Are light sneutrinos buried in LEP data?

Abstract

Supersymmetry may resolve the disagreement between the precision electroweak data and the direct limit on the higgs mass, if there are light sneutrinos in the mass range 55 GeV $ < m_{\snu} < $ 80 GeV. Such sneutrinos should decay invisibly with 100% branching ratio and contribute to the $γ$ + missing energy signal, investigated by all the LEP groups. It is shown that while the data accumulated by a single group may not be adequate to reveal such sneutrinos, a combined analysis of the data collected by all four groups will be sensitive to $m_{\snu}$ in the above range. If no signal is found a lower bound on $m_{\snu}$ stronger than that obtained from the $Z$-pole data may emerge.