Download or read book A Search for Exotic Particles Decaying to WZ Pairs in Pp Collisions at s written by and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for exotic particles decaying via WZ to final states with electrons and muons is performed using a data sample of pp collisions collected at 7 TeV center-of-mass energy by the CMS experiment at the LHC, corresponding to an integrated luminosity of 4.98 fb-1. A cross section measurement for the production of WZ is also performed on a subset of the collision data. No significant excess is observed over the Standard Model background, so lower bounds at the 95% confidence level are set on the production cross sections of hypothetical particles decaying to WZ in several theoretical scenarios. Assuming the Sequential Standard Model, W' bosons with masses below 1143 GeV/c2 are excluded. New limits are also set for several configurations of Low-Scale Technicolor.

Download or read book 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 published by . This book was released on 2018 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Search for Long lived Neutral Particles Decaying to Quark antiquark Pairs in Proton proton Collisions at u221A s written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Electroweak Physics at the LHC written by Matthias U. Mozer and published by Springer. This book was released on 2016-03-24 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book discusses the recent experimental results obtained at the LHC that involve electroweak bosons. The results are placed into an appropriate theoretical and historical context. The work pays special attention to the rising subject of hadronically decaying bosons with high boosts, documenting the state-of-the-art identification techniques and highlighting typical results. The text is not limited to electroweak physics in the strict sense, but also discusses the use of electroweak vector-bosons as tool in the study of other subjects in particle physics, such as determinations of the proton structure or the search for new exotic particles. The book is particularly well suited for graduate students, starting their thesis work on topics that involve electroweak bosons, as the book provides a comprehensive description of phenomena observable at current accelerators as well as a summary of the most relevant experimental techniques.

Download or read book Search for New High Mass Particles Decaying to Lepton Pairs in P Anti p Collisions at S 1 2 written by and published by . This book was released on 2005 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Search for Pair Production of Strongly Interacting Particles Decaying to Pairs of Jets in p bar p Collisions at sqrt s written by and published by . This book was released on 2013 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Search for Pair produced Long lived Neutral Particles Decaying to Jets in the ATLAS Hadronic Calorimeter in Pp Collisions at 2 written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Search for New T Particles in Final States with Large Jet Multiplicities and Missing Transverse Energy in Pp Collisions at u221A s written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a search for a new particle T decaying to a top quark via T = t + X, where X goes undetected. We use a data sample corresponding to 5.7 fb-1 of integrated luminosity of pp collisions with √s = 1.96 TeV, collected at Fermilab Tevatron by the CDF II detector. Our search for pair production of T' is focused on the hadronic decay channel, pp = TT= tt+XX=bqqbqq + XX. We interpret our results in terms of a model where T is an exotic fourth generation quark and X is a dark matter particle. The data are consistent with standard model expectations. We set a limit on the generic production of TT = tt =+ XX, excluding the fourth generation exotic quarks T at 95% confidence level up to mT = 400 GeV/c2 for mX ≤ 70 GeV/c2.

Download or read book Search for the Production of ZW and ZZ Boson Pairs Decaying Into Charged Leptons and Jets in Proton antiproton Collisions at Sqrt s written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a measurement of the production cross section for ZW and ZZ boson pairs in final states with a pair of charged leptons, from the decay of a Z boson, and at least two jets, from the decay of a W or Z boson, using the full sample of proton-antiproton collisions recorded with the CDF II detector at the Tevatron, corresponding to 8.9 fb(̂-1) of integrated luminosity. We increase the sensitivity to vector boson decays into pairs of quarks using a neural network discriminant that exploits the differences between the spatial spread of energy depositions and charged-particle momenta contained within the jet of particles originating from quarks and gluons. Additionally, we employ new jet energy corrections to Monte Carlo simulations that account for differences in the observed energy scales for quark and gluon jets. The number of signal events is extracted through a simultaneous fit to the dijet mass spectrum in three classes of events: events likely to contain jets with a heavy-quark decay, events likely to contain jets originating from light quarks, and events that fail these identification criteria. We determine the production cross section to be 2.5 +2.0 -1.0 pb (

