String model building at low string scale: Towards the standard model

Abstract

We consider string model building in scenarios in which the fundamental string scale is low compared to the four-dimensional Planck scale. We present a consistent string theory model which gives a conservative extension of the Standard Model, consisting of a D3-brane at a simple orbifold singularity. We envision this, for example, as a local singularity within a warped compactification. We describe some of the phenomenology of this model. There are natural hierarchies in the fermion spectrum, which is only realistic for a string scale in the multi-TeV range.