Measurement of the mass and width of the $W$ boson in $e^{+} e^{-}$ collisions at $\sqrt{s}$ = 189-GeV

A measurement of the W mass and width has been performed by the DELPHI Collaboration using the data collected during 1998. The data sample has an integrated luminosity of 155 pb −1 and an average centre-of-mass energy of 188.6 GeV. Results are obtained by applying the method of direct reconstruction of the mass of the W from its decay products in both the W + W − → ℓ ν ̄ ℓ q q ̄ ′ and W + W − → q q ̄ ′ q ̄ q′ channels. The W mass result for the 1998 data set is M W =80.387±0.087(stat)±0.034(syst)±0.017(LEP)±0.035(FSI) GeV/ c 2 , where FSI represents the uncertainty due to final state interaction effects in the q q ̄ ′ q ̄ q′ channel, and LEP represents that arising from the knowledge of the beam energy of the accelerator. Combining this result with those previously published by the DELPHI Collaboration gives the result M W =80.359±0.074(stat)±0.032(syst)±0.017(LEP)±0.033(FSI) GeV/ c 2 . The combined value for the W width is Γ W =2.266±0.176(stat)±0.056(syst)±0.052(FSI) GeV/ c 2 .

Note:

24 pages, 4 figures, Accepted by Phys. Lett. B Report-no: CERN-EP/2001-029

electron positron: colliding beams
electron positron: annihilation
W: pair production
W: leptonic decay
W: hadronic decay
W: mass
W: width
DELPHI
experimental results
CERN LEP Stor

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