Search For New Physics With Long Lived Particles Decaying To Photons And Missing Energy In Pp Collisions At A Center Of Mass Energy Of 7 Tev With The Cms Experiment At The Lhc
DOWNLOAD
Download Search For New Physics With Long Lived Particles Decaying To Photons And Missing Energy In Pp Collisions At A Center Of Mass Energy Of 7 Tev With The Cms Experiment At The Lhc PDF/ePub or read online books in Mobi eBooks. Click Download or Read Online button to get Search For New Physics With Long Lived Particles Decaying To Photons And Missing Energy In Pp Collisions At A Center Of Mass Energy Of 7 Tev With The Cms Experiment At The Lhc book now. This website allows unlimited access to, at the time of writing, more than 1.5 million titles, including hundreds of thousands of titles in various foreign languages. If the content not found or just blank you must refresh this page
Search For New Physics With Long Lived Particles Decaying To Photons And Missing Energy In Pp Collisions At A Center Of Mass Energy Of 7 Tev With The Cms Experiment At The Lhc
DOWNLOAD
Author : Hongliang Liu
language : en
Publisher:
Release Date : 2011
Search For New Physics With Long Lived Particles Decaying To Photons And Missing Energy In Pp Collisions At A Center Of Mass Energy Of 7 Tev With The Cms Experiment At The Lhc written by Hongliang Liu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with Gauge invariance categories.
We perform a search for long-lived neutral particles decaying into a photon and invisible particles in pp collisions at a center-of-mass energy of 7 TeV at the Large Hadron Collider. In the context of gauge mediated supersymmetry with the lightest neutralino as the next-to-lightest supersymmetric particle and the gravitino as the lightest supersymmetric particle, the neutralino can decay into a gravitino and a photon with a non-zero lifetime. The impact parameter of the photon relative to the beam-beam collision point can be reconstructed using converted photons. The method is sensitive to lifetimes of the order of [Special characters omitted.] (0.1 ns). The data sample corresponds to an integrated luminosity of 2.1 ± 0.1 fb -1 recorded in the first part of 2011 by the CMS experiment at the LHC at [Special characters omitted.] = 7 TeV. The search is performed using events containing photons, missing transverse energy and jets. Upper limits at the 95% confidence level are presented on the cross section for such particles from pair-production, each of which decays into a photon and invisible particles.
Search For New Physics In Pp Collisions At 7 Tev Center Of Mass Energy Using Diphoton Events With Large Missing Transverse Energy In The Cms Experiment At The Lhc
DOWNLOAD
Author : Robert Wayne Stringer
language : en
Publisher:
Release Date : 2011
Search For New Physics In Pp Collisions At 7 Tev Center Of Mass Energy Using Diphoton Events With Large Missing Transverse Energy In The Cms Experiment At The Lhc written by Robert Wayne Stringer and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with Gauge fields (Physics) categories.
Many theoretical models of physics beyond the Standard Model provide a signature of two photons and large missing transverse energy [Special characters omitted.] in the final state. This search was performed using 36 pb[superscript -1] of proton-proton collision data at [Squared root of s] = 7 TeV. The candidate events are determined by comparing the [Special characters omitted.] distribution for events with two photons and at least one hadronic jet with the [Special characters omitted.] T distribution from QCD and electroweak processes that have no true missing transverse energy. 1.2 ± 0.8 background events were expected, with one event observed. This result was interpreted in two theoretical models beyond the Standard Model. The cross section for General Gauge Mediated Supersymmetry Breaking is given an upper limit between 0.3 pb and 1.1 pb. Universal Extra Dimensions has been excluded for all values of 1/ R
Search For New Physics In The Exclusive Delayed E T Final State In Pp Collisions At U221a S
DOWNLOAD
Author :
language : en
Publisher:
Release Date : 2012
Search For New Physics In The Exclusive Delayed E T Final State In Pp Collisions At U221a 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 2012 with categories.
This dissertation presents a search for heavy, long-lived, neutral particles that decay to photons in proton anti-proton collisions with a center of mass energy of 1.96 TeV at the Collider Detector at Fermilab (CDF) experiment. Such particles are typical of models of Gauge Mediated Supersymmetry Breaking (GMSB). We select events with a single photon, missing transverse energy, and little other activity in the detector. We model the photon arrival time for Standard Model and non-collision sources using a data-driven method and consider photons which have a time of arrival at the detector which is significantly delayed relative to predictions. Using 6.3 fb-1 of data collected from December 2004 to June 2010, we observe 322 events in the signal region compared to a background prediction of 287 ± 24 events. While the data are consistently above predictions, we report a model excess with a significance of 1.2 standard deviations from the null hypothesis.
Search For Long Lived Particles Using Delayed Photons In Proton Proton Collisions At 13 Tev With The Cms Detector
DOWNLOAD
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.
