Split extended supersymmetry from intersecting branes

TL;DR

This paper explores string theory models with intersecting D-branes that produce split supersymmetry, showing how small deformations lead to hierarchical mass scales for gauginos and Higgsinos, with potential implications for unification.

Contribution

It provides explicit string amplitude calculations demonstrating hierarchical gaugino and Higgsino masses in intersecting brane models with split supersymmetry.

Findings

Gauginos acquire Dirac masses suppressed by the string scale.

Higgsino mass parameter behaves as the fourth power of the deformation scale.

An explicit string model with Standard Model features and gauge unification is constructed.

Abstract

We study string realizations of split extended supersymmetry, recently proposed in hep-ph/0507192. Supersymmetry is broken by small ($\epsilon $) deformations of intersection angles of $D$-branes giving tree-level masses of order $m_0^2\sim \epsilon M_s^2$, where $M_s$ is the string scale, to localized scalars. We show through an explicit one-loop string amplitude computation that gauginos acquire hierarchically smaller Dirac masses $m_{1/2}^D \sim m_0^2/M_s$. We also evaluate the one-loop Higgsino mass, $\mu$, and show that, in the absence of tree-level contributions, it behaves as $\mu\sim m_0^4/M_s^3$. Finally we discuss an alternative suppression of scales using large extra dimensions. The latter is illustrated, for the case where the gauge bosons appear in N=4 representations, by an explicit string model with Standard Model gauge group, three generations of quarks and leptons and gauge coupling unification.