An upper limit for the $\mathrm\tau$–neutrino mass from $\tau\rightarrow 5\pi^{\pm}\nu_{\tau}$ decays

The OPAL Collaboration:     K. Ackerstaff - et al.

doi:doi:10.1007/s100520050264

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2023 Impact factor 4.2

Particles and Fields

Eur. Phys. J. C 5, 229-237
DOI 10.1007/s100529800976

An upper limit for the $\mathrm\tau$ -neutrino mass from $\tau\rightarrow 5\pi^{\pm}\nu_{\tau}$ decays

The OPAL Collaboration
K.Ackerstaff $^{\rm 8}$ - et al.

$^{\rm 8}$ CERN, European Organisation for Particle Physics, CH-1211 Geneva 23, Switzerland

Received: 15 April 1998 / Published online: 12 August 1998

Abstract
An upper limit for the $\tau$ -neutrino mass has been determined from the decay $\tau\rightarrow 5\pi^{\pm}\nu_{\tau}$ using data collected with the OPAL detector from 1991 to 1995 in $\rm e^{+}e^{-}$ collisions at $\sqrt{s}\approx M_\mathrm{Z}$ . A limit of 43.2MeV at 95% CL is obtained using a two-dimensional method in the $5\pi$ invariant mass and energy distribution from 22 selected events. Combining this result with OPAL's previously published measurement using $\rm \tau^{+}\tau^{-}\rightarrow 3h^{\pm}\bar{\nu}_{\tau}+3h^{\mp}\nu_{\tau}$ decays, a new combined limit of $m_{\nu_{\tau}}<27.6$ MeV (95% CL) is obtained.