Search for strong production of supersymmetric particles in final states with missing transverse momentum and at least three b-jets at √s= 8 TeV proton-proton collisions with the ATLAS detector

This paper reports the results of a search for strong production of supersymmetric particles in 20.1 fb−1 of proton-proton collisions at a centre-of-mass energy of 8TeV using the ATLAS detector at the LHC. The search is performed separately in events with either zero or at least one high-pT lepton (electron or muon), large missing transverse momentum, high jet multiplicity and at least three jets identified as originated from the fragmentation of a b-quark. No excess is observed with respect to the Standard Model predictions. The results are interpreted in the context of several supersymmetric models involving gluinos and scalar top and bottom quarks, as well as a mSUGRA/CMSSM model. Gluino masses up to 1340 GeV are excluded, depending on the model, significantly extending the previous ATLAS limits.

Search for squarks and gluinos with the ATLAS detector in final states with jets and missing transverse momentum using √s=8 TeV proton--proton collision data

A search for squarks and gluinos in final states containing high-pT jets, missing transverse momentum and no electrons or muons is presented. The data were recorded in 2012 by the ATLAS experiment in √s = 8TeV proton-proton collisions at the Large Hadron Collider, with a total integrated luminosity of 20.3 fb−1. Results are interpreted in a variety of simplified and specific supersymmetry-breaking models assuming that R-parity is conserved and that the lightest neutralino is the lightest supersymmetric particle. An exclusion limit at the 95% confidence level on the mass of the gluino is set at 1330GeV for a simplified model incorporating only a gluino and the lightest neutralino. For a simplified model involving the strong production of first- and second-generation squarks, squark masses below 850GeV (440GeV) are excluded for a massless lightest neutralino, assuming mass degenerate (single light-flavour) squarks. In mSUGRA/CMSSM models with tan β = 30, A0 = −2m0 and μ > 0, squarks and gluinos of equal mass are excluded for masses below 1700GeV. Additional limits are set for non-universal Higgs mass models with gaugino mediation and for simplified models involving the pair production of gluinos, each decaying to a top squark and a top quark, with the top squark decaying to a charm quark and a neutralino. These limits extend the region of supersymmetric parameter space excluded by previous searches with the ATLAS detector.

Search for microscopic black holes and string balls in final states with leptons and jets with the ATLAS detector at √s = 8 TeV

A search for an excess of events with multiple high transverse momentum objects including charged leptons and jets is presented, using 20.3 fb−1 of proton-proton collision data recorded by the ATLAS detector at the Large Hadron Collider in 2012 at a centre-of-mass energy of √s = 8TeV. No excess of events beyond Standard Model expectations is observed. Using extra-dimensional models for black hole and string ball production and decay, exclusion contours are determined as a function of the mass threshold for production and the fundamental gravity scale for two, four and six extra dimensions. For six extra dimensions, mass thresholds of 4.8–6.2TeV are excluded at 95% confidence level, depending on the fundamental gravity scale and model assumptions. Upper limits on the fiducial cross-sections for non-Standard Model production of these final states are set.

Search for supersymmetry at √8=8 TeV in final states with jets and two same-sign leptons or three leptons with the ATLAS detector

A search for strongly produced supersymmetric particles is conducted using signatures involving multiple energetic jets and either two isolated leptons (e or μ) with the same electric charge, or at least three isolated leptons. The search also utilises jets originating from b-quarks, missing transverse momentum and other observables to extend its sensitivity. The analysis uses a data sample corresponding to a total integrated luminosity of 20.3 fb−1 of ps = 8TeV proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider in 2012. No deviation from the Standard Model expectation is observed. New or significantly improved exclusion limits are set on a wide variety of supersymmetric models in which the lightest squark can be of the first, second or third generations, and in which R-parity can be conserved or violated.

