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Number from ${{\boldsymbol e}^{+}}{{\boldsymbol e}^{-}}$ Colliders

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.

VALUE

DOCUMENT ID

TECN

COMMENT

$\bf{ 2.92 \pm0.05}$

OUR AVERAGE Error includes scale factor of 1.2.

$2.84$ $\pm0.10$ $\pm0.14$

DLPH

$\sqrt {s }$ = $180 - 209$ GeV

$2.98$ $\pm0.05$ $\pm0.04$

L3

1990-2000 LEP runs

$2.86$ $\pm0.09$

ALEP

$\sqrt {s }$ = $189 - 209$ GeV

$2.69$ $\pm0.13$ $\pm0.11$

OPAL

1998 LEP run

$2.89$ $\pm0.32$ $\pm0.19$

DLPH

1993--1994 LEP runs

$3.23$ $\pm0.16$ $\pm0.10$

OPAL

$1990 - 1992$ LEP runs

$2.68$ $\pm0.20$ $\pm0.20$

ALEP

$1990 - 1991$ LEP runs

• • • We do not use the following data for averages, fits, limits, etc. • • •

$2.84$ $\pm0.15$ $\pm0.14$

DLPH

$1997 - 1998$ LEP runs

$3.01$ $\pm0.08$

L3

$1991 - 1998$ LEP runs

$3.1$ $\pm0.6$ $\pm0.1$

DLPH

$\sqrt {\mathit s }$ = 130, 136 GeV

References:

EPJ C38 395

Photon Events with Missing Energy in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Collisions at $\sqrt {s }$ = 130 to 209 GeV

PL B587 16

Single Photon and Multiphoton Events with Missing Energy in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Collisions at LEP

EPJ C28 1

Single Photon and Multiphoton Production in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Collisions at $\sqrt {s }$ up to 209 GeV

EPJ C18 253

Photonic Events with Missing Energy in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Collisions at $\sqrt {s }$ = 189 GeV

EPJ C17 53

Photon Events with Missing Energy at $\sqrt {s }$ = 183 to 189-GeV

PL B470 268

Single and Multiphoton Events with Missing Energy in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Collisions at $\sqrt {s }$ = 189 GeV

ZPHY C74 577

Search for New Phenomena using Single Photon Events in the DELPHI Detector at LEP

PL B380 471

Search for Anomalous Production of Single Photons at $\sqrt {s }$ = 130 and 136 GeV

ZPHY C65 47

Measurement of Single Photon Production in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Collisions near the ${{\mathit Z}^{0}}$ Resonance

PL B313 520

A Direct Measurement of the Invisible Width of the ${{\mathit Z}}$ from Single Photon Counting