A Search For Long Lived Particles That Stop In The Cms Detector And Decay To Muons
DOWNLOAD
Author :
language : en
Publisher:
Release Date : 2016
A Search For Long Lived Particles That Stop In The Cms Detector And Decay To Muons 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 long-lived particles that are produced in proton-proton collisions at the CERN LHC, come to rest in the CMS detector, and decay to muons is presented. The decays of the stopped particles could be observed during the intervals between LHC beam crossings, at times that are well separated from any proton-proton collisions. The analysis uses 19.7 1/fb of 8 TeV data collected by CMS in 2012, during a search interval of 293 hours of trigger livetime. Massive, long-lived particles do not exist in the Standard Model, and so any sign of them would be an indication of new physics. The results are interpreted with a model that predicts a long-lived particle that has a charge of twice the electron charge and that behaves like a lepton. Cross section limits are set for each long-lived particle mass as a function of lifetime, for lifetimes between 100 ns and 10 days. These are the first limits for long-lived stopped particles that decay to muons.
Search For Decays Of Stopped Long Lived Particles Produced In Proton U2013 Proton Collisions At Sqrt S
DOWNLOAD
Author :
language : en
Publisher:
Release Date : 2015
Search For Decays Of Stopped Long Lived Particles Produced 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 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 æs and 1000 s. Finally, these results are the most stringent constraints on stopped particles to date.
Search For New Physics In The Exclusive Gamma Met Final State In P Pbar Collisions At Sqrt S
DOWNLOAD
Author : Adam Jude Aurisano
language : en
Publisher:
Release Date : 2013
Search For New Physics In The Exclusive Gamma Met Final State In P Pbar Collisions At Sqrt S written by Adam Jude Aurisano and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
This dissertation presents a search for heavy, long-lived, neutral particles that decay to photons in proton anti-proton collisions with a center of mass energy of 1.96 TeV at the Collider Detector at Fermilab (CDF) experiment. Such particles are typical of models of Gauge Mediated Supersymmetry Breaking (GMSB). We select events with a single photon, missing transverse energy, and little other activity in the detector. We model the photon arrival time for Standard Model and non-collision sources using a data-driven method and consider photons which have a time of arrival at the detector which is significantly delayed relative to predictions. Using 6.3 fb-1 of data collected from December 2004 to June 2010, we observe 322 events in the signal region compared to a background prediction of 287 ± 24 events. While the data are consistently above predictions, we report a model excess with a significance of 1.2 standard deviations from the null hypothesis. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/148427
Search For Long Lived Neutral Particles Decaying To Quark Antiquark Pairs In Proton Proton Collisions At U221a S
DOWNLOAD
Author :
language : en
Publisher:
Release Date : 2015
Search For Long Lived Neutral Particles Decaying To Quark Antiquark Pairs In Proton Proton Collisions At U221a 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 massive neutral particles decaying to quark-antiquark pairs. The experimental signature is a distinctive topology of a pair of jets, originating at a secondary vertex. Events were collected with the CMS detector at the CERN LHC in proton-proton collisions at a center-of-mass energy of 8 TeV. The data analyzed correspond to an integrated luminosity of 18.5 fb–1. No significant excess is observed above standard model expectations. Upper limits at 95% confidence level are set on the production cross section of a heavy neutral scalar particle, H, in the mass range of 200 to 1000 GeV, decaying promptly into a pair of long-lived neutral X particles in the mass range of 50 to 350 GeV, each in turn decaying into a quark-antiquark pair. For X with mean proper decay lengths of 0.4 to 200 cm, the upper limits are typically 0.5–200 fb. The results are also interpreted in the context of an R-parity-violating supersymmetric model with long-lived neutralinos decaying into a quark-antiquark pair and a muon. For pair production of squarks that promptly decay to neutralinos with mean proper decay lengths of 2–40 cm, the upper limits on the cross section are typically 0.5–3 fb. As a result, the above limits are the most stringent on these channels to date.
Search For Long Lived Particles That Decay Into Final States Containing Two Electrons Or Two Muons In Proton Proton Collisions At Sqrt S
DOWNLOAD
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.
Search For Heavy Long Lived Particles That Decay To Photons In P Bar P Collisions At Sqrt S
DOWNLOAD
Author :
language : en
Publisher:
Release Date : 2007
Search For Heavy Long Lived Particles That Decay To Photons In P Bar P 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 2007 with categories.
This dissertation presents the results of the first search for heavy, neutral, longlived particles that decay to photons at a hadron collider. We use a sample of +jet+missing transverse energy events in $p \bar{p}$ collisions at √s = 1.96 TeV taken with the Collider Detector at Fermilab. Candidate events are selected based on the arrival time of a high-energy photon at the electromagnetic calorimeter as measured with a timing system that was recently installed. The final result is that we find 2 events, using 570±34 pb-1 of data collected during 2004-2005 at the Fermilab Tevatron, consistent with the background estimate of 1.3±0.7 events. While our search strategy does not rely on model-specific dynamics, we interpret this result in terms of cross section limits in a supersymmetric model with $\vec{X}$$0\atop{1}$ eG and set a world-best e 01 mass reach of 101 GeV/c2 at e = 5 ns. We can exclude any [gamma]+jet+missing transverse energy signal that would produce more than 5.5 events.