An Improved search for the electric dipole moment of the lepton

Inami, Kenji*; Tanida, Kiyoshi   ; Belle Collaboration*; 186 of others*

We report a measurement of the electric dipole moment of the lepton () using an 833~fb data sample collected near the resonance, with the Belle detector at the KEKB asymmetric-energy collider. Using an optimal observable method, we obtain the real and imaginary parts of as and , respectively. These results are consistent with null electric dipole moment at the present level of experimental sensitivity and improve the sensitivity by about a factor of three.