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.
$2.84$ $\pm0.10$ $\pm0.14$
ABDALLAH
2005B
DLPH $\sqrt {s }$ = $180 - 209$ GeV
$2.98$ $\pm0.05$ $\pm0.04$
ACHARD
2004E
L3 1990-2000 LEP runs
$2.86$ $\pm0.09$
HEISTER
2003C
ALEP $\sqrt {s }$ = $189 - 209$ GeV
$2.69$ $\pm0.13$ $\pm0.11$
ABBIENDI,G
2000D
OPAL 1998 LEP run
$2.89$ $\pm0.32$ $\pm0.19$
ABREU
1997J
DLPH 1993--1994 LEP runs
$3.23$ $\pm0.16$ $\pm0.10$
AKERS
1995C
OPAL $1990 - 1992$ LEP runs
$2.68$ $\pm0.20$ $\pm0.20$
BUSKULIC
1993L
ALEP $1990 - 1991$ LEP runs
• • • We do not use the following data for averages, fits, limits, etc. • • •
$2.84$ $\pm0.15$ $\pm0.14$
ABREU
2000Z
DLPH $1997 - 1998$ LEP runs
$3.01$ $\pm0.08$
ACCIARRI
1999R
L3 $1991 - 1998$ LEP runs
$3.1$ $\pm0.6$ $\pm0.1$
ADAM
1996C
DLPH $\sqrt {\mathit s }$ = 130, 136 GeV
  References:
ABDALLAH 2005B
EPJ C38 395 Photon Events with Missing Energy in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Collisions at $\sqrt {s }$ = 130 to 209 GeV
ACHARD 2004E
PL B587 16 Single Photon and Multiphoton Events with Missing Energy in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Collisions at LEP
HEISTER 2003C
EPJ C28 1 Single Photon and Multiphoton Production in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Collisions at $\sqrt {s }$ up to 209 GeV
ABBIENDI,G 2000D
EPJ C18 253 Photonic Events with Missing Energy in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Collisions at $\sqrt {s }$ = 189 GeV
ABREU 2000Z
EPJ C17 53 Photon Events with Missing Energy at $\sqrt {s }$ = 183 to 189-GeV
ACCIARRI 1999R
PL B470 268 Single and Multiphoton Events with Missing Energy in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Collisions at $\sqrt {s }$ = 189 GeV
ABREU 1997J
ZPHY C74 577 Search for New Phenomena using Single Photon Events in the DELPHI Detector at LEP
ADAM 1996C
PL B380 471 Search for Anomalous Production of Single Photons at $\sqrt {s }$ = 130 and 136 GeV
AKERS 1995C
ZPHY C65 47 Measurement of Single Photon Production in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Collisions near the ${{\mathit Z}^{0}}$ Resonance
BUSKULIC 1993L
PL B313 520 A Direct Measurement of the Invisible Width of the ${{\mathit Z}}$ from Single Photon Counting