21 February 2011

SUSY Cornered

Large Hadron Collider results have narrowed the possible mass range for supersymmetric particles with QCD color charge (squarks and gluinos) to an increasingly narrow range (about half of the pre-LHC range), in discoveries recounted at R├ęsonaances, in two recent blog posts (here and here) particularly in the version known as mSUGRA (minimal supergravity).

mSUGRA is often seen as one of the best theoretically explored possible low energy limits of string theory and is a minimal extension of the MSSM (minimal supersymmetric model), the simpliest version of supersymmetry (SUSY), that incorporates gravity.

In the same way, LHC has very much narrowed the potential mass range of the hypothesized Higgs boson, although two and three sigma anomolies in the mass range where the Higgs boson mass should be give researchers stronger hope that it will be found.

Of course, if you find a squark or gluino in the itty bitty bit of the parameter space that is left, this becomes a matter of mere historical importance. And, there are lots of ways that one can modify SUSY theories to make them fit the data. But, suffice it to say that SUSY is proving very elusive experimentally.

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