These limits are from ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \nu}}{{\mathit \nu}^{*}}$ , ${{\mathit Z}}$ $\rightarrow$ ${{\mathit \nu}}{{\mathit \nu}^{*}}$ , or ${{\mathit e}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \nu}^{*}}{{\mathit X}}$ and depend on transition magnetic coupling between ${{\mathit \nu}}/{{\mathit e}}$ and ${{\mathit \nu}^{*}}$. Assumptions about ${{\mathit \nu}^{*}}$ decay mode are given in footnotes.

VALUE (GeV) CL% DOCUMENT ID TECN  COMMENT $\bf{> 213}$ 95 1 AARON 2008 H1 ${{\mathit e}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \nu}^{*}}{{\mathit X}}$ • • We do not use the following data for averages, fits, limits, etc. • • $>190$ 95 2 ACHARD 2003 B L3 ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \nu}}{{\mathit \nu}^{*}}$ $\text{none 50 - 150}$ 95 3 ADLOFF 2002 H1 ${{\mathit e}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \nu}^{*}}$ X $>158$ 95 4 CHEKANOV 2002 D ZEUS ${{\mathit e}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \nu}^{*}}$ X 1  AARON 2008 search for single ${{\mathit \nu}^{*}}$ production in ${{\mathit e}}{{\mathit p}}$ collisions with the decays ${{\mathit \nu}^{*}}$ $\rightarrow$ ${{\mathit \nu}}{{\mathit \gamma}}$ , ${{\mathit \nu}}{{\mathit Z}}$ , ${{\mathit e}}{{\mathit W}}$ . The quoted limit assumes $\mathit f$ = $−{{\mathit f}^{\,'}}$ = $\Lambda /{\mathit m}_{{{\mathit \nu}^{*}}}$. See their Fig. 3 and Fig. 4 for the exclusion plots in the mass-coupling plane. 2  ACHARD 2003B result is from ${{\mathit e}^{+}}{{\mathit e}^{-}}$ collisions at $\sqrt {\mathit s }$ = $189 - 209$ GeV. The quoted limit is for ${{\mathit \nu}_{{e}}^{*}}$. ${{\mathit f}}$ = $\text{-}{{\mathit f}^{\,'}}$ = $\Lambda /{\mathit m}_{{{\mathit \nu}^{*}}}$ is assumed. See their Fig.$~$4 for the exclusion plot in the mass-coupling plane. 3  ADLOFF 2002 search for single ${{\mathit \nu}^{*}}$ production in ${{\mathit e}}{{\mathit p}}$ collisions with the decays ${{\mathit \nu}^{*}}$ $\rightarrow$ ${{\mathit \nu}}{{\mathit \gamma}}$ , ${{\mathit \nu}}{{\mathit Z}}$ , ${{\mathit e}}{{\mathit W}}$ . The quoted limit assumes ${{\mathit f}}$ = $−{{\mathit f}^{\,'}}$ = $\Lambda /{\mathit m}_{{{\mathit \nu}^{*}}}$. See their Fig.$~$1 for the exclusion plots in the mass-coupling plane. 4  CHEKANOV 2002D search for single ${{\mathit \nu}^{*}}$ production in ${{\mathit e}}{{\mathit p}}$ collisions with the decays ${{\mathit \nu}^{*}}$ $\rightarrow$ ${{\mathit \nu}}{{\mathit \gamma}}$ , ${{\mathit \nu}}{{\mathit Z}}$ , ${{\mathit e}}{{\mathit W}}$ . ${{\mathit f}}$ = $−{{\mathit f}^{\,'}}$ = $\Lambda /{\mathit m}_{{{\mathit \nu}^{*}}}$ is assumed for the ${{\mathit e}^{*}}$ coupling. CHEKANOV 2002D also obtain limit for ${{\mathit f}}$ = ${{\mathit f}^{\,'}}$ = $\Lambda /{\mathit m}_{{{\mathit \nu}^{*}}}$: ${\mathit m}_{{{\mathit \nu}^{*}}}>$135 GeV. See their Fig.$~$5c and Fig.$~$5d for the exclusion plot in the mass-coupling plane.

References:

AARON 2008 PL B663 382 A Search for Excited Neutrinos in ${{\mathit e}^{-}}{{\mathit p}}$ Collisions at HERA ACHARD 2003B PL B568 23 Search for Excited Leptons at LEP ADLOFF 2002 PL B525 9 Search for Excited Neutrinos at HERA CHEKANOV 2002D PL B549 32 Searches for Excited Fermions in ${{\mathit e}}{{\mathit p}}$ Collisions at HERA