RParity from the Heterotic String

Abstract

In T-duality invariant effective supergravity with gaugino condensation as the mechanism for supersymmetry breaking, there is a residual discrete symmetry that could play the role of R-parity in supersymmetric extensions of the Standard Model.

Is the universal string axion the QCD axion?

“…The conditions under which the universal axion can serve as the Peccei-Quinn axion were examined and it was found that the strong CP problem is avoided for all but the minimal SL(2, Z) version of the T-duality group of the weakly coupled heterotic string. Most compactifications have a larger T-duality group, and from a phenomenological point of view, a larger group is desirable for generating [25] the R-parity of the MSSM. Although our results were obtained using the linear supermultiplet formulation for the dilaton superfield, we expect that they can be reproduced in the chiral multiplet formulation.…”

T-Duality and the Weakly Coupled Heterotic String

“…• When combined with U (1) gauge symmetries, T-duality provides [6] a possible mechanism for R-parity or an even stronger discrete symmetry.…”

Twenty-five questions for string theorists

“…While certain R-parity violating operators can exist in isolation with O(1) coefficients, as argued above string models that do not have an intact R-parity tend to allow all such operators at various mass-dimensions in the superpotential. A more satisfying solution is to identify R-parity as a symmetry of the underlying compactification geometry -such as a remnant of a modular symmetry [43]. As the geometry of the compactified space determines the superpotential (both the tree-level and higher-genus terms) it is reasonable to ask the following question:…”