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 PDF Download
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Author: Robert Wayne Stringer
Publisher:
ISBN: 9781124771816
Category : Gauge fields (Physics)
Languages : en
Pages : 176
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Book Description
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
Author: Robert Wayne Stringer
Publisher:
ISBN: 9781124771816
Category : Gauge fields (Physics)
Languages : en
Pages : 176
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Book Description
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
Author: Hongliang Liu
Publisher:
ISBN:
Category : Gauge invariance
Languages : en
Pages : 160
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Book Description
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.
Author: Wang Wei
Publisher: World Scientific
ISBN: 9811207410
Category : Science
Languages : en
Pages : 576
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Book Description
The latest of the 'Lepton Photon' symposium, one of the well-established series of meetings in the high-energy physics community, was successfully organized at the South Campus of Sun Yat-sen University, Guangzhou, China, from August 7-12, 2017, where physicists around the world gathered to discuss the latest advancements in the research field.This proceedings volume of the Lepton Photon 2017 collects contributions by the plenary session speakers and the posters' presenters, which cover the latest results in particle physics, nuclear physics, astrophysics, cosmology, and plans for future facilities.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 39
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Book Description
A new measurement of the inclusive production cross section for pp to t t-bar is performed at a center-of-mass energy of 7 TeV using data collected by the CMS experiment at the LHC. The analysis uses a data sample corresponding to an integrated luminosity of 36 inverse picobarns, and is based on the final state with one isolated, high transverse momentum muon or electron, missing transverse energy, and hadronic jets. The ttbar content of the selected events is enhanced by requiring the presence of at least one jet consistent with b-quark hadronization. The measured cross section is 150 +/- 9 (stat.) +/- 17 syst.) +/- 6 (lumi.) pb and is in agreement with higher-order QCD calculations. The combination of this measurement with a previous CMS result based on dileptons gives 154 +/- 17 (stat.+syst.) +/- 6 (lumi.) pb.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 20
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
A search for new phenomena is performed in final states containing one or more jets and an imbalance in transverse momentum in pp collisions at a centre-of-mass energy of 13 TeV. The analysed data sample, recorded with the CMS detector at the CERN LHC, corresponds to an integrated luminosity of 2.3 inverse femtobarns. Several kinematic variables are employed to suppress the dominant background, multijet production, as well as to discriminate between other standard model and new physics processes. The search provides sensitivity to a broad range of new-physics models that yield a stable weakly interacting massive particle. The number of observed candidate events is found to agree with the expected contributions from standard model processes, and the result is interpreted in the mass parameter space of fourteen simplified supersymmetric models that assume the pair production of gluinos or squarks and a range of decay modes. For models that assume gluino pair production, masses up to 1575 and 975 GeV are excluded for gluinos and neutralinos, respectively. For models involving the pair production of top squarks and compressed mass spectra, top squark masses up to 400 GeV are excluded.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 164
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Book Description
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.
Author: Christian W. Fabjan
Publisher: Springer Nature
ISBN: 3030353184
Category : Elementary particles (Physics).
Languages : en
Pages : 1083
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Book Description
This second open access volume of the handbook series deals with detectors, large experimental facilities and data handling, both for accelerator and non-accelerator based experiments. It also covers applications in medicine and life sciences. A joint CERN-Springer initiative, the "Particle Physics Reference Library" provides revised and updated contributions based on previously published material in the well-known Landolt-Boernstein series on particle physics, accelerators and detectors (volumes 21A, B1,B2,C), which took stock of the field approximately one decade ago. Central to this new initiative is publication under full open access
Author: Ryan Ward Kelley
Publisher:
ISBN: 9781303566578
Category :
Languages : en
Pages : 148
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Book Description
A search for new physics is performed using events with isolated same-sign leptons and jets in the final state. Results are based on the full sample of proton-proton collisions collected from the Large Hadron Collider at a center-of-mass energy of 8 TeV with the CMS detector and corresponding to an integrated luminosity of 19.5 fb−1. No excess above the standard model background is observed and constraints on a number of new physics models are set.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 23
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Book Description
In this paper, results are presented from a search for new physics in final states containing a photon and missing transverse momentum. The data correspond to an integrated luminosity of 19.6 fb-1 collected in proton-proton collisions at √s = 8 TeV with the CMS experiment at the LHC. No deviation from the standard model predictions is observed for these final states. New, improved limits are set on dark matter production and on parameters of models with large extra dimensions. In particular, the first limits from the LHC on branon production are found and significantly extend previous limits from LEP and the Tevatron. Finally, an upper limit of 14.0 fb on the cross section is set at the 95% confidence level for events with a monophoton final state with photon transverse momentum greater than 145 GeV and missing transverse momentum greater than 140 GeV.
