Dipole moments of tau as a sensitive probe for beyond standard model physics

Abstract

CP violating dipole moments of leptons vanish at least to three loop order and are estimated to be $(\frac{m_l}{Mev})\times 1.6\times 10^{-40}$ e-cm in the standard model (SM), where $m_l$ is the mass of the lepton. However they can receive potentially large contributions in some beyond SM scenarios and this makes them very sensitive probes of new physics. In this article we show that a non universal interaction, involving leptoquarks to the quark-lepton pair of the third generation through helicity unsuppressed couplings of the order of ordinary gauge couplings, can generate electric and weak dipole moments of the order of $10^{-19}$ e-cm for the tau lepton. This is greater than pure supersymmetric (SUSY) and left-right (L-R) contributions by almost three orders of magnitude. It is also greater than mirror fermionic contribution by an order of magnitude. The measurements of $\dzt$ and $\dgt$ at LEP, SLC and TCF are expected to reach sensitivities of $10^{-18}$ e-cm and $10^{-19}$ e-cm respectively in near future. The observation of a non vanishing dipole moment of tau at these facilities would therefore strongly favour superstring inspired light leptoquark mediated interactions, over pure SUSY or L-R interactions and perhaps also mirror generated mixings without some sort of quark-lepton unification as its origin.

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References in corpus (3)

• Bounds on Scalar Leptoquarks from Z Physics
• Weak dipole moment of $\tau$ in $e^{+}{e}^{-}$ collisions with longitudinally polarized electrons
• Measurement of the $\tau$ electric dipole moment using longitudinal polarization of $e^{+}{e}^{-}$ beams

Cited by in corpus (8)

• Fermion Dipole Moments in Supersymmetric Models with Explicitly Broken R-parity
• An improved search for the electric dipole moment of the $\tau$ lepton
• One-loop RGEs for two left-right SUSY models
• Search For Non-Standard Model CP/T violation At Tau-Charm Factory
• Vector leptoquark contributions to lepton dipole moments
• Revisiting the Scalar Leptoquark ($S_1$) Model with the Updated Leptonic Constraints
• Manifestation of the electric dipole moment in the decays of $\tau$ leptons produced in $e^{+}{e}^{-}$ annihilation
• Sensitivity Study of the Tau Lepton Electric Dipole Moment at the Super Tau-Charm Facility