Number of Light ${{\boldsymbol \nu}}$ Types from Direct Measurement of Invisible ${{\boldsymbol Z}}$ Width
INSPIRE search
In the following, the invisible ${{\mathit Z}}$ width is obtained from studies of single-photon events from the reaction ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \nu}}{{\overline{\mathit \nu}}}{{\mathit \gamma}}$ . All are obtained from LEP runs in the ${\it{}E}^{\it{}ee}_{\rm{}cm}$ range $88 - 209$ GeV.