Towards Realistic String Vacua From Branes At Singularities

TL;DR

This paper advances the construction of realistic string models with D-branes at singularities, integrating moduli stabilization and low-scale supersymmetry breaking, and explores their phenomenological implications including potential explanations for experimental anomalies.

Contribution

It introduces explicit models with realistic matter content and family symmetries within the LARGE volume framework, and analyzes their soft supersymmetry breaking and physical predictions.

Findings

Models with three families and Standard Model gauge symmetries without exotics.

Family symmetries from singularity structures influence Yukawa couplings.

Potential explanation for the Tevatron ghost muon anomaly via a new hyperweak force.

Abstract

We report on progress towards constructing string models incorporating both realistic D-brane matter content and moduli stabilisation with dynamical low-scale supersymmetry breaking. The general framework is that of local D-brane models embedded into the LARGE volume approach to moduli stabilisation. We review quiver theories on del Pezzo $n$ ($dP_n$) singularities including both D3 and D7 branes. We provide supersymmetric examples with three quark/lepton families and the gauge symmetries of the Standard, Left-Right Symmetric, Pati-Salam and Trinification models, without unwanted chiral exotics. We describe how the singularity structure leads to family symmetries governing the Yukawa couplings which may give mass hierarchies among the different generations. We outline how these models can be embedded into compact Calabi-Yau compactifications with LARGE volume moduli stabilisation, and state the minimal conditions for this to be possible. We study the general structure of soft supersymmetry breaking. At the singularity all leading order contributions to the soft terms (both gravity- and anomaly-mediation) vanish. We enumerate subleading contributions and estimate their magnitude. We also describe model-independent physical implications of this scenario. These include the masses of anomalous and non-anomalous U(1)'s and the generic existence of a new hyperweak force under which leptons and/or quarks could be charged. We propose that such a gauge boson could be responsible for the ghost muon anomaly recently found at the Tevatron's CDF detector.