Download or read book Search for Direct Scalar Top Pair Production in Final States with Two Tau Leptons in Pp Collisions at S written by Ewan Chin Hill and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The ATLAS Experiment at the CERN Large Hadron Collider is a particle physics experiment to study fundamental particles and their interactions at very high energies. Supersymmetry is a theory of new physics beyond the Standard Model of particle physics. A search for directly produced pairs of the supersymmetric partner of the top quark was performed using 20 fb^-1 of proton--proton collision data at a centre of mass energy of 8 TeV taken in 2012. The search targeted a model where the supersymmetric partner of the top quark (``scalar top'') decays via the supersymmetric partner of the tau lepton (``scalar tau'') into the supersymmetric partner of the graviton (``gravitino''). Scalar top candidates were searched for in pp collision events with either two hadronically decaying taus, two light leptons (electrons or muons), or one hadronically decaying tau and one light lepton. The numbers of events passing the analysis selection criteria agree with the Standard Model expectations. Exclusion limits at the 95% confidence level were set as a function of the scalar top and scalar tau masses. Depending on the scalar tau mass, ranging from the 87 GeV limit set by the LEP experiments to a few GeV below the scalar top mass, lower limits between 490 GeV and 640 GeV were placed on the scalar top mass within the model considered.

Download or read book Heavy Neutral Particle Decays to Tau Pairs written by Michail Bachtis and published by Springer. This book was released on 2016-08-27 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work presented in this thesis spans a wide range of experimental particle physics subjects, starting from level-1 trigger electronics to the final results of the search for Higgs boson decay and to tau lepton pairs. The thesis describes an innovative reconstruction algorithm for tau decays and details how it was instrumental in providing a measurement of Z decay to tau lepton pairs. The reliability of the analysis is fully established by this measurement before the Higgs boson decay to tau lepton pairs is considered. The work described here continues to serve as a model for analysing CMS Higgs to tau leptons measurements.

Download or read book Search for Long lived Resonance Decaying to a Dilepton Pair in Pp Collisions at square Root of S written by Siinn Che and published by . This book was released on 2018 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Search for Top squark Pairs Decaying Into Higgs Or Z Bosons in Pp Collisions at arow written by and published by . This book was released on 2014 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Exotic Physics written by D. Acosta and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We report on a search for the pair production of scalar leptoquarks, LQ, using 191 pb{sup -1} of proton-antiproton collision data recorded by the CDF experiment during Run II of the Tevatron. The leptoquarks are sought via their decay into a neutrino and quark yielding missing transverse energy and several jets of large transverse energy. No evidence for leptoquark production is observed, and limits are set on {sigma}(p{bar p} {yields} LQ{ovr OQ}X {yields} v{bar v}q{bar q}X). Using a next-to-leading order theoretical prediction of the cross section for scalar leptoquark production, we exclude first-generation leptoquarks in the mass interval 78 to 117 GeV/c{sup 2} at the 95% confidence level for BR(LQ {yields} vq) = 100%.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Search for Neutral Long lived Particles in Pp Collisions at square Root s written by [Study Group] ATLAS Collaboration CERN and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: A search for decays of pair-produced neutral long-lived particles (LLPs) is presented using 139 fb−1 of proton-proton collision data collected by the ATLAS detector at the LHC in 2015-2018 at a centre-of-mass energy of 13 TeV. Dedicated techniques were developed for the reconstruction of displaced jets produced by LLPs decaying hadronically in the ATLAS hadronic calorimeter. Two search regions are defined for different LLP kinematic regimes. The observed numbers of events are consistent with the expected background, and limits for several benchmark signals are determined. For a SM Higgs boson with a mass of 125 GeV, branching ratios above 10% are excluded at 95% confidence level for values of c times LLP mean proper lifetime in the range between 20 mm and 10 m depending on the model. Upper limits are also set on the cross-section times branching ratio for scalars with a mass of 60 GeV and for masses between 200 GeV and 1 TeV

Download or read book Search for Long lived Weakly Interacting Particles that Decay to Displaced Hadronic Jets in Proton proton Collisions at s written by Preema R. Pais and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Many new physics models predict the existence of neutral, weakly interacting, long-lived particles that can decay within the detector volume, producing a distinctive experimental signature. A search is performed for a pair of such particles, using proton-proton collision data at √s = 8 TeV collected by the ATLAS detector in 2012, corresponding to a total integrated luminosity of 20.3 fb-1. Novel techniques are developed for the reconstruction of displaced decays to hadronic jets in the inner tracking detector and muon spectrometer. No significant deviation is found from the number of background events expected from Standard Model processes. The data are interpreted in terms of Hidden Valley scenarios with a Z' boson mediator. This dissertation presents the first results for a heavy Z' boson decaying to displaced hadronic jets.