Oxford students lead first complete supersymmetry searches at ATLAS

18 September 2013

University of Oxford graduate students have led the first two papers for Supersymmetry using the full data-set from the ATLAS experiment at the CERN Large Hadron Collider.

The first analysis published was led by Oxford second-year grad student Mireia Crispin Ortuzar. The paper seeks new weakly-interacting particles which might explain the astronomical dark matter in events with large numbers of jets of visible particles. The dark matter candidate particles would betray their presence from apparent momentum imbalance. The analysis uses an innovative background-determination method which was proposed by former Oxford graduate student Chris Young, who has recently completed his D.Phil. and joined CERN as a fellow.

Region of sbottom squark and neutralino masses excluded by the analysis

Alexandru Dafinca was the main researcher behind the second ATLAS supersymmetry search analysis. Alex is a third year grad student within the Oxford SUSY group, and has worked both on detector performance studies for the Semiconductor Tracker, and on several physics analyses. His most recent paper is a search for the supersymmetric partner of the bottom quark. The so-called "scalar bottom" or "sbottom" is one of the most eagerly-sought particles at the LHC, since the third generation particles seem to play an important role in physics at the electroweak scale. Alex's analysis provides the most sensitive search to date.

A third analysis, led by Oxford postdoctoral researcher Andree Robichaud Veronneau has just been released as a conference note for the SUSY-2013 conference. That analysis is the first at the LHC to search for supersymmetric particles decaying into Higgs bosons.

The three analyses each show good agreement with the Standard Model predictions, providing significantly improved limits on the possible masses of supersymmetric particles, and constraints on some theoretical models.

The group has several further searches in progress, based on the 2011-2012 ATLAS data. It is also at the forefront of preparing for the high-energy run of 2015, and for future LHC luminosity and energy upgrades.

More information about the Oxford SUSY group can be found on the group web pages. The group is led by Dr Alan Barr.