The electric dipole moment of the tau lepton revisited

Abstract

We reconsider the issue of the search for a nonzero electric dipole form factor (EDM) $d_{\tau }(s)$ using optimal observables in ${\tau }^{+}{\tau }^{-}$ production by $e^{+}{e}^{-}$ collisions in the center-of-mass energy range from the $\tau$-pair threshold to about $\sqrt{s}\sim 15$ GeV. We discuss the general formalism of optimal observables and apply it to two $CP$-odd observables that are sensitive to the real and imaginary part of $d_{\tau }(s)$, respectively. We compute the expectation values and covariances of these optimal $CP$ observables for $\tau$-pair production at $\sqrt{s}=10.58$ GeV with subsequent decays of ${\tau }^{\pm }$ into major leptonic or semihadronic modes. For the $\tau$ decays to two pions and three charged pions we take the full kinematic information of the hadronic system into account. Assuming that the Belle II experiment at the KEKB accelerator will eventually analyze data corresponding to an integrated luminosity of 50 ab${}^{-1}$ and applying acceptance cuts on the final-state pions we find that 1~s.d. sensitivities $\delta \mathrm{Re}{d}_{\tau }=6.8\times 10^{-20}$ e cm and $\delta Im{d}_{\tau }=4.0\times 10^{-20}$ e cm can be obtained with events where both $\tau$'s decay semihadronically. In the ideal case where no cuts on the final-state particles are applied we find with 50 ab${}^{-1}$ at $\sqrt{s}=10.58$ GeV corresponding to $4.5\times 10^{10}$ ${\tau }^{+}{\tau }^{-}$ events the 1 s.d. sensitivities $\delta \mathrm{Re}{d}_{\tau }=5.8\times 10^{-20}$ e cm and $\delta Im{d}_{\tau }=3.2\times 10^{-20}$ e cm, again for events where both $\tau$ leptons decay semihadronically. Furthermore, we analyze the potential magnitude of the $\tau$ EDM form factor in the type-II two-Higgs doublet extension and in two scalar leptoquark extensions of the Standard Model.

Two tables, one figure, and references added. Version to be published in Phys. Rev. D

References in corpus (9)

• Search for heavy Higgs bosons decaying into two tau leptons with the ATLAS detector using $pp$ collisions at $\sqrt{s}=13$ TeV
• $(g-2{)}_{\mu }$, Lepton Flavour Violation and $Z$ Decays with Leptoquarks: Correlations and Future Prospects
• Large long-distance contributions to the electric dipole moments of charged leptons in the standard model
• Getting chirality right: single scalar leptoquark solutions to the $(g-2{)}_{e,\mu }$ puzzle
• Tau and muon pair production cross-sections in electron-positron annihilations at sqrt{s} = 10.58 GeV
• Anomalous electromagnetic moments of $\tau$ lepton in $\gamma \gamma \to {\tau }^{+}{\tau }^{-}$ reaction in Pb+Pb collisions at the LHC
• Tau anomalous magnetic moment form factor at Super B/Flavor factories
• Scalar Leptoquarks in Leptonic Processes
• CP violation and electric-dipole-moment at low energy $\tau$ production with polarized electrons

Cited by in corpus (14)

• Reflecting on chirality: CP-violating extensions of the single scalar-leptoquark solutions for the $(g-2{)}_{e,\mu }$ puzzles and their implications for lepton EDMs
• Constraining Lepton Flavor Violating Higgs Couplings at the HL-LHC in the Vector Boson Fusion Channel
• Charged Lepton EDM with Extra Yukawa Couplings
• New Physics Search at the CEPC: a General Perspective
• Flavor Physics at the CEPC: a General Perspective
• Reevaluation of heavy-fermion-induced electron EDM at three loops
• Interference Resurrection of the $\tau$ Dipole through Quantum Tomography
• Spin correlations in $\tau$-lepton pair production due to anomalous magnetic and electric dipole moments
• Probing the tau electric dipole moment at BEPC-II collider energies
• Flavour anomalies meet flavour symmetry
• Sensitivity Study of the Tau Lepton Electric Dipole Moment at the Super Tau-Charm Facility
• Hadronic Currents and Form Factors in three-body Semileptonic $\tau$ Decays
• Linearly Polarized Photon Fusion as a Precision Probe of the Tau Lepton Dipole Moments at Lepton Colliders
• Electric and Magnetic Tau Dipole Moments Revisited