1RENARD 1982 derived from $\mathit g-2$ data limits on mass and couplings of ${{\mathit e}^{*}}$ and ${{\mathit \mu}^{*}}$. See figures 2 and 3 of the paper.
References:
RENARD
1982
PL 116B 264
Limits on Masses and Couplings of Excited Electrons and Muons