Evolution of the Inverse Fine Structure beyond the Standard Model

Abstract

In this dissertation, the one-loop renormalization group equations for the gauge couplings in five and six dimensional models as well as 5D Minimal Super-symmetric Standard Model were derived. We considered different localization of matter fields that is, all fields propagate in the full space-time (bulk case), or some of the fields restricted in the brane (brane case). We studied the evolution of the inverse fine structure constantsα^(-1), which is linked to the gauge couplings constant. We found that the three inverse fine structure constants approximately unified at some high-energy scale at E=〖10〗^4.31 GeV and 〖E=10〗^3.60 GeV in five and six dimensional models respectively. We also compare the 5D SM result with 6D SM results, and we found that there is only one different which is, the running in 6D SM is faster than 5D SM. Furthermore, a successful unification of the three gauge couplings was achieved in 5D MSSM plus additional fields in both scenarios. We found a precise unification is achieved at energy scaleE=〖10〗^4.48 GeV.