Search for dark matter in events with a Z boson and missing transverse momentum in pp collisions at √s=8 TeV with the ATLAS detector

search is presented for production of dark-matter particles recoiling against a leptonically decaying Z boson in 20.3 fb−1 of pp collisions at √s=8 TeV with the ATLAS detector at the Large Hadron Collider. Events with large missing transverse momentum and two oppositely charged electrons or muons consistent with the decay of a Z boson are analyzed. No excess above the Standard Model prediction is observed. Limits are set on the mass scale of the contact interaction as a function of the dark-matter particle mass using an effective field theory description of the interaction of dark matter with quarks or with Z bosons. Limits are also set on the coupling and mediator mass of a model in which the interaction is mediated by a scalar particle.

Search for direct production of charginos, neutralinos and sleptons in final states with two leptons and missing transverse momentum in pp collisions at √s = 8 TeV with the ATLAS detector

Searches for the electroweak production of charginos, neutralinos and sleptons in final states characterized by the presence of two leptons (electrons and muons) and missing transverse momentum are performed using 20.3 fb−1 of proton-proton collision data at ps = 8TeV recorded with the ATLAS experiment at the Large Hadron Collider. No significant excess beyond Standard Model expectations is observed. Limits are set on the masses of the lightest chargino, next-to-lightest neutralino and sleptons for different lightest-neutralino mass hypotheses in simplified models. Results are also interpreted in various scenarios of the phenomenological Minimal Supersymmetric Standard Model.

Search for direct top squark pair production in events with a Z boson, b-jets and missing transverse momentum in √s=8 TeV pp collisions with the ATLAS detector

A search is presented for direct top squark pair production using events with at least two leptons including a same-flavour opposite-sign pair with invariant mass consistent with the Z boson mass, jets tagged as originating from b-quarks and missing transverse momentum. The analysis is performed with proton–proton collision data at √ s = 8 TeV collected with the ATLAS detector at the LHC in 2012 corresponding to an integrated luminosity of 20.3 fb−1. No excess beyond the Standard Model expectation is observed. Interpretations of the results are provided in models based on the direct pair production of the heavier top squark state (˜t2) followed by the decay to the lighter top squark state (˜t1) via ˜t2 → Z ˜t1, and for ˜t1 pair production in natural gaugemediated supersymmetry breaking scenarios where the neutralino (˜χ 01 ) is the next-to-lightest supersymmetric particle and decays producing a Z boson and a gravitino ( ˜G ) via the ˜χ 01→ Z ˜G process.

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in sqrts = 8TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three leptons and missing transverse momentum is presented. The analysis is based on 20.3 fb−1 of √s = 8TeV proton-proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with the Standard Model expectations and limits are set in R-parity-conserving phenomenological Minimal Supersymmetric Standard Models and in simplified supersymmetric models, significantly extending previous results. For simplified supersymmetric models of direct chargino (˜χ±1 ) and next-to-lightest neutralino (˜χ02) production with decays to lightest neutralino(˜χ01) via either all three generations of sleptons, staus only, gauge bosons, or Higgs bosons, ˜χ±1 and ˜χ02 masses are excluded up to 700GeV, 380GeV, 345GeV, or 148GeV respectively, for a massless ˜χ01.

Search for Higgs boson decays to a photon and a Z boson in pp collisions at √s=7 and 8 TeV with the ATLAS detector

A search is reported for a neutral Higgs boson in the decay channel H → Zγ, Z → ℓ+ℓ− (ℓ = e, μ), using 4.5 fb−1 of pp collisions at √s = 7 TeV and 20.3 fb−1 of pp collisions at √s = 8 TeV, recorded by the ATLAS detector at the CERN Large Hadron Collider. The observed distribution of the invariantmass of the three final-state particles, mℓℓγ, is consistent with the Standard Model hypothesis in the investigated mass range of 120–150 GeV. For a Higgs boson with a mass of 125.5 GeV, the observed upper limit at the 95% confidence level is 11 times the Standard Model expectation. Upper limits are set on the cross section times branching ratio of a neutral Higgs boson with mass in the range 120–150 GeV between 0.13 and 0.5 pb for √s = 8 TeV at 95% confidence level.

