553 research outputs found
ATLAS and CMS searches for third generation SUSY particles
No full textSearches for supersymmetric partners of the top and bottom quark (top and bottom squark) in a variety of final states are presented. The ATLAS and CMS collaborations have published a large range of results using the respective proton-proton collision data at 13 TeV collected during the LHC Run 2. No significant deviations from the expected SM background rates are observed. Stringent constraints on top and bottom squark masses have been placed, reaching up to 1.3 TeV for some simplified models with a massless lightest neutralino (LSP). These limits are decreased for models with smaller mass splitting between the third generation squarks and the LSP as well as models involving cascade decays or R-parity violating couplings. Interpretations in terms of leptoquark or simplified dark matter models highlight the impact of these results beyond SUSY models.Recent highlights of searches for supersymmetric partners of the top and bottom quark (top and bottom squark) in a variety of final states are presented. The ATLAS and CMS collaborations have published a large range of results using the respective proton-proton collision data at √ s = 13 TeV collected during the LHC Run 2. No significant deviations from the expected SM background rates are observed. Stringent constraints on top and bottom squark masses have been placed, reaching up to 1.3 TeV for some simplified models with a massless lightest neutralino (LSP). These limits are decreased for models with smaller mass splitting between the third generation squarks and the LSP as well as models involving cascade decays or R-parity violating couplings. Interpretations in terms of leptoquark or simplified dark matter models highlight the impact of these results beyond SUSY models
(YSF) Search for top squarks and dark matter particles in opposite-charge dilepton final states at CMS
No full textA search for new physics is presented in final states with two oppositely charged leptons, jets identified as originating from b quarks, and missing transverse momentum using 35.9/fb of CMS data recorded in 2016. Hypothetical signal events are efficiently separated from the dominant top quark pair background with requirements on missing transverse momentum and transverse mass variables, the latter reducing the background by four orders of magnitude. No significant deviation is observed from the expected background. The results are interpreted in terms of simplified models of pair produced scalar partners of top quarks (top squarks), as predicted by supersymmetric models. Exclusion limits reach up to top squark masses of 1.3 TeV for specific model assumptions. Additionally, pair production of dark matter particles via scalar or pseudoscalar mediators is tested, and the analysis provides exclusions of scalar mediators with masses below 100 GeV
Cornering the top squark with the CMS detector
No full textSearches for the superpartner of the top quark are of special interest in the larger context of searches for supersymmetry, as it could play a central role in the solution of the hierarchy problem given its large coupling to the Higgs boson. The CMS Collaboration has looked for hints of top squark production in fully hadronic, semi-leptonic and fully leptonic final states with the whole dataset of proton-proton collisions collected during the Run 2 of the LHC. Advanced, novel strategies for object identification and background reduction, based on machine learning, are used to maximize the sensitivity to new physics for different configurations of the sparticle mass spectrum. Inclusive analyses are complemented by dedicated searches for the most challenging topologies, such as those where the signal mimics the standard model background from top quark pair production. Results from all channels are combined. Moreover, top squark production in R-parity violating and stealth supersymmetry models is searched for with a dedicated analysis. The seminar will present the analysis methods used in these searches and their results.
