- Published on 10 August 2012
Most stringent limits ever set by ATLAS
"Supersymmetry - to be or not to be?" remains a still unanswered question - it is a traditionally difficult business to demonstrate a zero result in experimental physics - yet the ATLAS collaboration has just set new and very stringent limitations on the "viability space" of a class of new physics models incorporating gauge-mediated supersymmetry breaking.
To this end, the collaboration analyzed all channels where W or Z bosons decay into two photons and at least one neutrino while featuring a large missing transverse energy (i.e. measured in all directions perpendicular to the beam axis), these channels being particularly sensitive to new physics in these models.
No deviations from standard model predictions were observed, putting upper limits to the cross-sections for new physics and thus raising significantly the lower mass limits for postulated supersymmetric particles - e.g. to 560 GeV for the gluino mass at a 95% confidence level (see figure).
As an added "bonus" the same results also contributed to ruling out easily observable extra dimensions - the inverse value of the compactification radius of specific models with one universal extra dimension was estimated to be at least 961 GeV with a 95% confidence level.
Search for diphoton events with large missing transverse energy with 36 pb-1 of 7 TeV proton–proton collision data with the ATLAS detector
The ATLAS Collaboration, Eur. Phys. J. C (2011) 71: 1744, DOI 10.1140/epjc/s10052-011-1744-9