474 research outputs found
Multiplicity distributions in e+e- annihilation into hadrons and pure birth branching processes
Recursive solution for a general homogeneous in time pure birth branching
process with simultaneous production of any number of particles and with
continuous evolution parameter is given. Calculational algorithm based on the
use of Koenigs function and functional Schroder equation is described. It is
shown that multiplicity distributions in e+e- annihilation into hadrons for
c.m. energies up to 189 GeV are well described by the modified negative
binomial distribution, explained by simple pure birth branching process without
multiple simultaneous particle production. The energy dependence of the
evolution parameter is also discussed.Comment: 10 pages, Latex2e, JHEP.cls, 2 EPS figures, to be published in
Phys.Lett.
Description of local multiplicity fluctuations and genuine multiparticle correlations
Various parametrizations of the multiplicity distribution are studied using
the recently published large statistics OPAL results on multidimensional local
fluctuations and genuine correlations in e+e- -> Z -> hadrons. The measured
normalized factorial and cumulant moments are compared to the predictions of
the negative binomial distribution, the modified and generalized versions of
it, the log-normal distribution and the model of the generalized birth process
with immigration. This is the first study which uses the multiplicity
distribution parametrizations to describe high-order genuine correlations.
Although the parametrizations fit well the measured fluctuations and
correlations for low orders, they do show certain deviations at high orders. We
have shown that it is necessary to incorporate the multiparticle character of
the correlations along with the property of self-similarity to attain a good
description of the measurements.Comment: 15 pages, 2 ps figure
Extraction of Kaon Formfactors from K^- -> mu^- nu_mu gamma Decay at ISTRA+ Setup
The radiative decay K->mu nu gamma has been studied at ISTRA+ setup in a new
kinematical region. About 22K events of K^- -> mu^- nu_mu gamma have been
observed. The sign and value of Fv-Fa have been measured for the first time.
The result is Fv-Fa=0.21(4)(4).Comment: 11 pages, 21 figures, submitted to Phys. Lett.
Modified Negative Binomial Description of the Multiplicity Distributions in Lepton-nucleon Scattering
It is shown that charged hadron multiplicity distributions in lepton-nucleon
scattering are fairly well described by the modified negative binomial
distribution in the energy range from 3-4 to 220 GeV. The energy behaviour of
the parameter k is similar to the dependence observed for e+e- annihilation.Comment: 12 pages, Latex, 2 Poscript figures, epsfig is used, to be published
in Physics Letters
decays revisited: branching ratios and T-odd momenta correlations
We calculate the branching ratios of the decays, and the T-odd triple momenta correlations
, due to the
electromagnetic final state interaction, in these processes. The contributions
on the order of and to the corresponding amplitudes
are treated exactly. For the branching ratios, the corrections on the order of
are estimated and demonstrated to be small. We compare the results
with those of other authors. In some cases our results differ considerably from
the previous ones.Comment: 13 pages, 11 figures; references adde
Search for light pseudoscalar sgoldstino in K- decays
A search for the light pseudoscalar sgoldstino production in the three body
K- decay K-->pipi0P has been performed with the ISTRA+ detector exposed to the
25 GeV negative secondary beam of the U70 proton synchrotron. No signal is
seen. An upper limit for the branching ratio Br(K->pipi0P), at 90% confidence
level, is found to be around 9*10**-6 in the effective mass m(P) range from 0
till 200 MeV, excluding the region near m(pi0) where it degrades to 3.5*10**-5.Comment: 10 pages, LATEX, 8 EPS figures, revised version, to be published in
Phys.Lett.
Measurement of K^+ \to \pi^0 \mu^+ \nu \gamma decay using stopped kaons
The K^+ \to \pi^0 \mu^+ \nu \gamma () decay has been
measured with stopped positive kaons at the KEK 12 GeV proton synchrotron. A
sample containing 125 events was obtained. The partial
branching ratio was found to be , which is in good agreement with theoretical predictions.Comment: 12 pages, 3 figures, to be published in Physics Letters
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