Non-generic Couplings in Supersymmetric Standard Models

Understand

We study two phases of a heterotic standard model, obtained from a Calabi-Yau compactification of the E8xE8 heterotic string, in the context of the associated four-dimensional effective theories.

• In the first phase we have a standard model gauge group, an MSSM spectrum, four additional U(1) symmetries and singlet fields.
• In the second phase, obtained from the first by continuing along the singlet directions, three of the additional U(1) symmetries are spontaneously broken and the remaining one is a B-L symmetry.
• In this second phase, dimension five operators inducing proton decay are consistent with all symmetries and as such, they are expected to be present.