Abstract
Using the 1.32
$$\hbox {pb}^{-1}$$
pb
-
1
statistics collected at the
$$J/\psi $$
J
/
ψ
peak with the KEDR detector at the VEPP-4M
$$e^{+}e^{-\, }$$
e
+
e
-
collider, we measured the ...branching fractions of
$$J/\psi $$
J
/
ψ
meson decays to the final states 2(
$$\pi ^{+}\pi ^{-})\pi ^{0}$$
π
+
π
-
)
π
0
,
$$K^{+}K^{-}\pi ^{+}\pi ^{-}\pi ^{0}$$
K
+
K
-
π
+
π
-
π
0
, 2(
$$\pi ^{+}\pi ^{-})$$
π
+
π
-
)
and
$$K^{+}K^{-}\pi ^{+}\pi ^{-}$$
K
+
K
-
π
+
π
-
. The results obtained for the decays
$$J/\psi \rightarrow $$
J
/
ψ
→
2(
$$\pi ^{+}\pi ^{-})\pi ^{0}$$
π
+
π
-
)
π
0
,
$$J/\psi \rightarrow K^{+}K^{-}\pi ^{+}\pi ^{-}\pi ^{0}$$
J
/
ψ
→
K
+
K
-
π
+
π
-
π
0
contradict the measurements performed by other groups in the last century, but agree well with recent results of BABAR and BESIII collaborations.
A
bstract
The cross section of the process
e
+
e
−
→
π
+
π
−
has been measured in the Spherical Neutral Detector (SND) experiment at the VEPP-2000
e
+
e
−
collider VEPP-2000 in the energy region 525
...<
$$ \sqrt{s} $$
s
<
883 MeV. The measurement is based on data with an integrated luminosity of about 4.6 pb
−
1
. The systematic uncertainty of the cross section determination is 0.8% at
$$ \sqrt{s} $$
s
>
0
.
600 GeV. The
ρ
meson parameters are obtained as
m
ρ
= 775
.
3 ± 0
.
5 ± 0
.
6 MeV, Γ
ρ
= 145
.
6 ± 0
.
6 ± 0
.
8 MeV,
B
ρ
→
e
+
e−
×
B
ρ
→
π
+
π−
= (4
.
89 ± 0
.
02 ± 0
.
04) × 10
−
5
, and the parameters of the
e
+
e
−
→
ω
→
π
+
π
−
process, suppressed by
G
-parity, as
B
ω
→
e
+
e−
×
B
ω
→
π
+
π−
= (1
.
32 ± 0
.
06 ± 0
.
02) × 10
−
6
and and
ϕ
ρω
= 110
.
7 ± 1
.
5 ± 1
.
0 degrees.
The singly Cabibbo-suppressed decay D+s → K + π + π − π 0 is observed by using a data set corresponding to an integrated luminosity of 6.32 fb − 1 recorded by the BESIII detector at the ...centre-of-mass energies between 4.178 and 4.226 GeV. The first amplitude analysis of D+s → K + π + π − π 0 reveals the sub-structures in this decay and determines the fractions and relative phases of different intermediate processes. The dominant intermediate process is D+s → K *0 ρ + , with a fit fraction of (40 . 5 ± 2 . 8 stat . ± 1 . 5 syst . )%. With the detection efficiency based on our amplitude analysis, the absolute branching fraction for D+s → K + π + π − π 0 is measured to be (9 . 75 ± 0 . 54 stat . ± 0 . 17 syst . ) × 10 − 3 .
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