In search of the "why" behind campaign professionalisation: explaining the degree and profile of campaign professionalisation by an empirical analysis of 23 Swiss cantonal election campaigns

Die Organisation und die strategische Kommunikation von Wahlkämpfen haben sich in den letzten Jahrzehnten in den meisten westeuropäischen Staaten gewandelt, so auch in der Schweiz. Die Kommunikationswissenschaft hat dafür den Begriff der „Professionalisierung“ geprägt und Eigenschaften zusammengetragen, die zu einem „professionalisierten“ Wahlkampf gehören – wie z.B. die Beauftragung von externen Expertinnen und Experten oder die direkte Ansprache von Wählerinnen und Wählern („narrowcasting“). Welche Hintergründe diese Professionalisierung aber hat und wie das Phänomen nicht nur praktisch zu beschreiben, sondern auch theoretisch zu begründen ist, wurde bisher kaum diskutiert. Hier setzt die vorliegende Dissertation an. Basierend auf einer Analyse von 23 Wahlkämpfen aus den Kantonen Aargau, Appenzell Ausserrhoden, Bern, Neuchâtel und Zürich mithilfe der Methode Fuzzy Set Qualitative Comparative Analysis (fsQCA) kommt sie zum Schluss, dass die Professionalisierung der Wahlkämpfe vor dem theoretischen Hintergrund des soziologischen Neo-Institutionalismus als Anpassung von Wahlkämpfen an sich verändernde Bedingungen, Erwartungen und Anforderungen in den wichtigsten Anspruchsgruppen oder „Umwelten“ für den Wahlkampf (Wählerinnen und Wähler, Mitglieder, Medien, andere Parteien) definiert werden kann. Daraus folgt, dass es nicht nur „die“ Professionalisierung gibt, sondern dass jeder Wahlkampf an jene Umwelten angepasst wird, wo diese Anpassung den Wahlkampfverantwortlichen am dringlichsten erscheint. Daher sollte Professionalisierung mit vier einzelnen Messinstrumenten bzw. Professionalisierungsindices – einem pro Umwelt – gemessen werden. Misst man Professionalisierung wie bisher üblich nur mit einem einzigen Messinstrument, gibt der resultierende Wert nur ein ungenaues Bild vom Grad der Professionalisierung des Wahlkampfs wieder und verschleiert, als Anpassung an welche Umwelt die Professionalisierung geschieht. Hat man ermittelt, wie professionalisiert ein Wahlkampf im Hinblick auf jede der vier relevantesten Umwelten ist, können dann auch zuverlässiger die Gründe analysiert werden, die zur jeweiligen Professionalisierung geführt haben. Die empirische Analyse der kantonalen Wahlkämpfe bestätigte, dass hinter der Professionalisierung in Bezug auf jede der vier Umwelten auch tatsächlich unterschiedliche Gründe stecken. Wahlkämpfe werden in Bezug auf die Ansprache der Wähler angepasst („professionalisiert“), wenn sie in urbanen Kontexten stattfinden. Den Wahlkampf im Hinblick auf die Mitglieder zu professionalisieren ist besonders wichtig, wenn die Konkurrenz zwischen den Parteien gross ist oder wenn eine Ansprache der Gesamtwählerschaft für eine Partei wenig gewinnbringend erscheint. Die Professionalisierung des Wahlkampfes in Bezug auf die Medien erfolgt dann, wenn er eine grosse, regional stark verteilte oder aber eine urbane Wählerschaft ansprechen muss. Für die Professionalisierung der Wahlkämpfe gegenüber anderen Parteien kann kein aussagekräftiger Schluss gezogen werden, da nur wenige der untersuchten Kantonalparteien ihre Wahlkämpfe überhaupt im Hinblick auf andere Parteien professionalisierten, indem sie die gegnerischen Wahlkämpfe beobachteten und den eigenen wenn nötig entsprechend anpassten.