ATLAS
At the turn of 1992 and 1993, the cooperation of the Comenius University in Bratislava with the European Organization for Nuclear Research - CERN began. The structure of matter, which forms the world around us, is being investigated at the Large Hadron Collider LHC. We study the particles created mainly during proton-proton collisions at the ATLAS experiment.
The ATLAS experiment is a multi-purpose particle detector focused on studying mainly deep-inelastic particle interactions. The aim of these studies is to investigate the structure of matter at the level below 10-20 m – to find its basic constituents and the forces acting between them. It is actually a gigantic microscope with a resolution of ≤ 10-20 m.
In our group, the we focus mainly on the following topics:
Top quark physics
Top quark is the most heaviest quark with mass of around 172,5 GeV. Its mean life time is shorter than time needed for hadronization, therefore, we can study top quark only using its decay product. Several studies have been publish:
- Measurement of the top quark charge:
- Measurement of the top quark decay width:
- Analysis of 8 TeV data: Eur. Phys. J. C(2018) 78:129 (arXiv:1709.04207)
- Analysis of 13 TeV data: conf. note: ATLAS-CONF-2019-038
- Study of boosted objects initiated by top-quarks and W-bosons:
- Production of top quark pair associated with Z boson:
- Energy asymmetry in production of top quark pair associated with additional jet:
- Charge asymmetry in top quark pair production:
- conf. note ATLAS-CONF-2019-026,
- JHEP 08 (2023) 077 (arXiv:2208.12095)
Soft QCD
We mainly study the Bose-Einstein correlations of the system of two bosons (specifically, two pions). The correlations are investigated in multiparticle events created during proton-proton collisions. The aim of the study is to determine the size of the hadronization region as a dependence on the number of created particles. The results of the analyzes have been published:
For more details about the individual analysis, go >> here.
Working in the ATLAS collaboration also requires involvement in hardware tasks:
- Our group is involved in the team working on the hadronic calorimeter (TileCal). Our basic task is to control quality of the recorded data, where the post of DQ coordinator belongs to our colleague. We have developed, modified and continue to maintain the software for TileCal.
- As part of the modernization of the TileCal detector, we have built a laboratory for photomultiplier tests as well as a basic setup for their testing. The photomultipliers tested in our laboratory will become a part of the TileCal detector. They will be installed during the planned technical break of the LHC, in 2026-2028.
- Calculations for analyzes are so demanding that it is often necessary to use computer farms. We also operate one such PC-farm, which is part of the WLCG, grid system, at the Faculty of Mathematics, Physics and Informatics of the Comenius University in Bratislava..