14 research outputs found
Measurement of Mass and Width of the W Boson at LEP
We report on measurements of the mass and total decay width of the W boson
with the L3 detector at LEP. W-pair events produced in
interactions between 161 GeV and 183 GeV centre-of-mass energy are selected in
a data sample corresponding to a total luminosity of 76.7 pb. Combining
all final states in W-pair production, the mass and total decay width of the W
boson are determined to be GeV and
GeV, respectively
Search for Heavy Neutral and Charged Leptons in ee Annihilation at = 183 and 189 GeV
A search for unstable neutral and charged heavy leptons as well as for stable
charged heavy leptons is performed at center-of-mass energies = 183
and 189 GeV with the L3 detector at LEP. No evidence for their existence is
found. We exclude neutral heavy leptons which couple to the electron, muon or
tau family, of the Dirac type for masses below 92.4, 93.3 and 83.3 GeV, and of
the Majorana type for masses below 81.8, 84.1 and 73.5 GeV, respectively. We
exclude unstable charged heavy leptons for masses below 93.9 GeV for a wide
range of the associated neutral heavy lepton mass. If the unstable charged
heavy lepton decays to a light neutrino, we exclude masses below 92.4 GeV. The
production of stable charged heavy leptons with mass less than 93.5 GeV is also
excluded
Measurement of an Elongation of the Pion Source in Z Decays
We measure Bose-Einstein correlations between like-sign charged pion pairs in
hadronic Z decays with the L3 detector at LEP. The analysis is performed in
three dimensions in the longitudinal center-of-mass system. The pion source is
found to be elongated along the thrust axis with a ratio of transverse to
longitudinal radius of
Search for R-parity Violating Decays of Supersymmetric Particles in Collisions at LEP
A search, in collisions, for chargino, neutralino, scalar lepton and scalar quark pair-production is performed, without assuming R-parity conservation in decays, in the case that only one of the coupling constants or is non-negligible. No signal is found in data up to a centre-of-mass energy of 208 \GeV. Limits on the production cross sections and on the masses of supersymmetric particles are derived.A search, in e + e − collisions, for chargino, neutralino, scalar lepton and scalar quark pair-production is performed, without assuming R-parity conservation in decays, in the case that only one of the coupling constants λ or λ ″ is non-negligible. No signal is found in data up to a centre-of-mass energy of 208 GeV. Limits on the production cross sections and on the masses of supersymmetric particles are derived.A search, in e^+e^- collisions, for chargino, neutralino, scalar lepton and scalar quark pair-production is performed, without assuming R-parity conservation in decays, in the case that only one of the coupling constants lambda_ijk or lambda''_ijk is non-negligible. No signal is found in data up to a centre-of-mass energy of 208GeV. Limits on the production cross sections and on the masses of supersymmetric particles are derived
Search for Heavy Isosinglet Neutrinos in ee Annihilation at 130189 GeV
A search for heavy neutrinos that are isosinglets under the standard
gauge group is made at center-of-mass energies 130 189
GeV with the L3 detector at LEP. Such heavy neutrinos are expected in many
extensions of the Standard Model. The search is performed for the first
generation heavy singlet neutrino, , through the decay mode
. We set upper limits on the mixing
parameter between the heavy and light neutrino for the heavy neutrino mass
range from 80 GeV to 185 GeV
Study of hadronic event shape in flavour tagged events in e+e- annihilation at = 197 GeV
Results are presented from a study of the structure of hadronic events in
high-energy e+e- interactions detected by the L3 detector at LEP. Various event
shape distributions and their moments are measured at several energy points at
and above the Z-boson mass. The event flavour is tagged by using the decay
characteristics of b-hadrons. Measurements of distributions of event shape
variables for all hadronic events, for light (u, d, s, c) and heavy (b) quark
flavours are compared to several QCD models with improved leading log
approximation: JETSET, HERWIG and ARIADNE. A good description of the data is
provided by the models.Comment: 29 pages, 9 figure
Measurement of exclusive production in two-photon collisions at high at LEP
Exclusive rho rho production in two-photon collisions involving a single highly virtual photon is studied with data collected at LEP at centre-of-mass energies 89GeV rho rho is determined as a function of the photon virtuality, Q^2 and the two-photon centre-of-mass energy, Wgg, in the kinematic region: 1.2GeV^2 < Q^2 < 30GeV^2 and 1.1GeV < Wgg < 3GeV
Analysis of the and final states in quasi-real two-photon collisions at LEP.
The reactions gamma gamma -> pi^+pi^-pi^+pi^- and gamma gamma ->
pi^+pi^0pi^-pi^0 are studied with the L3 detector at LEP in a data sample
collected at centre-of-mass energies from 161GeV to 209GeV with a total
integrated luminosity of 698/pb. A spin-parity-helicity analysis of the rho^0
rho^0 and rho^+ rho^- systems for two-photon centre-of-mass energies between
1GeV and 3GeV shows the dominance of the spin-parity state 2+ with helicity 2.
The contribution of 0+ and 0- spin-parity states is also observed, whereas
contributions of 2- states and of a state with spin-parity 2+ and zero helicity
are found to be negligible
Measurement of hadron and lepton-pair production in e+e- collisions at .
Contains fulltext :
35697.pdf ( ) (Open Access