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Search for anomalous weak dipole moments of the \(\tau\) lepton

  • The ALEPH Collaboration
experimental physics

Abstract.

The anomalous weak dipole moments of the \(\tau\) lepton are measured in a data sample collected by ALEPH from 1990 to 1995 corresponding to an integrated luminosity of 155 pb-1. Tau leptons produced in the reaction \(e^+ e^- \rightarrow \tau^+ \tau^-\) at energies close to the \({\rm Z}\) mass are studied using their semileptonic decays to \(\pi\), \(\rho\), \(a_1 \rightarrow \pi 2\pi^0\) or \(a_1 \rightarrow 3 \pi\). The real and imaginary components of both the anomalous weak magnetic dipole moment and the CP-violating anomalous weak electric dipole moment, \( {\rm Re} \mu_{\tau}\), \({\rm Im} \mu_{\tau}\), \({\rm Re} d_{\tau}\) and \({\rm Im} d_{\tau}\), are measured simultaneously by means of a likelihood fit built from the full differential cross section. No evidence of new physics is found. The following bounds are obtained (95% CL): \(\vert{\rm Re} \mu_{\tau} \vert < 1.14 \times 10^{-3}\), \(\vert{\rm Im} \mu_{\tau} \vert < 2.65 \times 10^{-3}\), \(\vert{\rm Re} d_{\tau} \vert < 0.91 \times 10^{-3}\), and \(\vert{\rm Im} d_{\tau} \vert < 2.01 \times 10^{-3}\).

Keywords

Dipole Moment Electric Dipole Magnetic Dipole Differential Cross Section Differential Cross 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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© Springer-Verlag Berlin/Heidelberg 2003

Authors and Affiliations

  • The ALEPH Collaboration

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