English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We reconsider the issue of the search for a nonzero electric dipole formfactor (EDM) $d_\tau(s)$ using optimal observables in $\tau^+\tau^-$ productionby $e^+ e^-$ collisions in the center-of-mass energy range from the $\tau$-pairthreshold to about $\sqrt{s} \sim 15$ GeV. We discuss the general formalism ofoptimal observables and apply it to two $CP$-odd observables that are sensitiveto the real and imaginary part of $d_\tau(s)$, respectively. We compute theexpectation 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 totwo pions and three charged pions we take the full kinematic information of thehadronic system into account. Assuming that the Belle II experiment at the KEKBaccelerator will eventually  analyze data corresponding to an integrated luminosity of 50 ab$^{-1}$ andapplying acceptance cuts on the final-state pions we find that 1~s.d.sensitivities $\delta {\rm Re} d_\tau = 6.8 \times 10^{-20}$ e cm and $\delta{\rm} Im d_\tau = 4.0 \times 10^{-20}$ e cm can be obtained with events whereboth $\tau$'s decay semihadronically.  In the ideal case where no cuts on the final-state particles are applied wefind with 50 ab$^{-1}$ at $\sqrt{s}=10.58$ GeV corresponding to $4.5 \times10^{10}$ $\tau^+ \tau^-$ events the 1 s.d. sensitivities $\delta {\rm Re}d_\tau = 5.8 \times 10^{-20}$ e cm and $\delta {\rm} Im d_\tau = 3.2 \times10^{-20}$ e cm, again for events where both $\tau$ leptons decaysemihadronically. Furthermore, we analyze the potential magnitude of the $\tau$EDM form factor in the type-II two-Higgs doublet extension and in two scalarleptoquark extensions of the Standard Model.

The electric dipole moment of the tau lepton revisited