Supersymmetry
One of the current theories suggested to extend the particle Standard Model, which, in particular, predicts twice the number of fundamental particles through a new "supersymmetry" – hence the name of this model family, often abbreviated as "SUSY". This additional property solves some of the Standard Model theoretical "gaps", especially regarding the Higgs boson and the question of particles' masses. Today SUSY still remains a mere hypothesis which the LHC tries to confirm or infirm.