A
bstract
We present the study of the decay
J/ψ
→
ρπ
. The results are based on of 5.2 million
J/ψ
events collected by the KEDR detector at the VEPP-4M collider. The branching fractions are measured ...to be
B
(
J/ψ
→
ρπ
) = (2
.
072 ± 0
.
017 ± 0
.
062) ∙ 10
−
2
and
B
(
J/ψ
→
π
+
π
−
π
0
) = (1
.
878 ± 0
.
013 ± 0
.
051) ∙ 10
−
2
, where the first uncertainties are statistical and the second systematic. Our results are more precise than the previous relative measurements.
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.
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.
We present the study of the decay \(J/\psi \rightarrow \rho\pi\). The results are based on of 5.2~million \(J/\psi\) events collected by the KEDR detector at the VEPP-4M collider. The branching ...fractions are measured to be \(\B(J/\psi \rightarrow \rho\pi) = \big(2.072\pm 0.017 \pm 0.062 \big)\cdot 10^{-2}\) and \(\B(J/\psi \rightarrow \pi^+\pi^-\pi^0) = \big(1.878 \pm 0.013 \pm 0.051 \big)\cdot 10^{-2}\), where the first uncertainties are statistical and the second systematic. Our results are more precise than the previous relative measurements.
The present work continues a series of the KEDR measurements of the $R$ value
that started in 2010 at the VEPP-4M $e^+e^-$ collider. By combining new data
with our previous results in this energy ...range we measured the values of
$R_{\text{uds}}$ and $R$ at nine center-of-mass energies between 3.08 and 3.72
GeV. The total accuracy is about or better than $2.6\%$ at most of energy
points with a systematic uncertainty of about $1.9\%$. Together with the
previous precise $R$ measurement at KEDR in the energy range 1.84-3.05 GeV, it
constitutes the most detailed high-precision $R$ measurement near the
charmonium production threshold.
The product of the electronic width of the $\psi(2S)$ meson and the branching
fraction of its decay to the muon pair was measured in the $e^{+}e^{-} \to
\psi(2S) \to \mu^{+}\mu^{-}$ process using ...nine data sets corresponding to an
integrated luminosity of about 6.5 pb$^{-1}$ collected with the KEDR detector
at the VEPP-4M electron-positron collider: \
\Gamma_{ee}\times\mathcal{B}_{\mu\mu} = 19.3 \pm 0.3 \pm 0.5 ~\text{eV}. \
Adding the previous KEDR results on hadronic and leptonic channels, the values
of the $\psi(2S)$ electronic width were obtained under two assumptions: either
with the assumption of lepton universality \ \Gamma_{ee} = 2.279 \pm 0.015 \pm
0.042 ~\text{keV} \ or without it, summing up hadronic and three independent
leptonic channels: \ \Gamma_{ee} = 2.282 \pm 0.015 \pm 0.042 ~\text{keV}. \
The present work continues a series of the KEDR measurements of the \(R\) value that started in 2010 at the VEPP-4M \(e^+e^-\) collider. By combining new data with our previous results in this energy ...range we measured the values of \(R_{\text{uds}}\) and \(R\) at nine center-of-mass energies between 3.08 and 3.72 GeV. The total accuracy is about or better than \(2.6\%\) at most of energy points with a systematic uncertainty of about \(1.9\%\). Together with the previous precise \(R\) measurement at KEDR in the energy range 1.84-3.05 GeV, it constitutes the most detailed high-precision \(R\) measurement near the charmonium production threshold.
The product of the electronic width of the \(\psi(2S)\) meson and the branching fraction of its decay to the muon pair was measured in the \(e^{+}e^{-} \to \psi(2S) \to \mu^{+}\mu^{-}\) process using ...nine data sets corresponding to an integrated luminosity of about 6.5 pb\(^{-1}\) collected with the KEDR detector at the VEPP-4M electron-positron collider: \ \Gamma_{ee}\times\mathcal{B}_{\mu\mu} = 19.3 \pm 0.3 \pm 0.5 ~\text{eV}. \ Adding the previous KEDR results on hadronic and leptonic channels, the values of the \(\psi(2S)\) electronic width were obtained under two assumptions: either with the assumption of lepton universality \ \Gamma_{ee} = 2.279 \pm 0.015 \pm 0.042 ~\text{keV} \ or without it, summing up hadronic and three independent leptonic channels: \ \Gamma_{ee} = 2.282 \pm 0.015 \pm 0.042 ~\text{keV}. \
