Wednesday’s CMS result finding no black holes in early LHC data has led to internet headlines such as String Theory Fails First Major Experimental Test (for what this really means, see here). At a talk today at CERN, yet another impressive new CMS result was announced, this one causing even more trouble for string theory (if you believe in purported LHC tests of string theory, that is…).
Back in 1997, Physics Today published an article by Gordon Kane with the title String Theory is Testable, Even Supertestable. It included as Figure 2 a detailed spectrum which was supposed to show the sort of thing that string theory predicts. Tevatron results have already caused trouble for many of these mass predictions. For example, gluinos are supposed to have a mass of 250 GeV, but the PDG lists a lower bound (under various assumptions) of 308 GeV. At CERN today, the CMS talk in the end-of-year LHC jamboree has a slide labeled “First SUSY Result at the LHC!”, showing dramatically larger exclusion ranges for possible squark and gluino masses. Over much of the relevant range, gluino masses are now excluded all the way up to 650 GeV. It looks like string theory has failed the “supertest”.
If you believe that string theory “predicts” low-energy supersymmetry, this is a serious failure. Completely independently of string theory, it’s a discouraging result for low-energy supersymmetry in general. The LHC has just dashed hopes that, at least for strongly-interacting particles, supersymmetry would show up just beyond the energy range accessible at the Tevatron.