High Energy Physics and Computational Science

  Re-analysing LHC Run 2 data with cutting-edge analysis techniques allowed CMS physicists to address an old discrepancy. Supersymmetry (SUSY) is an exciting and beautiful theory that answers some of the open questions in particle physics. It predicts that all known particles have a “superpartner” with somewhat different properties. For example, the heaviest quark of the Standard Model, the top quark, would have a superpartner called the top squark, or simply the “stop”. In 2021 the CMS collaboration analysed the entire set of collision data collected from 2016 to 2018 and found features suggesting that it might contain stop particles. In that case, “might” meant that there was less than 5% chance that data containing only known particles could look like what was observed. Instead of waiting many years to collect more data with the hope of reproducing this behaviour, the CMS collaboration decided to reanalyse the same data with upgraded analysis techniques. The new analysis loo...

  Physicists from the ATLAS Collaboration at CERN’s Large Hadron Collider (LHC) have released the most sensitive search for di-Higgs production and self-coupling yet, achieved by combining five di-Higgs studies of LHC Run 2 data. Remember how difficult it was to find one Higgs boson? Try finding two at the same place at the same time. Known as di-Higgs production, this fascinating process can tell scientists about the Higgs boson self-interaction. By studying it, physicists can measure the strength of the Higgs boson’s self-coupling, which is a fundamental aspect of the Standard Model that connects the Higgs mechanism and the stability of our Universe. Searching for di-Higgs production is an especially challenging task. It’s a very rare process, about 1,000 times rarer than the production of a single Higgs boson. During the LHC Run 2, only a few thousand di-Higgs events are expected to have been produced in ATLAS , compared with the 40 million collisions that happened every seco...