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Author : Albert M. Sirunyan
Release : 2019
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Book Synopsis Search for Long-lived Particles Using Delayed Photons in Proton-proton Collisions at √s by : Albert M. Sirunyan
Download or read book Search for Long-lived Particles Using Delayed Photons in Proton-proton Collisions at √s written by Albert M. Sirunyan. This book was released on 2019. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Kevin Patrick McDermott
Release : 2019
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Kind : eBook
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Book Synopsis Search for Long-lived Particles Using Delayed Photons in Proton-proton Collisions at 13 TeV with the CMS Detector by : Kevin Patrick McDermott
Download or read book Search for Long-lived Particles Using Delayed Photons in Proton-proton Collisions at 13 TeV with the CMS Detector written by Kevin Patrick McDermott. This book was released on 2019. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Author :
Release : 2012
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Book Synopsis Search for New Physics in the Exclusive Delayed ?+E(t) Final State in Pp Collisions at {u221A}(S) by :
Download or read book Search for New Physics in the Exclusive Delayed ?+E(t) Final State in Pp Collisions at {u221A}(S) written by . This book was released on 2012. Available in PDF, EPUB and Kindle. Book excerpt: 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.
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Release : 2015
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Book Synopsis Search for Decays of Stopped Long-lived Particles Produced in Proton-proton Collisions at $\sqrt{s} by :
Download or read book Search for Decays of Stopped Long-lived Particles Produced in Proton-proton Collisions at $\sqrt{s} written by . This book was released on 2015. Available in PDF, EPUB and Kindle. Book excerpt: 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.
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Release : 2016
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Book Synopsis Search for Long-lived Charged Particles in Proton-proton Collisions at [math Display by :
Download or read book Search for Long-lived Charged Particles in Proton-proton Collisions at [math Display written by . This book was released on 2016. Available in PDF, EPUB and Kindle. Book excerpt: 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.
