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Search for New Physics with a Same-sign Dilepton Pair at a Center-of-mass Energy of 13 TeV at the CMS Detector

2016
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Release : 2016
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Book Rating : 141/5 ( reviews)

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Book Synopsis Search for New Physics with a Same-sign Dilepton Pair at a Center-of-mass Energy of 13 TeV at the CMS Detector by : Christopher Alexandre George

Download or read book Search for New Physics with a Same-sign Dilepton Pair at a Center-of-mass Energy of 13 TeV at the CMS Detector written by Christopher Alexandre George. This book was released on 2016. Available in PDF, EPUB and Kindle. Book excerpt: An inclusive search for new physics is performed with a 13 TeV dataset from the CMS detector (May--November 2015, corresponding to 2.32/fb) using events with at least two leptons with the same electrical charge, missing transverse energy, and significant hadronic activity. No significant excesses are reported above the Standard Model background predictions. Constraints are set on a number of new physics models. As motivation, a thorough pedagogical review of the Standard Model and its shortcomings is presented in the first two chapters.

Search for New Physics in Same-sign Dilepton Events in Proton-proton Collisions at {u221A}s

2016
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Release : 2016
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Book Synopsis Search for New Physics in Same-sign Dilepton Events in Proton-proton Collisions at {u221A}s by :

Download or read book Search for New Physics in Same-sign Dilepton Events in Proton-proton Collisions at {u221A}s written by . This book was released on 2016. Available in PDF, EPUB and Kindle. Book excerpt: A search for new physics is performed using events with two isolated same-sign leptons, two or more jets, and missing transverse momentum. The results are based on a sample of proton-proton collisions at a center-of-mass energy of 13 TeV recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of 2.3 fb1. Multiple search regions are defined by classifying events in terms of missing transverse momentum, the scalar sum of jet transverse momenta, the transverse mass associated with a W boson candidate, the number of jets, the number of b quark jets, and the transverse momenta of the leptons in the event. The analysis is sensitive to a wide variety of possible signals beyond the standard model. No excess above the standard model background expectation is observed. Constraints are set on various supersymmetric models, with gluinos and bottom squarks excluded for masses up to 1300 and 680 GeV, respectively, at the 95% confidence level. Upper limits on the cross sections for the production of two top quark-antiquark pairs (119 fb) and two same-sign top quarks (1.7 pb) are also obtained. Furthermore, selection efficiencies and model independent limits are provided to allow further interpretations of the results.

Search for New Physics in a Final State with Same-Sign Dileptons, Jets, and Missing Transverse Energy at 7 TeV Center of Mass Energy

2012
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Release : 2012
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Book Synopsis Search for New Physics in a Final State with Same-Sign Dileptons, Jets, and Missing Transverse Energy at 7 TeV Center of Mass Energy by :

Download or read book Search for New Physics in a Final State with Same-Sign Dileptons, Jets, and Missing Transverse Energy at 7 TeV Center of Mass Energy written by . This book was released on 2012. Available in PDF, EPUB and Kindle. Book excerpt: We report on a search for new physics in a final state with two same sign leptons, missing transverse energy, and significant hadronic activity at a center of mass energy $\sqrt{s}$ = 7 TeV. The data were collected with the CMS detector at the CERN LHC and correspond to an integrated luminosity of 0.98 $\mathrm{fb}^{-1}$. Data--driven methods are developed to estimate the dominant Standard Model backgrounds. No evidence for new physics is observed. The dominant background to the analysis comes from failures of lepton identification in Standard Model $t\bar{t}$ events. The $t\bar{t}$ production cross section in the dilepton final state is measured using 3.1 $\mathrm{fb}^{-1}$ of data. The cross section is measured to be 194 $\pm$ 72 (stat) $\pm$ 24 (syst) $\pm$ 21 (lumi) pb. An algorithm is developed that uses tracking information to improve the reconstruction of missing transverse energy. The reconstruction of missing transverse energy is commissioned using the first collisio ns recorded at 0.9, 2.36 and 7 TeV data. Events with abnormally large values of missing transverse energy are identified as arising from anomalous signals in the calorimeters. Tools are developed to identify and remove these anomalous signals.

Search for New Physics in Fully Hadronic Nal States Using the MT2 Variable at a Center-of-mass Energy of 13 TeV with the CMS Detector

2016
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Release : 2016
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Book Rating : 391/5 ( reviews)

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Book Synopsis Search for New Physics in Fully Hadronic Nal States Using the MT2 Variable at a Center-of-mass Energy of 13 TeV with the CMS Detector by : Jason Gran

Download or read book Search for New Physics in Fully Hadronic Nal States Using the MT2 Variable at a Center-of-mass Energy of 13 TeV with the CMS Detector written by Jason Gran. This book was released on 2016. Available in PDF, EPUB and Kindle. Book excerpt: An inclusive search for new physics in events with fully hadronic final states using the MT2 variable is presented. The results are based on a sample of 13 TeV center-of-mass energy proton-proton collisions, corresponding to 2.3 fb-1 of integrated luminosity collected with the CMS detector at the LHC in 2015. No excess event yield above the Standard Model background expectation is observed. The results are interpreted as limits on simplified models of supersymmetry, expressed as limits on the masses of potential new colored particles. Assuming a stable LSP with mass less than 500 GeV, gluino masses up to 1550-1750 are excluded at 95% confidence level, depending on the gluino decay mechanism. For models of direct squark pair production, top squarks with masses up to 800 GeV are excluded. Bottom squarks with masses up to 880 GeV are excluded. Light flavor squarks with masses up to 600-1260 GeV, depending on the degeneracy of squark masses, are excluded.

Search for New Physics in Same-Sign Dilepton Events in the CMS Detector at the Large Hadron Collider

2014
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Release : 2014
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Book Synopsis Search for New Physics in Same-Sign Dilepton Events in the CMS Detector at the Large Hadron Collider by : Lana Muniz

Download or read book Search for New Physics in Same-Sign Dilepton Events in the CMS Detector at the Large Hadron Collider written by Lana Muniz. This book was released on 2014. Available in PDF, EPUB and Kindle. Book excerpt: CMS results of a new physics search in same-sign dilepton events with b-tagged jets and missing transverse energy (MET) are being presented. These results cover the full 2012 dataset from the LHC at root(s)=8 TeV, corresponding to 19.5/fb. Isolated same-sign dilepton events are easily detected and rare in the Standard Model (SM), but they occur in abundance in some supersymmetry (SUSY) models. Hence, this channel provides a very clean, low background, search for new physics. Multiple search regions defined by the observables MET, hadronic energy (HT), and number of b-tagged jets are considered. The data agrees with the SM prediction, therefore exclusion limits at 95% C.L. are presented for various simplified SUSY models.

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