton Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2015
Search For Long Lived Particles That Decay Into Final States Containing Two Electrons Or Two Muons 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 is performed for long-lived particles that decay into final states that include a pair of electrons or a pair of muons. The experimental signature is a distinctive topology consisting of a pair of charged leptons originating from a displaced secondary vertex. Events corresponding to an integrated luminosity of 19.6 (20.5) fb-1 in the electron (muon) channel were collected with the CMS detector at the CERN LHC in proton-proton collisions at √s=8 TeV. No significant excess is observed above standard model expectations. Upper limits on the product of the cross section and branching fraction of such a signal are presented as a function of the long-lived particle's mean proper decay length. The limits are presented in an approximately model-independent way, allowing them to be applied to a wide class of models yielding the above topology. Over much of the investigated parameter space, the limits obtained are the most stringent to date. In the specific case of a model in which a Higgs boson in the mass range 125-1000 GeV/c2 decays into a pair of long-lived neutral bosons in the mass range 20-350 GeV/c2, each of which can then decay to dileptons, the upper limits obtained are typically in the range 0.2-10 fb for mean proper decay lengths of the long-lived particles in the range 0.01-100 cm. In the case of the lowest Higgs mass considered (125 GeV/c2), the limits are in the range 2-50 fb. As a result, these limits are sensitive to Higgs boson branching fractions as low as 10-4.