Fermion Dipole Moments in Supersymmetric Models with Explicitly Broken R-parity

TL;DR

This paper analyzes fermion dipole moments in supersymmetric models with broken R-parity, showing that R-parity violating contributions to electric dipole moments occur at two loops and are less constrained than previously thought.

Contribution

It provides explicit calculations of dipole moments in R-parity violating supersymmetry and corrects prior claims about the loop level and bounds on couplings.

Findings

R-parity violating contributions to EDMs occur at two loops

Enhancement of lepton dipole moments is by m_b/m_l, not m_t/m_l

Experimental bounds are less restrictive than previously claimed

Abstract

We present a simple analysis that allows us to extract the leading mass dependence of the dipole moment of matter fermions that might be induced by new physics. We present explicit results for the supersymmetric model with broken R-parity as an illustration. We show that the extra contributions to the electric dipole moment (edm) of fermions from R-parity violating interactions can occur only at two loop level, contrary to claims in the literature. We further find that unlike the generic lepto-quark models, the extra contributions to the dipole moments of the leptons can only be enhanced by m_b/m_l and not by m_t/m_l relative to the expectations in the Standard Model. An interesting feature about this enhancement of these dipole moments is that it does not involve unknown mixing angles. We then use experimental constraints on the electric dipole moments of electron and neutron to obtain bounds on (the imaginary part of) products of R-parity violating couplings, and show that bounds claimed in the literature are too stringent by many orders of magnitude.