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Electric Dipole Moments in Split Supersymmetry

G. F. Giudice, A. Romanino

TL;DR

This work analyzes neutron and electron electric dipole moments in Split Supersymmetry with heavy scalars, where EDMs arise at two loops via the gaugino–Higgsino sector. The authors derive complete analytic expressions for the three two-loop contributions from $\gamma H$, $ZH$, and $WW$ exchanges, introducing a crucial $ZH$ term that is particularly relevant for the neutron EDM, and they correct the QCD running of quark EDMs. Through a heavy-chargino expansion and a numerical scan in a GUT-inspired parameter space, they show that EDMs can be within next-generation experimental reach and that the electron–neutron EDM correlation provides a stringent test of Split SUSY, albeit with residual hadronic and parameter-space uncertainties. The work clarifies the relative importance of the three diagrams and connects the observable EDMs to CP-violating invariants in the gaugino–Higgsino sector, offering a concrete phenomenological probe of Split SUSY CP violation.

Abstract

We perform a quantitative study of the neutron and electron electric dipole moments (EDM) in Supersymmetry, in the limit of heavy scalars. The leading contributions arise at two loops. We give the complete analytic result, including a new contribution associated with Z-Higgs exchange, which plays an important and often leading role in the neutron EDM. The predictions for the EDM are typically within the sensitivities of the next generation experiments. We also analyse the correlation between the electron and neutron EDM, which provides a robust test of Split Supersymmetry.

Electric Dipole Moments in Split Supersymmetry

TL;DR

This work analyzes neutron and electron electric dipole moments in Split Supersymmetry with heavy scalars, where EDMs arise at two loops via the gaugino–Higgsino sector. The authors derive complete analytic expressions for the three two-loop contributions from , , and exchanges, introducing a crucial term that is particularly relevant for the neutron EDM, and they correct the QCD running of quark EDMs. Through a heavy-chargino expansion and a numerical scan in a GUT-inspired parameter space, they show that EDMs can be within next-generation experimental reach and that the electron–neutron EDM correlation provides a stringent test of Split SUSY, albeit with residual hadronic and parameter-space uncertainties. The work clarifies the relative importance of the three diagrams and connects the observable EDMs to CP-violating invariants in the gaugino–Higgsino sector, offering a concrete phenomenological probe of Split SUSY CP violation.

Abstract

We perform a quantitative study of the neutron and electron electric dipole moments (EDM) in Supersymmetry, in the limit of heavy scalars. The leading contributions arise at two loops. We give the complete analytic result, including a new contribution associated with Z-Higgs exchange, which plays an important and often leading role in the neutron EDM. The predictions for the EDM are typically within the sensitivities of the next generation experiments. We also analyse the correlation between the electron and neutron EDM, which provides a robust test of Split Supersymmetry.

Paper Structure

This paper contains 5 sections, 22 equations, 3 figures.

Table of Contents

  1. Introduction
  2. General expressions for the EDMs
  3. Expansions in the heavy-chargino limit
  4. Numerical analysis
  5. Conclusions

Figures (3)

  • Figure 1: Two loop contributions to the light SM fermion EDMs. The third diagram is for a down-type fermion $f$.
  • Figure 2: Prediction for $d_n$, $d_e$, and their ratio $d_n/d_e$. We have chosen $\tan\beta = 1$, $\sin\phi = 1$, and $\tilde{m} = 10^9\,\mathrm{GeV}$. The results for $d_n$ and $d_e$ scale approximately linearly with $\sin 2\beta \sin\phi$, while the ratio is fairly independent of $\tan\beta$, $\sin\phi$ and $\tilde{m}$. The red thick line corresponds to the present experimental limit $d_e< 1.6\times 10^{-27}e\,\mathrm{cm}$Regan:02a.
  • Figure 3: Relative importance of the different contributions to the EDMs. We have chosen $\tan\beta = 1$, $\sin\phi = 1$ and $\tilde{m} = 10^9\,\mathrm{GeV}$, but the result depends only very weakly on this choice.