Search for $Z'$, vacuum (in)stability and hints of high-energy   structures
  We study the high-energy behaviour of a class of anomaly-free abelian extensions of the Standard Model. We focus on the interplay among the phenomenological characterisation of the model and the use of precise renormalisation group methods. Using as boundary conditions regions of the parameter space at the verge of current LHC probe, interesting unification patterns emerge linked to thresholds belonging to a SO(10) grand unification theory (GUT). We stress how the evolution of the mixing between the two abelian factors may provide a valuable tool to address the candidate high-energy embedding. The emerging unification scenarios are then challenged to be perturbative and to allow for a stable vacuum. 
Elena Accomando, Claudio Coriano, Luigi Delle Rose, Juri Fiaschi,   Carlo Marzo, Stefano Moretti
hep-ph