CEDM constraints on modified sfermion universality and spontaneous CP violation

TL;DR

This paper explores how modifying sfermion mass universality in supersymmetry can address the CP problem, proposing a flavor structure that suppresses up quark CEDM and demonstrating a possible realization within E6 SUSY GUT models.

Contribution

It introduces a specific flavor structure to suppress up quark CEDM in modified sfermion universality scenarios, linking it to spontaneous CP violation in E6 SUSY GUT models.

Findings

Up quark CEDM can be suppressed within experimental sensitivity.

A flavor structure with real up-sector parameters is effective.

Spontaneous CP violation in E6 SUSY GUT can realize this structure.

Abstract

We discuss the supersymmetric CP problem that arises when the sfermion soft mass universality is modified. We place the 3rd generation SU(5) ten-plet sfermion masses in the weak scale in view of the naturalness. The other sfermion masses are assumed to be universal and a TeV scale in order to weaken the flavor changing neutral current processes and electric dipole moment (EDM) constraints. However this modification generically induces too large up quark chromo-EDM (CEDM) via the weak scale stop loop. In order to suppress this CEDM, we propose certain type of flavor structure where the parameters of the up-(s)quark sector are real whereas those of the down-(s)quark and the charged (s)lepton sectors are complex at the GUT scale. It is shown that, in this set up, up quark CEDM can be suppressed within the range where the current and future experiments have their sensitivity. We briefly illustrate the simple realization of these particular forms of the modified sfermion universality with real up-(s)quark sector by spontaneous CP violation in E$_6$ SUSY GUT with SU(2) flavor symmetry.