Download or read book Model Independent Search for New Phenomena in Pp Collisions At u221A s written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We describe a model independent search for physics beyond the standard model in lepton final states. We examine 117 final states using 1.1 fb-1 of pp collisions data at √s = 1.96 TeV collected with the D0 detector. We conclude that all observed discrepancies between data and model can be attributed to uncertainties in the standard model background modeling, and hence we do not see any evidence for physics beyond the standard model.

Download or read book Model Independent Search for New Phenomena in p bar p Collisions at sqrt s written by and published by . This book was released on 2011 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: We describe a model independent search for physics beyond the standard model in lepton final states. We examine 117 final states using 1.1 fb−1 of p{bar p} collisions data at √s = 1.96 TeV collected with the D0 detector. We conclude that all observed discrepancies between data and model can be attributed to uncertainties in the standard model background modeling, and hence we do not see any evidence for physics beyond the standard model.

Download or read book A Search for New Phenomena in Pp Collisions at sqrt s written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Search for New Phenomena in Three Or Four lepton Events 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 with minimal model dependence for physics beyond the Standard Model in events featuring three or four charged leptons (3l and 4l, ) is presented. The analysis aims to be sensitive to a wide range of potential new-physics theories simultaneously. This analysis uses data from pp collisions delivered by the Large Hadron Collider at a centre-of-mass energy of TeV and recorded with the ATLAS detector, corresponding to the full Run 2 dataset of 139 fb−1. The 3l and 4l phase space is divided into 22 event categories according to the number of leptons in the event, the missing transverse momentum, the invariant mass of the leptons, and the presence of leptons originating from a Z-boson candidate. These event categories are analysed independently for the presence of deviations from the Standard Model. No statistically significant deviations from the Standard Model predictions are observed. Upper limits for all signal regions are reported in terms of the visible cross-section

Download or read book Searches for New Phenomena Using Events with Three Or More Charged Leptons in pp Collisions at sqrt s written by David Ren-Hwa Yu and published by . This book was released on 2015 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents two searches for phenomena beyond the Standard Model using events with three or more charged leptons. The searches are based on 20.3 fb-1 of proton- proton collision data with a center-of-mass energy of √s = 8 TeV collected by the ATLAS detector at the CERN Large Hadron Collider in 2012. The first is a model-independent search for excesses beyond Standard Model expectations in many signal regions. The events are required to have least three charged leptons, of which at least two are electrons or muons, and at most one is a hadronically decaying [tau] lepton. The selected events are categorized based on the flavor and charge of the leptons, and the signal regions are defined using several kinematic variables sensitive to beyond the Standard Model phenomena. The second search looks for new heavy leptons decaying resonantly to three electrons or muons, two of which are produced through an intermediate Z boson. The resonant decay produces a narrowly- peaked excess in the trilepton mass spectrum. In both cases, no significant excess beyond Standard Model expectations is observed, and the data are used to set limits on models of new physics. The model-independent trilepton search is used to confront a model of doubly charged scalar particles decaying to e[tau] or [mu][tau], excluding masses below 400 GeV at 95% confidence level. The trilepton resonance search is used to test models of vector-like leptons and the type III neutrino seesaw mechanism. The vector-like lepton model is excluded for most of the mass range 114 GeV - 176 GeV, while the type III seesaw model is excluded for most the mass range 100 GeV - 468 GeV. Both searches also present tools to facilitate reinterpretations in the context of other models predicting the production of three or more charged leptons.

Download or read book Search for New Phenomena in Events with a Photon and Missing Transverse Momentum in Pp Collisions at sqrt s written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper, results of a search for new phenomena in events with an energetic photon and large missing transverse momentum with the ATLAS experiment at the Large Hadron Collider are reported. The data were collected in proton-proton collisions at a centre-of-mass energy of 13 TeV and correspond to an integrated luminosity of 3.2 fb-1. The observed data are in agreement with the Standard Model expectations. Exclusion limits are presented in models of new phenomena including pair production of dark matter candidates or large extra spatial dimensions. In a simplified model of dark matter and an axial-vector mediator, the search excludes mediator masses below 710 GeV for dark matter candidate masses below 150 GeV. In an effective theory of dark matter production, values of the suppression scale M * up to 570 GeV are excluded and the effect of truncation for various coupling values is reported. Finally, for the ADD large extra spatial dimension model the search places more stringent limits than earlier searches in the same event topology, excluding M D up to about 2.3 (2.8) TeV for two (six) additional spatial dimensions; the limits are reduced by 20-40% depending on the number of additional spatial dimensions when applying a truncation procedure.

Download or read book Search for a Heavy Neutral Particle Decaying to E E Or in Pp 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: This Letter presents a search for a heavy neutral particle decaying into an opposite-sign different-flavor dilepton pair, e±?∓, e±?∓, or ?±?∓ using 20.3 fb-1 of pp collision data at √s = 8 TeV collected by the ATLAS detector at the LHC. The numbers of observed candidate events are compatible with the standard model expectations. Limits are set on the cross section of new phenomena in two scenarios: the production of ????????? in R-parity-violating supersymmetric models and the production of a lepton-flavor-violating Ź vector boson.

