The Standard Model (SM) of particle physics is an extremely successful theory which several times over the past decades has predicted the existence of new particles or phenomena, which later have been discovered in experiments. The SM also explains, to unprecedented precision, many experimental observations. However, it has some clear known shortcomings, one of them being that it does not contain a viable dark matter (DM) candidate. This suggests that there must be a more complete theory beyond the SM.
One such possible extension of the SM is Supersymmetry (SUSY). Symmetries play a crucial role in physics and SUSY relates integer spin particles (bosons) and half-integer spin particles (fermions). It allows unification of the electroweak and strong interactions, proposes DM candidates, and predicts five Higgs bosons (3 neutral and 2 charged ones).
At the end of June 2026 LHC started on a 4 years long shutdown, to be used for upgrades and maintenance of the accelerator and detector complex. In 2030 a new phase of LHC will start, known as the High Luminosity LHC (HL-LHC). The HL-LHC will not represent a big leap in energy from the current, but the amount of data will increase by a factor of ten! This will enable searches for SUSY and DM in the more challenging regions where SUSY either behave very different from what we have assumed so far, are very unlikely to be produced or look very much like all the other things which are copiously produced in proton-proton collisions from known SM processes at the LHC.
There are several means of searching for Supersymmetry at the ATLAS experiment. The ATLAS group in the High Energy Physics (HEP) section has a particular expertise in searching for SUSY where the initial SUSY particles are produced through electroweak processes. These production mechanisms typically have smaller probabilities compared with e.g productions through the strong interaction. However, a decade of negative results in searches for the superpartners of gluons and quarks (gluinos and squarks) have put these almost out of reach at the LHC (and HL-LHC). Thus electroweak production of SUSY represents a viable hope, with a large uncovered and available phase space yet to be explored.
We offer several master topics searching for electroweak production of charginos, neutralinos and sleptons that decays to various SM particles and subsequently to the LSP, the perfect dark matter candidate. The HEP section is particularly interested in searches with 2 or 3 leptons together with missing transverse momentum, a quantity inferred from the measured objects and momentum-energy conservation, and used to indicate the production of an undetected particle (like the LSP).
The MSc topics can either be related to development of new techniques to efficiently separate a tiny signal from a larger background of events from SM processes using e.g. artificial intelligence and machine learning. We also offer more theoretical topics on phenomenological aspects of SUSY trying to identify new and uncovered SUSY models and scenarios, which could be searched for at the LHC in the future. Regardless of the specificity of the model or topic under study the MSc project will contain several common milestones:
M1: Study which SUSY models can be explored at the LHC and/or identify uncovered regions that could be interesting to study further.
M2: Identify which particles, of the ones we can measure in ATLAS, will be important for your study.
M3: Identify the backgrounds, i.e. known processes that will produce the same particles as your SUSY model.
M4: By using provided simulations of signal and background, develop novel analysis techniques/ideas to efficiently separate signal from background.
M5: Make sure the simulated background and real data recorded by ATLAS fit well in some dedicated control regions to ensure that we can trust the analysis.
M6: Apply your techniques/ideas on the real data in regions where you expect signals to be present.
M7: Do a statistical analysis of your results to compare with other methods and possibly prove or exclude the existence of new particles.
Through this process there are ample possibilities for tailoring the studies to the interest of the student. In any case you will be part of an analysis group at CERN with people from both the HEP section at UiO and other parts of the world.
Courses relevant from the bachelor's degree:
Recommended courses for theoretical curriculum in the master's programme: