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ATLAS Supersymmetry Searches and More at SUSY 2012 in Beijing
13 August 2012

The 20th International Conference on Supersymmetry and Unification of Fundamental Interactions (SUSY 2012) is taking place in Beijing, China on 13 -18 August 2012. SUSY is the theory which, if confirmed by experiment, will be the high energy extension of the Standard Model (SM). In SUSY, every particle should have a massive "shadow" particle or super-partner. Experimentalists have been looking for years for proof of the existence of these SUSY particles or sparticles.

This year's annual conference not only included reports on SUSY searches but was much broader with sessions on the Standard Model, Higgs Searches, Physics Beyond the SM and Exotics, Neutrinos, Dark Matter and Cosmology. The six day long conference included both plenary and parallel sessions every day. ATLAS presented a large number of results in almost all sessions. In total it presented 29 conference announcements spanning from SUSY searches, detailed analyses of the recently discovered Higgs particle, searches for charged Higgs particles, exotic searches, long-lived particle searches but also precision measurement in the SM sector.

For the SUSY part -- mainly within the Minimal Super-Symmetric Model (MSSM) -- both inclusive searches, where one looks for a number of jets plus missing transverse momentum, as well as dedicated searches with final states including multileptons, b-jets, etc. were presented. New limits in the MSSM plane were also shown. A number of new limits on the masses of the squark and the gluino were presented, together with indirect searches for the LSP (lightest supersymmetric particle - a candidate for the so-called dark matter, the approximately 80% of the total mass of the universe that is not visible to astronomers as luminous matter). In addition, direct searches for the partners of the 3rd generation SM quarks, the sbottom and stop, were on the conference programme.

95% Confidence Level exclusion limits for specific Supersymmetry models (MSUGRA/CMSSM) under specific constraints (see details here). One of the ATLAS talks in SUSY 2012 presented the results of a search for proposed supersymmetric particles called squarks and gluinos in events containing jets and missing transverse momentum. Although the particles were not found, such measurements exclude certain regions, giving us important clues on where to look next. ATLAS measurements have been able to exclude most of the plane allowed by this particular model (CMSSM/MSUGRA) which is one of the most popular SUSY models.


Regions eliminated to 95% confidence in ATLAS SUSY searches. In these models, the third generation Standard Model top and proposed supersymmetric stop quarks are light and copiously produced via pair gluino decays, whereas the Lightest Supersymmetric Particle (LSP) is thought to be stable.

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