Lepton dipole moments in supersymmetric low-scale seesaw models

Amon Ilakovac,Luka Popov,Apostolos Pilaftsis

doi:10.1103/physrevd.89.015001

Abstract

We study the anomalous magnetic and electric dipole moments of charged leptons in supersymmetric low-scale seesaw models with right-handed neutrino superfields. We consider a minimally extended framework of minimal supergravity, by assuming that CP violation originates from complex soft SUSY-breaking bilinear and trilinear couplings associated with the right-handed sneutrino sector. We present numerical estimates of the muon anomalous magnetic moment and the electron electric dipole moment (EDM), as functions of key model parameters, such as the Majorana mass scale mN and tan(\beta). In particular, we find that the contributions of the singlet heavy neutrinos and sneutrinos to the electron EDM are naturally small in this model, of order 10^{-27} - 10^{-28} e cm, and can be probed in the present and future experiments.

Highlights

The anomalous magnetic dipole moment (MDM)of the muon, aμ, constitutes a high-precision observable extremely sensitive to physics beyond the Standard Model (SM)
Our recent analysis has shown [13] that a significant region of the νRMSSM parameter space exists for which the branching ratios of charged lepton flavor violation processes are predicted to be close to the current experimental sensitivities, despite the fact that the soft SUSY-breaking scale has been pushed to values higher than 1 TeV, as a consequence of the discovery of a SM-like Higgs boson at the CERN Large Hadron Collider (LHC) [15] and the existing nonobservation limits on the gluino and squark masses that were deduced from LHC data [16]
One may have new CP-odd phases residing in the 3 × 3 neutrino Yukawa-coupling matrix hν. Assuming that these are the only additional nonzero CP-odd phases in the νRMSSM, we find that the electron electric dipole moment (EDM) is testable, but naturally small, typically of order 10−27e cm, thereby avoiding to some extent the wellknown problem of too large CP violation, from which couplings and the form factors established in [13]

Summary

INTRODUCTION

Of the muon, aμ, constitutes a high-precision observable extremely sensitive to physics beyond the Standard Model (SM). Our recent analysis has shown [13] that a significant region of the νRMSSM parameter space exists for which the branching ratios of charged lepton flavor violation processes are predicted to be close to the current experimental sensitivities, despite the fact that the soft SUSY-breaking scale has been pushed to values higher than 1 TeV, as a consequence of the discovery of a SM-like Higgs boson at the CERN Large Hadron Collider (LHC) [15] and the existing nonobservation limits on the gluino and squark masses that were deduced from LHC data [16]. At the one-loop level, the EDM dl of the lepton vanishes in the MSSM with universal soft SUSY-breaking boundary conditions and no soft CP phases, adopting the convention of a real superpotential Higgs-mixing parameter μ [21] This result holds true, even in extensions of the MSSM with heavy neutrinos, as long as the sneutrino sector is universal and CP-conserving as well. The soft SUSY-breaking terms corresponding to the bν and Aν are obtained from the Lagrangian terms

MAGNETIC AND ELECTRIC DIPOLE MOMENTS

NUMERICAL RESULTS

Results for aμ

Results for de

CONCLUSIONS