An improved search for the electric dipole moment of the ? lepton

Abstract

We report a measurement of the electric dipole moment of the ? lepton (d?) using an 833 fb?1 data sample collected near the ?(4S) resonance, with the Belle detector at the KEKB asymmetric-energy e+e? collider. Using an optimal observable method, we obtain the real and imaginary parts of d? as Re(d?) = (?0.62 � 0.63) � 10?17ecm and Im(d?) = (?0.40 � 0.32) � 10?17ecm, 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. [Figure not available: see fulltext.] � 2022, The Author(s).