18 research outputs found
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
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.
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
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.
Measurement of the meson parameters with CMD-2 detector at VEPP-2M Collider
About 300 000 events in the center of mass
energy range from 984 to 1040 MeV were used for the measurement of the
meson parameters. The following results have been obtained: MeV.Comment: 13 pages, 5 figures, 5 table
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.
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
Search for rare Phi decays in pi+ pi_ gamma final state
A search for phi radiative decays has been performed using a data sample of
about 2.0 million phi decays collected by the CMD-2 detector at VEPP-2M
collider in Novosibirsk. From the selected e+ e- -> pi+ pi- gamma events the
following results were obtained: B(phi -> f0(980) gamma) < 1x10-4 for
destructive and B(phi -> f0(980) gamma) < 7x10-4 for constructive interference
with the Bremsstrahlung process respectively, B(phi -> gamma -> pi+ pi- gamma)
20 MeV, B(phi -> rho gamma) < 7x10-4. From the
selected e+ e- -> mu+ mu- gamma events B(phi -> mu+ mu- gamma) =
(2.3+-1.0)x10-5 has been obtained for E of gamma> 20 MeV. The upper limit on
the P,CP-violating decay eta -> pi+ pi- has also been placed: B(eta -> pi+ pi-)
< 9x10-4 . All upper limits are at 90 % C.L.Comment: 18 pages, 7 figure
Measurement of e+e- -> pi+pi- cross section with CMD-2 around rho-meson
The cross section of the process e+e- -> pi+pi- has been measured using about
114000 events collected by the CMD-2 detector at the VEPP-2M e+e- collider in
the center-of-mass energy range from 0.61 to 0.96 GeV. Results of the pion form
factor determination with a 0.6% systematic uncertainty are presented.
Implications for the hadronic contribution to the muon anomalous magnetic
moment are discussed.Comment: 17 pages, 4 figures, submitted to PL