1,140 research outputs found
Symmetric Gibbs measures
We prove that certain Gibbs measures on subshifts of finite type are
nonsingular and ergodic for certain countable equivalence relations, including
the orbit relation of the adic transformation (the same as equality after a
permutation of finitely many coordinates). The relations we consider are
defined by cocycles taking values in groups, including some nonabelian ones.
This generalizes (half of) the identification of the invariant ergodic
probability measures for the Pascal adic transformation as exactly the
Bernoulli measures---a version of de Finetti's Theorem. Generalizing the other
half, we characterize the measures on subshifts of finite type that are
invariant under both the adic and the shift as the Gibbs measures whose
potential functions depend on only a single coordinate. There are connections
with and implications for exchangeability, ratio limit theorems for transient
Markov chains, interval splitting procedures, `canonical' Gibbs states, and the
triviality of remote sigma-fields finer than the usual tail field
Small dense LDL particles - a predictor of coronary artery disease evaluated by invasive and CT-based techniques: a case-control study
Search for Heavy Isosinglet Neutrino in e+e- Annihilation at LEP
We report on a search for the first generation heavy neutrino that is an
isosinglet under the standard SU(2)_L gauge group. The data collected with the
L3 detector at center-of-mass energies between 130 GeV and 208 GeV are used.The
decay channel N_e --> eW is investigated and no evidence is found for a heavy
neutrino, N_e, in a mass range between 80 GeV and 205 GeV. Upper limits on the
mixing parameter between the heavy and light neutrino are derived
Formation of the in Two-Photon Collisions at LEP
The two-photon width of the meson has been
measured with the L3 detector at LEP. The is studied in the decay
modes , KK, KK,
KK, , , and
using an integrated luminosity of 140 pb at GeV and
of 52 pb at GeV. The result is
(BR) keV. The dependence of the cross section is studied for
GeV. It is found to be better described by a Vector Meson
Dominance model form factor with a J-pole than with a -pole. In addition,
a signal of events is observed at the mass. Upper limits
for the two-photon widths of the , , and are also
given
Direct Observation of Longitudinally Polarised W Bosons
The three different helicity states of W bosons, produced in the reaction
e+e- -> W+W- -> l nu q q~ are studied using leptonic and hadronic W decays at
sqrt{s}=183GeV and 189GeV. The W polarisation is also measured as a function of
the scattering angle between the W- and the direction of the e- beam. The
analysis demonstrates that W bosons are produced with all three helicities, the
longitudinal and the two transverse states. Combining the results from the two
center-of-mass energies and with leptonic and hadronic W decays, the fraction
of longitudinally polarised W bosons is measured to be 0.261 +/- 0.051(stat.)
+/- 0.016(syst.) in agreement with the expectation from the Standard Model
Study of Z Boson Pair Production in e^+e^- Interactions at \sqrt{s}=192 - 202 GeV
The cross section for the production of Z boson pairs is measured using the
data collected by the L3 detector at LEP in 1999 in e^+e^- collisions at
centre-of-mass energies ranging from 192 GeV up to 202 GeV. Events in all the
visible final states are selected, measuring the cross section of this process.
The special case of final states containing b quarks is also investigated. All
results are in agreement with the Standard Model predictions
Study of Z Boson Pair Production in e+e- Collisions at LEP at \sqrt{s}=189 GeV
The pair production of Z bosons is studied using the data collected by the L3
detector at LEP in 1998 in e+e- collisions at a centre-of-mass energy of 189
GeV. All the visible final states are considered and the cross section of this
process is measured to be 0.74 +0.15 -0.14 (stat.) +/- 0.04 (syst.) pb. Final
states containing b quarks are enhanced by a dedicated selection and their
production cross section is found to be 0.18 +0.09 -0.07 (stat.) +/- 0.02
(syst.) pb. Both results are in agreement with the Standard Model predictions.
Limits on anomalous couplings between neutral gauge bosons are derived from
these measurements
Search for Scalar Leptons in e+e- collisions at \sqrt{s}=189 GeV
We report the result of a search for scalar leptons in e+e- collisions at 189
GeV centre-of-mass energy at LEP. No evidence for such particles is found in a
data sample of 176 pb^{-1}. Improved upper limits are set on the production
cross sections for these new particles. New exclusion contours in the parameter
space of the Minimal Supersymmetric Standard Model are derived, as well as new
lower limits on the masses of these supersymmetric particles. Under the
assumptions of common gaugino and scalar masses at the GUT scale, we set an
absolute lower limit on the mass of the lightest scalar electron of 65.5 Ge
- …