1BARGER 1989 used ABE 1989B limit for events with large missing transverse momentum. Two-body decay ${{\mathit \nu}_{{8}}}$ $\rightarrow$ ${{\mathit \nu}}{{\mathit g}}$ is assumed.
2KIM 1990 is at $\mathit E_{{\mathrm {cm}}}$ = $50-60.8$ GeV. The same assumptions as in BARTEL 1987B are used.
3BARTEL 1987B is at $\mathit E_{{\mathrm {cm}}}$ = $46.3-46.78$ GeV. The limit assumes the ${{\mathit \nu}_{{8}}}$ pair production cross section to be eight times larger than that of the corresponding heavy neutrino pair production. This assumption is not valid in general for the weak couplings, and the limit can be sensitive to its SU(2)$_{\mathit L}{\times }U(1)_{\mathit Y}$ quantum numbers.
References:
KIM
1990
PL B240 243
A Search for Leptoquark and Colored Lepton Pair Production in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilations at TRISTAN
BARGER
1989
PL B220 464
Constraints on Exotic Particles from Tevatron Missing Transverse Momentum Data
BARTEL
1987B
ZPHY C36 15
Search for Leptoquarks and other New Particles with Lepton Hadron Signature in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Interactions