Download or read book Search for New Phenomena in Dijet Angular Distributions 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 for new phenomena in LHC proton-proton collisions at a center-of-mass energy of √s=8 TeV was performed with the ATLAS detector using an integrated luminosity of 17.3 fb-1. The angular distributions are studied in events with at least two jets; the highest dijet mass observed is 5.5 TeV. All angular distributions are consistent with the predictions of the standard model. In a benchmark model of quark contact interactions, a compositeness scale below 8.1 TeV in a destructive interference scenario and 12.0 TeV in a constructive interference scenario is excluded at 95% C.L.; median expected limits are 8.9 TeV for the destructive interference scenario and 14.1 TeV for the constructive interference scenario.

Download or read book Search for a Heavy Neutral Particle Decaying to E Mu E Tau Or Mu Tau in Pp 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: This Letter presents a search for a heavy neutral particle decaying into an opposite-sign different-flavor dilepton pair, e±?∓, e±?∓, or ?±?∓ using 20.3 fb-1 of pp collision data at √s=8 TeV collected by the ATLAS detector at the LHC. The numbers of observed candidate events are compatible with the standard model expectations. Limits are set on the cross section of new phenomena in two scenarios: the production of ????????? in R-parity-violating supersymmetric models and the production of a lepton-flavor-violating Z' vector boson.

Download or read book Search for New Phenomena in Final States with an Energetic Jet and Large Missing Transverse Momentum in Pp Collisions at S written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses proton-proton collision data corresponding to an integrated luminosity of 3.2 fb–1 at √s=13 TeV collected in 2015 with the ATLAS detector at the Large Hadron Collider. Events are required to have at least one jet with a transverse momentum above 250 GeV and no leptons. Several signal regions are considered with increasing missing-transverse-momentum requirements between EmissT > 250 GeV and EmissT > 700 GeV. Good agreement is observed between the number of events in data and Standard Model predictions. Here, the results are translated into exclusion limits in models with large extra spatial dimensions, pair production of weakly interacting dark-matter candidates, and the production of supersymmetric particles in several compressed scenarios.

Download or read book Search for New Physics in the Exclusive Delayed E t Final State in Pp Collisions at u221A S written by and published by . This book was released on 2012 with total page 164 pages. 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.

Download or read book Search for High mass Diphoton Resonances in pp 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: This article describes a search for high-mass resonances decaying to a pair of photons using a sample of 20.3 fb-1 of pp collisions at √s = 8 TeV recorded with the ATLAS detector at the Large Hadron Collider. The data are found to be in agreement with the Standard Model prediction, and limits are reported in the framework of the Randall-Sundrum model. This theory leads to the prediction of graviton states, the lightest of which could be observed at the Large Hadron Collider. A lower limit of 2.66 (1.41) TeV at 95% confidence level is set on the mass of the lightest graviton for couplings of k/M¯Pl = 0.1 (0.01).

Download or read book Search for New Phenomena in Monophoton Final States in Proton u2013 proton Collisions at written by and published by . This book was released on 2016 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Search for Physics Beyond the Standard Model in Multi jet Events Recorded with the ATLAS Detector in P p Collisions at Square Root of S written by Kuhan Wang and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "A search for physics beyond the Standard Model with multi-jet signatures ispresented using 20.3 inverse fb of proton-proton collision data recorded using theATLAS detector at the Large Hadron Collider at a center-of-mass energy of 8 TeV.An original fit and extrapolation technique is used to estimate the QCD multi-jetbackground. No statistically significant deviations from Standard Model predic-tions are observed. The results are interpreted in terms of model-independent lim-its on the fiducial production cross section of multi-jet events and model-dependentlimits in the context of TeV-scale gravity. The fiducial limits at 95% confidence levelon multi-jet production are as low as 0.16 fb and the exclusion power in thresholdmass for black hole and string ball production varies from 4.6 to 6.2 TeV for par-ticular models. These results are amongst the most stringent limits on TeV-scalegravity to date." --

Download or read book Search for New Phenomena in Dijet Angular Distributions in Proton proton Collisions at math Display written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, a search for new phenomena in LHC proton-proton collisions at a center-of-mass energy of √s=8 TeV was performed with the ATLAS detector using an integrated luminosity of 17.3 fb-1. The angular distributions are studied in events with at least two jets; the highest dijet mass observed is 5.5 TeV. All angular distributions are consistent with the predictions of the standard model. In a benchmark model of quark contact interactions, a compositeness scale below 8.1 TeV in a destructive interference scenario and 12.0 TeV in a constructive interference scenario is excluded at 95% C.L.; median expected limits are 8.9 TeV for the destructive interference scenario and 14.1 TeV for the constructive interference scenario.

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 New Phenomena in Dijet Angular Distributions in Proton proton Collisions at S written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, a search for new phenomena in LHC proton-proton collisions at a center-of-mass energy of √s=8 TeV was performed with the ATLAS detector using an integrated luminosity of 17.3 fb-1. The angular distributions are studied in events with at least two jets; the highest dijet mass observed is 5.5 TeV. All angular distributions are consistent with the predictions of the standard model. In a benchmark model of quark contact interactions, a compositeness scale below 8.1 TeV in a destructive interference scenario and 12.0 TeV in a constructive interference scenario is excluded at 95% C.L.; median expected limits are 8.9 TeV for the destructive interference scenario and 14.1 TeV for the constructive interference scenario.