Low Scale Unification of Gauge Interactions
  We investigate the possibility to realize the unification of the Standard Model gauge interactions at the low scale in four dimensions. We find that the fields needed to define a minimal theory where baryon and lepton numbers are local symmetries, allow for unification at the low scale in agreement with experiments. In these scenarios the proton is stable and we briefly discuss the implications for cosmology. 
Pavel Fileviez Perez, Sebastian Ohmer
hep-ph hep-th