Search for Physics Beyond the Standard Model in Events with Two Leptons, Jets, and Missing Transverse Momentum in Pp Collisions at {u221A}s
Search for Physics Beyond the Standard Model in Events with Two Leptons, Jets, and Missing Transverse Momentum in Pp Collisions at {u221A}s

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Published: 2015

Total Pages: 41

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Our search is presented for physics beyond the standard model in final states with two opposite-sign same-flavor leptons, jets, and missing transverse momentum. The data sample corresponds to an integrated luminosity of 19.4 fb-1 of proton-proton collisions at √s = 8 TeV collected with the CMS detector at the CERN LHC in 2012. The analysis focuses on searches for a kinematic edge in the invariant mass distribution of the oppositesign same-flavor lepton pair and for final states with an on-shell Z boson. Furthermore, the observations are consistent with expectations from standard model processes and are interpreted in terms of upper limits on the production of supersymmetric particles.

Search for New Physics in Final States with Two Opposite-sign, Same-flavor Leptons, Jets, and Missing Transverse Momentum in Pp Collisions at $\sqrt{s}$
Search for New Physics in Final States with Two Opposite-sign, Same-flavor Leptons, Jets, and Missing Transverse Momentum in Pp Collisions at $\sqrt{s}$

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Published: 2016

Total Pages:

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A search is presented for physics beyond the standard model in final states with two opposite-sign, same-flavor leptons, jets, and missing transverse momentum. The data sample corresponds to an integrated luminosity of 2.3 inverse femtobarns of proton-proton collisions at sqrt(s)=13 TeV collected with the CMS detector at the LHC in 2015. The analysis uses the invariant mass of the lepton pair, searching for a kinematic edge or a resonant-like excess compatible with the Z boson mass. Both search modes use several event categories in order to increase the sensitivity to new physics. These categories are based on the rapidity of the leptons, the multiplicity of jets and b jets, the scalar sum of jet transverse momenta, and missing transverse momentum. In addition, phase space regions are included for which excesses were reported using the sqrt(s)=8 TeV data. A local significance of 2.6 sigma for a kinematic edge search was observed by the CMS Collaboration, and of 3.0 sigma for events compatible with the Z boson mass by the ATLAS Collaboration. The observations in all signal regions are consistent with the expectations from the standard model, and the results are interpreted in the context of simplified models of supersymmetry.

Search for New Phenomena in Three- Or Four-lepton Events in Pp Collisions at [square Root]s
Search for New Phenomena in Three- Or Four-lepton Events in Pp Collisions at [square Root]s

Author: [Study Group] ATLAS Collaboration CERN

Publisher:

Published: 2022

Total Pages: 0

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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

Search for New Physics in Events with Same-sign Dileptons and Jets in Pp Collisions at $\sqrt{s}$
Search for New Physics in Events with Same-sign Dileptons and Jets in Pp Collisions at $\sqrt{s}$

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Published: 2014

Total Pages: 45

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A search for new physics is performed based on events with jets and a pair of isolated, same-sign leptons. The results are obtained using a sample of proton-proton collision data collected by the CMS experiment at a centre-of-mass energy of 8 TeV at the LHC, corresponding to an integrated luminosity of 19.5 inverse femtobarns. In order to be sensitive to a wide variety of possible signals beyond the standard model, multiple search regions defined by the missing transverse energy, the hadronic energy, the number of jets and b-quark jets, and the transverse momenta of the leptons in the events are considered. No excess above the standard model background expectation is observed and constraints are set on a number of models for new physics, as well as on the same-sign top-quark pair and quadruple-top-quark production cross sections. As a result, information on event selection efficiencies is also provided, so that the results can be used to confront an even broader class of new physics models.

A Search for New Physics in Final States With Two Opposite-SignSame-Flavor Leptons, Jets, and Missing Transverse Energy InProton-Proton Collisions with a Center of Mass Energy of 13 TeV
A Search for New Physics in Final States With Two Opposite-SignSame-Flavor Leptons, Jets, and Missing Transverse Energy InProton-Proton Collisions with a Center of Mass Energy of 13 TeV

Author: Charles Vincent Welke

Publisher:

Published: 2016

Total Pages: 142

ISBN-13:

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A search is performed in final states with Z$\rightarrow\ell\ell$, jets, and missing transverse momentum using data collected with the CMS detector at the CERN LHC in 2015 corresponding to an integrated luminosity of 2.3~\fbinv of pp collisions at $\sqrt{s}=13$\TeV. Signal regions are defined to maximize sensitivity to new physics including one to search where ATLAS reported a 3.0~$\sigma$ excess at 8~TeV. The observations in all regions are consistent with the predicted standard model backgrounds, and the results are interpreted in the context of simplified models of supersymmetry.

Search for New Phenomena in Final States with an Energetic Jet and Large Missing Transverse Momentum in Pp Collisions at \(\sqrt{s{\mathrm{}}}
Search for New Phenomena in Final States with an Energetic Jet and Large Missing Transverse Momentum in Pp Collisions at \(\sqrt{s{\mathrm{}}}

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Published: 2015

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Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb-1 of \(\sqrt{s{\mathrm{}}} = 8\) TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT>120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between EmissT>150 GeV and EmissT>700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. Limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presented.

Search for New Physics in the Multijet and Missing Transverse Momentum Final State in Proton-proton Collisions at $\sqrt{s}$
Search for New Physics in the Multijet and Missing Transverse Momentum Final State in Proton-proton Collisions at $\sqrt{s}$

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Publisher:

Published: 2014

Total Pages: 38

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A search for new physics is performed in multijet events with large missing transverse momentum produced in proton-proton collisions at $\sqrt{s}$ = 8 TeV using a data sample corresponding to an integrated luminosity of 19.5 fb−1collected with the CMS detector at the LHC. The data sample is divided into three jet multiplicity categories (3-5, 6-7, and ≥8 jets), and studied further in bins of two variables: the scalar sum of jet transverse momenta and the missing transverse momentum. The observed numbers of events in various categories are consistent with backgrounds expected from standard model processes. Exclusion limits are presented for several simplified supersymmetric models of squark or gluino pair production.

Search for New Physics in Events with High Jet Multiplicity and Low Missing Transverse Momentum in Proton-proton Collisions at $\sqrt{s}
Search for New Physics in Events with High Jet Multiplicity and Low Missing Transverse Momentum in Proton-proton Collisions at $\sqrt{s}

Author:

Publisher:

Published: 2016

Total Pages:

ISBN-13:

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A dedicated search is presented for new phenomena in inclusive eight- and ten-jet final states with low missing transverse momentum, with and without identification of jets originating from b quarks. The analysis is based on data from proton-proton collisions corresponding to an integrated luminosity of 19.6 inverse femtobarns collected with the CMS detector at the LHC at sqrt(s) = 8 TeV. The dominant multijet background expectations are obtained from low jet multiplicity control samples. Data agree well with the standard model background predictions, and limits are set in several benchmark models. Colorons (axigluons) with masses between 0.6 and 0.75 (up to 1.15) TeV are excluded at 95% confidence level. Similar exclusion limits for gluinos in R-parity violating supersymmetric scenarios are from 0.6 up to 1.1TeV. These results comprise the first experimental probe of the coloron and axigluon models in multijet final states.