Discrete gauge symmetries and proton stability in the U(1)'-extended MSSM

Understand

The Minimal Supersymmetric Standard Model (MSSM) with conserved R-parity suffers from several fine-tuning problems, e.g.

• the mu-problem and the problem of proton decay through higher dimension operators.
• Both of these problems can be avoided by replacing R-parity with a non-anomalous U(1)' gauge symmetry which is broken at the TeV scale.
• The new gauge symmetry does not necessarily forbid all renormalizable R-parity violating interactions among the MSSM fields, and may allow for either lepton number or baryon number violation at the renormalizable level.