Sequestered String Models imply Split Supersymmetry

TL;DR

This paper explores sequestered string models that naturally lead to split supersymmetry, analyzing stability and flavor constraints, and identifying viable parameter ranges for soft-terms to avoid cosmological and phenomenological issues.

Contribution

It provides a detailed analysis of stability and flavor constraints in sequestered string models, proposing that they can realize split supersymmetry with specific mass spectra.

Findings

Split supersymmetry spectrum with TeV gauginos and 10^7 GeV sfermions is viable.

Flavor constraints are satisfied if soft-terms are sufficiently heavy.

Universal soft-term scenarios face stability issues due to charge and color breaking vacua.

Abstract

Sequestering is a promising mechanism in 4D string models to reconcile high-scale inflation with low-energy supersymmetry. In this scenario the MSSM lives on branes at singularities and it is sequestered from the sources of supersymmetry breaking in the bulk. The soft-terms are suppressed with respect to the gravitino mass so that all moduli are heavy enough to avoid any cosmological moduli problem. In this paper we study stability bounds and flavour constraints on sequestered string models, finding that they can be satisfied if the soft-terms give rise to a mass spectrum typical of split supersymmetry with TeV-scale gauginos and sfermions around $10^7$ GeV. When instead scalar and gaugino masses are of the same order of magnitude, large flavour changing neutral currents can be avoided only by pushing the soft-terms above $10^6$ GeV. However this scenario is in tension with stability bounds due to the presence of charge and colour breaking vacua which could be populated in the early universe, and the possible emergence of directions along which the potential is unbounded from below.