Despite advances in multivariate visualisations and computer graphics, allowing for effective implementations, most particle physics analyses still rely on conventional data visualisations. The currently available software implementing these techniques has been found to be inadequate for use with the large volume of multivariate data produced from modern particle physics experiments. After a design and development period, a novel piece of software, DataViewer, was produced. DataViewer was used as part of a physics analysis at the CMS experiment, searching for an associated Higgs decaying through a dark sector into collimated groups of electrons, called Electron Jets. Observation of such a signature could explain astrophysical anomalies found by numerous telescopes. The full 2011 dataset, equivalent to an integrated luminosity of 4.83 fb^(-1) at a centre of mass energy of sqrt(s) = 7 TeV, recorded by the experiment was analysed. DataViewer was found to be extremely powerful in rapidly identifying interesting attributes of the signature which could then be exploited in the analysis. Additionally it could be used for cross checking other complex techniques, including multivariate classifiers. No evidence was found for the production of a Higgs boson in association with a Z boson, where the Higgs subsequently decays to Electron Jets. Upper limits on the production of benchmark models were set at the 95% Confidence Level.

Hadronic collisions at the LHC at CERN probe particle interactions at the highest energy scale of any experiment to date. We present a research program measuring Rjet = &sigmaWBR(W&rarr&mu&nu) / (&sigmaZBR(Z&rarr&mu&mu)) as a function of a number of hadronic variables. The measurements are performed with the ATLAS detector at the LHC, using the 2011 data set, consisting of 4.64 fb-1 of pp collisions at a center of mass energy of 7 TeV. This measurement is a robust way to test the Standard Model and the modeling of perturbative QCD, and is sensitive to a wide variety of possible new physics in events with high jet ET, including some variations of Supersymmetry. By taking the ratio of W/Z production, a large number of systematic uncertainties cancel, including those associated with luminosity, jet energy scale and resolution, and many theoretical uncertainties. The measurement of Rjet is performed as a function of the pT and rapidity of the 1st-4th leading jet, ST, HT, and a number of dijet variables, including invariant mass and angular separations. The measurements are compared with NLO theoretical predictions from Blackhat+Sherpa, as well as using leading order simulations from Alpgen and Sherpa. Over most of the kinematic phase-space, there is good agreement between the data and theoretical predictions. There is a significant deviation for exactly one selected jet above 30 GeV, where Blackhat+Sherpa over-estimates the ratio Rjet by 12%.

A measurement of the mass of the top quark is presented, using top-antitop pair (t-tbar) candidate events for the lepton+jets decay channel. The measurement makes use of Tevatron proton-antiproton collision data at centre-of-mass energy 1.96 TeV, collected at the CDF detector. The top quark mass is measured by employing an unbinned maximum likelihood method where the event probability density functions are calculated using signal (t-tbar) and background (W+jets) matrix elements, as well as a set of parameterised jet-to-parton mapping functions. The likelihood function is maximised with respect to the top quark mass, the fraction of signal events, and a correction to the jet energy scale (JES) of the calorimeter jets. The simultaneous measurement of the JES correction (ΔJES) provides an in situ jet energy calibration based on the known mass of the hadronically decaying W boson. Using 578 lepton+jets candidate events corresponding to 3.2 inverse femtobarns of integrated luminosity, the top quark mass is measured to be 172.4 ± 1.4(stat+ΔJES) ± 1.3(syst) GeV/c², one of the most precise single measurements to date.