Cornering the top squark with the CMS detector: https://cern.zoom.us/j/61825141950?pwd=NGptbjY1SVVuN1lpMklXSXVjNm5Ddz0
Suche am CMS-Experiment nach supersymmetrischen Partnern und anomaler Kopplungen des Top-Quarks
No full textDie bekannten Elementarteilchen und deren Wechselwirkungen werden vom Standardmodell der Teilchenphysik (SM) beschrieben. Experimentelle Ergebnisse auf unterschiedlichsten Energieskalen können mithilfe des SM verstanden werden. Trotz dieser Erfolge ist das SM unvollständig, etwa weil die unnatürlich kleine Masse des Higgs-Bosons nicht zufriedenstellend erklärt werden kann. Das SM beinhaltet außerdem kein Teilchen, das die dunkle Materie ausmachen könnte. Diese Unzulänglichkeiten haben zur Entwicklung von Theorien jenseits des SM (BSM) geführt. Die Supersymmetrie (SUSY) ist eine Theorie zur Erweiterung des SM, die die Existenz von neuen Elementarteilchen vorhersagt. In vielen SUSY Szenarien ist die Masse des Top-Squarks nicht viel höher als jene seines SM Partners, dem Top-Quark. Daher könnte es in den hochenergetischen Proton-Proton-Kollisionen am LHC paarweise erzeugt werden. Um nach Hinweisen auf die Produktion der Top-Squarks zu suchen, werden Ereignisse mit zwei gegengleich geladenen Leptonen, Jets von Bottom-Quarks, und einem hohen transversalen Impulsungleichgewicht, selektiert. Die Kollisionsdaten, die für diese Suche verwendet werden, wurden mit dem CMS Experiment im Jahr 2016 bei einer Schwerpunktsenergie von 13 TeV aufgezeichnet. Top-Squarks mit Massen bis zu 1.3 TeV können für bestimmte SUSY Modelle ausgeschlossen werden. Die gemeinsame Produktion eines Top-Quark-Paars mit einem Z-Boson (ttZ) ist der größte irreduzible SM Hintergrund für diese Suche. Eine genaue Messung des Produktionswirkungsquerschnitts dieses Prozesses ist daher eine Möglichkeit, die Sensitivität von SUSY Suchen zu erhöhen. Außerdem sagen viele BSM Theorien eine modifizierte Kopplung des Top-Quarks an das Z-Boson vorher. Um diese Kopplung zu messen werden Ereignisse mit drei Leptonen und zumindest einem Jet von einem Bottom-Quark aus den 2016 und 2017 aufgezeichneten Kollisionsdaten des CMS Experiments selektiert. Die große Anzahl an aufgezeichneten Kollisionen ermöglicht die differenzielle Messung des ttZ Wirkungsquerschnitts und erlaubt daher eine Einschränkung der anomalen Kopplungen des Top-Quarks.The standard model of particle physics (SM) comprises our current understanding of elementary particles and their interactions. Several shortcomings of the SM, such as the naturalness problem of the Higgs boson and the lack of a viable dark matter candidate, motivate searches for physics beyond the SM (BSM). Supersymmetry (SUSY) is among the most promising theories to extend the SM and predicts the existence of several new elementary particles. In many SUSY scenarios, the mass of the top squark, the SUSY partner of the SM top quark, is expected to be not much larger than the top quark mass, enabling its pair production in the high energetic proton-proton collisions at the LHC. Events with two oppositely charged leptons, jets identified as originating from b quarks, and large missing transverse momentum are selected from collision data collected by the CMS experiment in order to search for hints of top squark pair production. Under certain model assumptions, the search is sensitive to the production of top squarks with masses up to 1.3 TeV. The production of a Z boson in association with a top quark pair (ttZ) is a large irreducible background for this search. A precise measurement of its cross section is therefore of great importance to reduce systematic uncertainties. Additionally, the coupling of the top quark to the Z boson is sensitive to corrections from physics beyond the standard model and is therefore a promising probe of new physics. A sample with high purity of ttZ events is selected by requiring at least three charged leptons, out of which two leptons with same flavor form a Z boson candidate, and at least one jet is required to be b-tagged. Measurements of the momentum of the Z boson candidate and the angular distribution its decay products are used to set tight direct constraints on anomalous top quark couplings
Suche nach Supersymmetrie mit dem CMS-Experiment in pp-Kollisionen bei 13 TeV mit einem Lepton im Endzustand
