Hide and Seek with Massive Fields in Modulus Mediation

TL;DR

This paper investigates how massive fields in modulus mediation cancel their effects on supersymmetry breaking parameters through threshold corrections, impacting lepton flavor violation predictions.

Contribution

It demonstrates the cancellation of renormalization group effects by threshold corrections in modulus mediation with nonperturbative mass generation.

Findings

Threshold corrections cancel RG running of soft parameters.

Order reduction of lepton flavor violation is possible.

Parameter space constraints are affected by these effects.

Abstract

We study the modulus mediation of supersymmetry breaking motivated by superstring theory. We show that the renormalization group running of the soft supersymmetry breaking parameters due to the interactions of massive fields is canceled by the threshold corrections at one-loop order, if their mass is given by nonperturbative dynamics controlled by the same modulus that mediates supersymmetry breaking and a sum rule of the modular weights holds for the Yukawa couplings. As an example, we discuss order reduction of lepton flavor violation in the supersymmetric seesaw mechanism, which revives the parameter space already excluded.