The dynamics of the process
e
+
e
-
→
π
+
π
-
π
0
is studied in the energy region from 1.15 to 2.00 GeV using data accumulated with the SND detector at the VEPP-2000
e
+
e
-
collider. The Dalitz plot ...distribution and
π
+
π
-
mass spectrum are analyzed in a model including the intermediate states
ρ
(
770
)
π
,
ρ
(
1450
)
π
, and
ω
π
0
. As a result, the energy dependences of the
ρ
(
770
)
π
and
ρ
(
1450
)
π
cross sections and the relative phases between the
ρ
(
770
)
π
amplitude and the
ρ
(
1450
)
π
and
ω
π
0
amplitudes are obtained. The
ρ
(
1450
)
π
cross section has a peak in the energy region of the
ω
(
1650
)
resonance (1.55–1.75 GeV). In this energy range the contributions of the
ρ
(
770
)
π
and
ρ
(
1450
)
π
states are of the same order of magnitude. No resonance structure near 1.65 GeV is observed in the
ρ
(
770
)
π
cross section. We conclude that the intermediate state
ρ
(
1450
)
π
gives a significant contribution to the decay of
ω
(
1650
)
→
π
+
π
-
π
0
, whereas the
ρ
(
770
)
π
mechanism dominates in the decay
ω
(
1420
)
→
π
+
π
-
π
0
.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The process
e
+
e
-
→
η
π
0
γ
is studied in the center-of-mass energy range 1.05–2.00 GeV using data with an integrated luminosity of 94.5
pb
-
1
collected by the SND detector at the VEPP-2000
e
+
e
...-
collider. The
e
+
e
-
→
η
π
0
γ
cross section is measured for the first time. It is shown that the dominant mechanism of this reaction is the transition through the
ω
η
intermediate state. The measured cross section of the subprocess
e
+
e
-
→
ω
η
→
η
π
0
γ
is consistent with previous measurements in the
e
+
e
-
→
π
+
π
-
π
0
η
mode. It is found, with a significance of
5.6
σ
, that the process
e
+
e
-
→
η
π
0
γ
is not completely described by hadronic vector-pseudoscalar intermediate states. The cross section of this missing contribution, which can originate from radiation processes, e. g.
e
+
e
-
→
a
0
(
1450
)
γ
, is measured. It is found to be 15–20 pb in the wide energy range from 1.3 to 1.9 GeV.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The VEPP-2000 electron–positron collider has been operating at the Budker Institute of Nuclear Physics (BINP) since 2010. Applying the concept of round colliding beams allowed the record value of the ...beam–beam parameter ξ ∼ 0.12 to be reached. The upgrading of the VEPP-2000 complex, including the connection to the new BINP Injection Complex and modification of the electron–position booster and the BEP–VEPP-2000 transfer channels to work at 1 GeV, resulted in a significant increase in luminosity. Work on statistical data collection using detectors is in progress.
A search for the process
e
+
e
−
→
D
*0
(2007) has been performed with the CMD-3 detector at the VEPP-2000
e
+
e
−
-collider. Two main decay modes of the
D
*0
(2007) decay,
D
0
π
0
and
D
0
γ, ...followed by
D
0
→
K
+
π
−
π
+
π
−
are used in this analysis. With an integrated luminosity of 3.7 pb
−1
collected at the center-of-mass energy E
c.m.
=2006.62 MeV our preliminary upper limit is B
D*
0
→
e
+
e
−
<1.6× 10
−6
at 90%C.L.
The cross section of the process
e
+
e
−
→ π
+
π
−
π
+
π
−
has been measured using an integrated luminosity of 17 pb
−1
collected with the CMD-3 detector in the center-of-mass energy range 650-1000 ...MeV. High-precision measurements of various hadronic cross sections are of great interest in relation with the problem of the muon anomalous magnetic moment g-2. This measurement can be also used to test the relation between the cross section of
e
+
e
−
→ π
+
π
−
π
+
π
−
and the spectral function for the τ
−
→ π
−
π
0
π
0
π
0
decay predicted by the conservation of vector current (CVC).
A recent result of the cross section measurement of the process e + e − → K S K π at e + e − collider VEPP-2000 is presented using a data sample of the ∼150 pb−1 integrated luminosity collected with ...the CMD-3 detector. The processes with charged kaons in multi hadron events attract special interest, because they impact strongly on studies of light quark hadronization, isospin symmetry, and strange meson spectroscopy. Experimental results of e + e − → K S K π cross section are presented in a broad energy range covered by the VEPP-2000 and compared to earlier measurements. A study of the production dynamics confirms the dominance of neutral KK * ( 892 ) intermediate state.
The cross sections , , , , K+K−, , , have been measured with the spherical neutral detector at the VEPP-2000 e+e− collider in the energy range from 0.3 to 2.0 GeV.
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