No full textSupersymmetry is among the most promising theories of physics beyond the Standard Model, but until now any direct evidence in its support is still missing. A search for events with a single charged lepton in the final state, coming from supersymmetric processes, is performed using proton-proton collision data taken by the CMS experiment at the CERN LHC in the 2015 run with a center of mass energy of 13 TeV. The integrated luminosity of the dataset corresponds to 2.3fb-1. The signal model describes gluino pair production with masses in the TeV range. The cascade decay of each gluino involves production of 1st and 2nd generation quark jets and a neutral stable supersymmetric particle in the final state, the lightest neutralino, which provides a significant amount of missing transverse energy. Exactly one charged lepton is required in the final state, which comes from the decay of one of the involved W bosons. At the same time, multijet events are highly suppressed by this requirement. The other W boson will decay hadronically. After applying a baseline selection to suppress the bulk of background events, the re- maining events are split into a few signal regions with different kinematic requirements. A robust method to estimate background events from Standard Model processes using control samples in data is then introduced. This method is validated both in simu- lated samples and in data. Systematic uncertainties of the background prediction and simulated signal samples are studied. The observation in the signal regions is in good agreement with the expectation from the Standard Model. Therefore, exclusion limits on gluino and neutralino masses of the tested model are set. Gluinos with masses up to 1400 GeV and neutralinos up to 850 GeV are excluded with 95% confidence level in the considered model, improving previous mass limits by several hundred GeVs
Service Design Thinking and social Organizations. Social Organizations as a source of social innovations and the role of Service Design Thinking
No full textDiese Arbeit beschäftigt sich mit sozialwirtschaftlichen Organisationen als Entstehungsort für soziale Innovationen und der Rolle von Service Design Thinking. Ziel der Arbeit ist es, eine theoretische Grundlage mit den Begrifflichkeiten soziale Innovation und Sozialwirtschaft zu schaffen. Es sollen Denkanstöße gegeben werden, wie ein innovationsförderliches Umfeld beschaffen sein soll und welche Rahmenbedingungen Organisationen bereitstellen können. Die Arbeit möchte der Leserin/ dem Leser einen fundierten Einblick in die Kernprinzipien des Service Design Thinking und dessen Anwendungsbereich in der Entwicklung von sozialen Dienstleistungen geben.
Durch die Forschung wird der Frage nachgegangen, inwiefern sozialwirtschaftliche Organisationen ein Entstehungsort für soziale Innovationen sein können und wie sich das konkrete Arbeiten an innovativen Ideen gestaltet. Der Fokus liegt auf dem methodischen Vorgehen und der Rolle von Service Design Thinking.
Um Daten aus der Praxis zu erheben, hat die Autorin leitfadengestützte Expert*inneninterviews durchgeführt und diese mit Hilfe der qualitativen Inhaltsanalyse nach Mayring ausgewertet.
Die Ergebnisse zeigen, dass sozialwirtschaftliche Organisationen ein wichtiger Entstehungsort für soziale Innovationen sind. Die Organisationen müssen, um ihr Innovationspotential gut auszuschöpfen zu können, Rahmenbedingungen schaffen, damit Arbeiten an sozialen Innovationen ermöglicht wird. Sie sollen sich intern und extern besser vernetzen und sich methodisch gut ausstatten. Die Ergebnisse zeigen auch, dass für das Entwickeln neuer Dienstleistungen ein systematischer und strukturierter Ablauf, gefüttert mit zahlreichen Methoden wichtig ist. Die Klient*innenperspektive muss konsequent eingebracht werden. Offenheit, Freiräume, und eine gewisse Fehlerkultur sind Voraussetzung für Kreativprozesse. Service Design Thinking schafft nicht nur hilfreiche Rahmenbedingungen, um Ideen zu generieren und Innovationsprozesse zu durchlaufen, sondern hat auch den Nebeneffekt durch gewisse Arbeitssettings strukturelle und kulturelle Veränderungen anzustoßen.This thesis deals with socio-economic organizations as a place of origin for social innovations and the role of Service Design Thinking. The aim of the work is to create a theoretical basis with the terms social innovation and social economy. Food for thought should be given as to how an innovation friendly environment should look like and what framework conditions organizations can provide. The thesis would like to give the reader a profound insight into the core principles of Service Design Thinking and its scope in the development of social services.
The research investigates the extent to which socio-economic organizations can be a place of origin for social innovations and how concrete work on innovative ideas is shaped. The focus is on the methodical approach and the role of Service Design Thinking.
