Research
Collider Physics
The last piece in the puzzle, called听the Standard Model of Particle Physics (SM), was put in place in 2012听with CERN's听discovery of the Higgs boson. 听This happened听more than 50 years after its prediction. Is this听triumph of the SM听the end or just the听begining听of an even bigger puzzle where the missing听pieces are still in the dark?
Around 1900 a great physicist said:听There is nothing new to be discovered in physics now. All that remains is more and more precise measurement.听And he could not have been more听wrong: just a few years later both听Quantum Mechanics and Relativity were discovered. Will nature be so kind to听bestow听another such听surprise on us?
The role of Dark Matter and gravity in the quantum world could be听key elements in this quest. The LHC allows us to shine light on the mysteries of the quantum world听and test hypotheses of听physics Beyond the Standard Model (BSM),听such as Supersymmetry or the existence of Extra Spatial Dimensions. With a bit of luck we might see hints of what could be described as听an even bigger puzzle of which the SM is just the first piece.
The ATLAS group of the DPNC is heavily involved in all听areas of the experiment:
- Hardware:听construction of a new silicon tracker听for HL-LHC (tracker layout, mechanics, novel HV-CMOS听monolithic silicon detectors, Level-1 track trigger)
- Data analysis: searches for physics beyond the SM with focus on high-pT objects including jets,听boosted objects, b-jets, and听MET
- Novel techniques for data reconstruction: b-tagging,听boosted object-tagging, particle flow
- Machine Learning:听applications to open HEP听questions听such as CPU-limitation in Run-4 tracking and fast calorimeter shower simulation, improvements to听b-tagging and boosted object-tagging
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The UNIGE ATLAS group has a large track record of past contributions:
- Hardware:听construction of the current ATLAS detector:听strip tracker, trigger/DAQ, calorimeter readout electronics, SC toroid coil casings, and the IBL (Inner Barrel Layer)
- Data analysis: Higgs discovery, SM measurements, searches for physics beyond the SM
- Major responsbilities held by UniGe ATLAS members include: technical coordination; silicon tracker coordination (SCT + IBL); trigger/DAQ construction, operation and coordination; publications; analysis coordination; detector alignment; and detector upgrade.
A short history of the LHC era:
the LHC started producing proton-proton collisions at the centre of the ATLAS experiment in 2010 at a centre-of-mass energy of 7 TeV, increasing this value to 8 TeV in 2012, leading to the Higgs-boson discovery. After a two-year shutdown the energy was increased to 13 TeV. Since 2015 the LHC is running with this energy, pushing the search for BSM physics to higher and higher masses, lower cross sections and larger lifetime. The multi-purpose nature of the ATLAS detector allows this search听program to grow steadily in breadth and depth. In addition the Higgs boson and its properties are studied in great detail as the luminosity increases, as are other SM properties.
Looking ahead, by the end of 2023 a ten-fold increase in the听luminosity of the听13 TeV data set is expected as compared to the end of 2016. After another shutdown where both ATLAS and the LHC are upgraded, the so-called High-Luminosity LHC phase starts in 2026 until 2035, in which the luminosity will be increased by another order of magnitude, both pushing the sensitivity to direct new physics discovery and precision Higgs and SM measurements to unprecedented areas.