New Standard Model Vacua from Intersecting Branes

TL;DR

This paper constructs non-supersymmetric intersecting D6-brane models that replicate the Standard Model spectrum, including right-handed neutrinos, with stable proton and specific U(1) gauge symmetries, advancing string phenomenology.

Contribution

It introduces new intersecting D6-brane vacua with Standard Model features, including anomaly cancellation and neutrino masses, in a non-supersymmetric framework.

Findings

Standard Model spectrum with right-handed neutrinos achieved

Proton stability via gauged baryon number

Prediction of a single supersymmetric particle, the _R superpartner

Abstract

We construct new D6-brane model vacua (non-supersymmetric) that have at low energy exactly the standard model spectrum (with right handed neutrinos). The minimal version of these models requires five stacks of branes. and the construction is based on D6-branes intersecting at angles in $D = 4$ type toroidal orientifolds of type I strings. Three U(1)'s become massive through their couplings to RR couplings and from the two surviving anomaly free U(1)'s, one is the standard model hypercharge generator while the extra anomaly free U(1) could be broken from its non-zero couplings to RR fields and also by triggering a vev to previously massive particles. We suggest that extra massless U(1)'s should be broken by requiring some intersection to respect N=1 supersymmetry thus supporting the appearance of massless charged singlets at the supersymmetric intersection. Proton is stable as baryon number is gauged and its anomalies are cancelled through a generalized Green-Schwarz mechanism. Neutrinos are of Dirac type with small masses, as in the four stack standard models of hep-th/0105155, as a result of the existence of a similar PQ like-symmetry. The models are unique in the sense that they predict the existence of only one supersymmetric particle, the superpartner of $\nu_R$.