51 research outputs found
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.
Observation of semileptonic decays with CMD-2 detector
The decay has been observed by the CMD-2 detector at
the e^+e^- collider VEPP-2M at Novosibirsk. Of 6 million produced
pairs, events of the decay were selected. The
corresponding branching ratio is . This result is consistent with the evaluation of from the semileptonic rate and lifetime
assuming .Comment: 7 pages, 6 figures, LaTex2e. Submitted to Phys.Lett.
Measurement of omega meson parameters in pi^+pi^-pi^0 decay mode with CMD-2
About 11 200 e^+e^- -> omega -> pi^+pi^-pi^0 events selected in the center of
mass energy range from 760 to 810 MeV were used for the measurement of the
\omega meson parameters. The following results have been obtained: sigma
_{0}=(1457 \pm 23 \pm 19)nb, m_{\omega}=(782.71 \pm 0.07 \pm 0.04) MeV/c^{2},
\Gamma_{\omega}=(8.68 \pm 0.23 \pm 0.10) MeV,
\Gamma_{e^+e^-}\cdot Br (\omega -> pi^+pi^-pi^0)=
(0.528 \pm 0.012 \pm 0.007) \cdot 10^{-3} MeV.Comment: 8 pages, 4 figure
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- 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.
Study of KS KL Coupled Decays and KL -Be Interactions with the CMD-2 Detector at VEPP-2M Collider
The integrated luminosity about 4000 inverse nanobarn of around phi meson
mass ( 5 millions of phi mesons) has been collected with the CMD-2 detector at
the VEPP-2M collider. A latest analysis of the KS KL coupled decays based on 30
% of available data is presented in this paper.
The KS KL pairs from phi meson decays were reconstructed in the drift chamber
when both kaons decayed into two charged particles. From a sample of 1423
coupled decays a selection of candidates to the CP violating KL into pi+ pi-
decay was performed. CP violating decays were not identified because of the
domination of events with a KL regenerating at the Be beam pipe into KS and a
background from KL semileptonic decays.
The regeneration cross section of 110 MeV/c KL mesons was found to be 53 +-
17 mb in agreement with theoretical expectations. The angular distribution of
KS mesons after regeneration and the total cross section of KL for Be have been
measured.Comment: 14 pages, 8 figure
First observation of the decay
Radiative decays of the meson have been studied using a data sample of
about 20 million decays collected by the CMD-2 detector at VEPP-2M
collider in Novosibirsk. From selected events
the decay has been observed for the first time.
\par Under the assumption that the intermediate state
dominates in the decay, the corresponding branching
ratio is .
\par Selected events were used to obtain
for
MeV. \par Using the same data sample, upper limits at 90% CL
have been obtained for the C-violating decay of the :
; and for the P- and CP-violating
decay of the : \par .Comment: 16 pages, 10 figures, Submitted to Phys. Lett.
Study of the decays into and final states
Radiative decays of the meson have been studied using a data sample of
about 19 million decays collected by the CMD-2 detector at VEPP-2M
collider in Novosibirsk. From selected and
events the following model independent results
have been obtained: \par for MeV, \par
.
It is shown that the intermediate mechanism dominates in
the decay and the corresponding branching ratio
is \par . The
systematic error is dominated by the possible model uncertainty. \par Using the
same data sample the upper limit has been obtained for the P- and CP-violating
decay of at 90% CL: \par
>.Comment: 13 pages, 6 figures, Submitted to Phys. Lett.
Study of the Process e+ e- ---> eta gamma in c.m. Energy Range 600-1380 MeV at CMD-2
The cross section of the process e+ e- ---> eta gamma has been measured in
the 600-1380 MeV c.m. energy range with the CMD-2 detector. The following
branching ratios have been determined:
B(rho ---> eta gamma) = (3.28 +- 0.37 +- 0.23) 10^{-4},
B(omega ---> eta gamma) = (5.10 +- 0.72 +- 0.34) 10^{-4},
B(phi --> eta gamma) = (1.287 +- 0.013 +- 0.063) 10^{-2}.
Evidence for the rho'(1450) ---> eta gamma decay has been obtained for the
first time.Comment: 17pages, 4 figures, submited to Phys.Lett.
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