166 research outputs found
On Asymptotic Expansion in the Random Allocation of Particles by Sets
We consider a scheme of equiprobable allocation of particles into cells by
sets. The Edgeworth type asymptotic expansion in the local central limit
theorem for a number of empty cells left after allocation of all sets of
particles is derived.Comment: 15 page
Measurement of (1020) meson leptonic width with CMD-2 detector at VEPP-2M Collider
The (1020) meson leptonic width has been determined from the combined
analysis of 4 major decay modes of the resonance () studied with the CMD-2 detector at
the VEPP-2M collider. The following value has been obtained:
keV.
The meson parameters in four main decay channels have been also
recalculated: , , , .Comment: 14 pages, 3 figure
Study of the radiative decay with CMD-2 detector
Using the of data collected with the CMD-2 detector at VEPP-2M
the decay mode , has been
studied. The obtained branching ratio is B(.Comment: 13 pages, 5 figures, LaTex2e, to be published in Phys. Lett.
Study of the process e+e- to pi+pi-pi+pi-pi0 with CMD-2 detector
The process e+e- to pi+ pi- pi+ pi- pi0 has been studied in the center of
mass energy range 1280 -- 1380 MeV using 3.0 1/pb of data collected with the
CMD-2 detector in Novosibirsk. Analysis shows that the cross section of the
five pion production is dominated by the contributions of the eta pi+pi- and
omega pi+pi- intermediate states.Comment: 8 pages, 3 figure. Submitted to Phys. Lett.
High-statistics measurement of the pion form factor in the rho-meson energy range with the CMD-2 detector
We present a measurement of the pion form factor based on e+e- annihilation
data from the CMD-2 detector in the energy range 0.6<sqrt(s)<1.0 GeV with a
systematic uncertainty of 0.8%. A data sample is five times larger than that
used in our previous measurement.Comment: 18 pages, 10 figures. Added comparison with KLOE measurement, minor
updates. Accepted by PL
Study of the Process in the C.M.Energy Range 1.05-1.38 GeV with CMD-2
The process has been studied with the CMD-2 detector
using about 950 events detected in the center-of-mass energy range from 1.05 to
1.38 GeV. The cross section exceeds the expectation based on the contributions
of the rho(770), omega(782) and phi(1020) mesons only.Comment: 12 pages, 3 figures, uses elsart.cls, submitted to Physics Letters
Observation of the conversion decay at CMD-2
Using 15.1^{-1} of data collected by CMD-2 in the -meson energy range,
the branching ratio of the conversion decay has been
measured for the first time: B(\phi\to\pi^0e^+e^-) = (1.22 \pm 0.34 \pm 0.21)
\cdot 10 ^{-5}.Comment: 13 pages, 6 PostScript figures, uses refmerge.sty. To be published in
Phys. Lett.
Cross section of the reaction below 1 GeV at CMD-2
Using 3.07 of data collected in the energy range 0.60-0.97 GeV by
CMD-2, about 150 events of the process \epm \to \pch have been selected. The
energy dependence of the cross section agrees with the assumption of the
intermediate state which is dominant above 1 GeV. For the first
time \fourpi events are observed at the meson energy. Under the
assumption that all these events come from the meson decay, the value of
the cross section at the meson peak corresponds to the following decay
width:
\Gamma(\rho^0 \to \fourpi) = (2.8 \pm 1.4 \pm 0.5) {keV} or to the branching
ratio
B(\rho^0 \to \fourpi) = (1.8 \pm 0.9 \pm 0.3) \cdot 10 ^{-5}.Comment: 15 pages, 5 figure
Study of the Process e+ e- --> omega pi0 --> pi0 pi0 gamma in c.m. Energy Range 920--1380 MeV at CMD-2
The cross section of the process e+ e- --> omega pi0 --> pi0 pi0 gamma has
been measured in the c.m. energy range 920-1380 MeV with the CMD-2 detector.
Its energy dependence is well described by the interference of the rho(770) and
rho'(1450) mesons decaying to omega pi0. Upper limits for the cross sections of
the direct processes e+ e- --> pi0 pi0 gamma, eta pi0 gamma have been set.Comment: Accepted for publication in PL
Spin asymmetry A_1^d and the spin-dependent structure function g_1^d of the deuteron at low values of x and Q^2
We present a precise measurement of the deuteron longitudinal spin asymmetry
A_1^d and of the deuteron spin-dependent structure function g_1^d at Q^2 < 1
GeV^2 and 4*10^-5 < x < 2.5*10^-2 based on the data collected by the COMPASS
experiment at CERN during the years 2002 and 2003. The statistical precision is
tenfold better than that of the previous measurement in this region. The
measured A_1^d and g_1^d are found to be consistent with zero in the whole
range of x.Comment: 17 pages, 10 figure
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