In order to collect data from practice, the author carried out guideline-based expert interviews and evaluated them with the help of the qualitative content analysis according to Mayring.
The results show that social- economic organizations are an important source of social innovation. In order to fully take advantage of their innovation potential, the organizations must create framework conditions so that work on social innovations is made possible. They should network better internally and externally and be methodologically well equipped. The results also show that a systematic and structured process, fed with numerous methods, is important for developing new services. The client's perspective must be brought in consistently. Openness, freedom and a certain error culture are prerequisites for creative processes. Service Design Thinking not only creates helpful framework conditions for generating ideas and going through innovation processes, but also has the side effect of initiating structural and cultural changes through certain work settings.vorgelegt von: Sonja SpitzbartWien, FH Campus Wien, Masterarb., 202
A Water Perspective on Land Competition
No full textThis chapter reflects on land competition from a water perspective. Conceptual thoughts are enriched with evidence drawn from case studies as well as other published studies about both land and water. At the same time, it lays down an analytical framework for these case studies. Starting with a discussion of the inherent relationship between land and water, we explore recent disconnects in land and water studies that make it difficult to collate empirical evidence and comprehensive understanding of how competition between water and land are inherently linked. For us the term competition refers to gaining access to or control over—either land or water—and thus simultaneously captures social and material dimensions. To address these linkages, we employ the concept of waterscapes. One way of seeing waterscapes is through the lens of the competition that occurs at specific places, in various positions and on/across various scales, thereby capturing a combined view of land and water. The notion of waterscapes is mainly used by scholars from the fields of political ecology and critical geography thinking to explore how power is wielded, and in determining when and where who or what gets how much water/land. We briefly review the different notions of competition in disconnected literature concerning land and water in order to instil a further analytical dimension: whilst the term “competition” is increasingly used in land change science to refer to the global rush for land, water scholars refer rather to the various means of water governance
Predicting Chandra CCD Degradation with the Chandra Radiation Model
No full textNot long after launch of the Chandra X-Ray Observatory, it was discovered that the Advanced CCD Imaging Spectrometer (ACIS) detector was rapidly degrading due to radiation. Analysis by Chandra personnel showed that this degradation was due to 10w energy protons (100 - 200 keV) that scattered down the optical path onto the focal plane. In response to this unexpected problem, the Chandra Team developed a radiation-protection program that has been used to manage the radiation damage to the CCDs. This program consists of multiple approaches - scheduled sating of the ACIS detector from the radiation environment during passage through radiation belts, real-time monitoring of space weather conditions, on-board monitoring of radiation environment levels, and the creation of a radiation environment model for use in computing proton flux and fluence at energies that damage the ACIS detector. This radiation mitigation program has been very successful. The initial precipitous increase in the CCDs' charge transfer inefficiency (CTI) resulting from proton damage has been slowed dramatically, with the front-illuminated CCDS having an increase in CTI of only 2.3% per year, allowing the ASIS detector's expected lifetime to exceed requirements. This paper concentrates on one aspect of the Chandra radiation mitigation program, the creation of the Chandra Radiation Model (CRM). Because of Chandra's highly elliptical orbit, the spacecraft spends most of its time outside of the trapped radiation belts that present the severest risks to the ACIS detector. However, there is still a proton flux environment that must be accounted for in all parts of Chandra's orbit. At the time of Chandra's launch there was no engineering model of the radiation environment that could be used in the outer regions of the spacecraft's orbit, so the CRM was developed to provide the flux environment of 100 - 200 keV protons in the outer magnetosphere, magnetosheath, and solar wind regions of geospace. This presentation describes CRM, its role in Chandra operations, and its prediction of the ACIS CTI increase
Erratum to: Measurement of exclusive Υ photoproduction from protons in pPb collisions at s NN = 5.02 TeV (The European Physical Journal C, (2019), 79, 3, (277), 10.1140/epjc/s10052-019-6774-8)
No full textIn this article the author name Luigi Calligaris was incorrectly written as A. Calligaris. The original article has been corrected. - https://doi.org/10.1140/epjc/s10052-019-6774-8
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