These limits are obtained from ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \tau}^{*+}}{{\mathit \tau}^{*-}}$ and thus rely only on the (electroweak) charge of ${{\mathit \tau}^{*}}$. Form factor effects are ignored unless noted. For the case of limits from ${{\mathit Z}}$ decay, the ${{\mathit \tau}^{*}}$ coupling is assumed to be of sequential type. All limits assume a dominant ${{\mathit \tau}^{*}}$ $\rightarrow$ ${{\mathit \tau}}{{\mathit \gamma}}$ decay except the limits from $\Gamma\mathrm {({{\mathit Z}})}$.

For limits prior to 1987, see our 1992 edition (Physical Review D45 S1 (1992)).

VALUE (GeV) CL% DOCUMENT ID TECN  COMMENT $\bf{>103.2}$ 95 1 ABBIENDI 2002 G OPAL ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \tau}^{*}}{{\mathit \tau}^{*}}$ Homodoublet type • • We do not use the following data for averages, fits, limits, etc. • • $>102.8$ 95 2 ACHARD 2003 B L3 ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \tau}^{*}}{{\mathit \tau}^{*}}$ Homodoublet type 1  From ${{\mathit e}^{+}}{{\mathit e}^{-}}$ collisions at $\sqrt {\mathit s }$ = $183 - 209$ GeV. ${{\mathit f}}$ = ${{\mathit f}^{\,'}}$ is assumed. 2  From ${{\mathit e}^{+}}{{\mathit e}^{-}}$ collisions at $\sqrt {\mathit s }$ = $189 - 209$ GeV. ${{\mathit f}}$ = ${{\mathit f}^{\,'}}$ is assumed. ACHARD 2003B also obtain limit for ${{\mathit f}}$ = $−{{\mathit f}^{\,'}}$: ${\mathit m}_{{{\mathit \tau}^{*}}}>96.6$ GeV.

References:

ACHARD 2003B PL B568 23 Search for Excited Leptons at LEP ABBIENDI 2002G PL B544 57 Search for Charged Excited Leptons in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Collisions at $\sqrt {s }$ = 183-GeV to 209-GeV