Thesis and job opportunities

The STYX experiment is part of the Master lab. course. It uses straw-tube detectors from the ZEUS experiment to measure the properties of cosmic rays. These are the same basic detector elements as those used in the ATLAS TRT. The detector also allows students to become familiar with operating many aspects of a particle-physics detector from testing to calibration and track reconstruction. New ideas for the tracking include the use of a Hough transformation for track finding. Studies and improvements to the setup of the experiment include implementing a new readout board, which would allow measurements over a larger area, a redesign of the trigger, powering and readout connections and improvements in the calibration tools.

The particle flow algorithm in ATLAS has been developed to improve the energy resolution of hadronic objects (jets, taus, missing transverse energy), which are a key ingredient for many physics analyses. The idea of the particle flow algorithm is to replace the energy deposited by the charged particles in the calorimeters by the momentum determined by the tracking system; exploiting the fact that the tracker has better resolution than the calorimeter for low transverse momentum. During Run 3 it is planned to extend the current algorithm to include electrons, photons and mouns as particle flwo objects.

Machine learning tools are finding more and more applications in particle physics analyses. Our group has many years of experience in using such techniques and has built up a framework that is used in many different analyses. The framework enables students to get started rapidly in using such tools. Areas where theses could be written include the development and comparison of different machine-learning techniques in ATLAS single top physics analyses; electron and photon identifcation; tau lepton mis-identification (fakes).
Measurement of the single top quark production in association with heavy bosons:Single top-quark production has been measured for the first time by the Tevatron experiments CDF and D0. The LHC experiments ATLAS and CMS were able to observe the production with much less data, thanks to the larger cross-section at higher energies. The coupling between a top quark and the Higgs boson is a key measurement that is planned to be made with the data from LHC Run 2 and/or 3. If the Higgs boson coupling is exactly as predicted in the Standard Model, the production of a Higgs boson in association with a single top quark is expected to be very small. However, non-standard couplings could enhance the cross-section significantly. As a first step towards a measurement of tH production, tZ production is being studied. Such a measurement allows the techniques to be developed and optimised.

Single top-quark production has been measured for the first time by the Tevatron experiments CDF and D0. The LHC experiments ATLAS and CMS were able to observe the production with much less data, thanks to the larger cross-section at higher energies. The coupling between a top quark and the Higgs boson is a key measurement that is planned to be made with the data from LHC Run 2 and/or 3. If the Higgs boson coupling is exactly as predicted in the Standard Model, the production of a Higgs boson in association with a single top quark is expected to be very small. However, non-standard couplings could enhance the cross-section significantly. As a first step towards a measurement of tH production, tZ production is being studied. Such a measurement allows the techniques to be developed and optimised.