The LHC Higgs Boson Discovery: Updated implications for Finite Unified Theories and the SUSY breaking scale

Abstract

Finite Unified Theories (FUTs) are N = 1 supersymmetric Grand Unified Theories which can be made finite to all orders in perturbation theory, based on the principle of reduction of couplings. The latter consists in searching for renormalization group invariant relations among parameters of a renormalizable theory holding to all orders in perturbation theory. FUTs have proven very successful so far. In particular, they predicted the top quark mass one and half years before its experimental discovery, while around five years before the Higgs boson discovery a particular FUT was predicting the light Higgs boson in the mass range ~ 121 - 126 GeV, in striking agreement with the discovery at LHC. Here we review the basic properties of the supersymmetric theories and in particular finite theories resulting from the application of the method of reduction of couplings in their dimensionless and dimensionful sectors. Then we analyse the phenomenologically favoured FUT, based on SU(5). This particular FUT leads to a finiteness constrained version of the MSSM, which naturally predicts a relatively heavy spectrum with coloured supersymmetric particles above 2.7 TeV, consistent with the non-observation of those particles at the LHC. The electroweak supersymmetric spectrum starts below 1 TeV and large parts of the allowed spectrum of the lighter might be accessible at CLIC. The FCC-hh will be able to fully test the predicted spectrum.