Connection between proton decay suppression and seesaw mechanism in   supersymmetric SO(10) models
  We propose a mechanism to suppress proton decay induced by dimension-5 operators in a supersymmetric SO(10) model. Proton lifetime is directly connected with the intermediate vacuum expectation value which is responsible for the seesaw mechanism. The model shows many consistencies with the present theoretical results such as the components of the two Higgs doublets in the minimal supersymmetric standard model. 
Lipei Du, Xiaojia Li and Da-Xin Zhang
hep-ph