Among the observed variety of the natural phenomena reflected in experimental results, there are just a few physical features offering a view of a given fragment of the mosaic of physical laws in its ...entirety. One such remarkable fundamental feature is R, the ratio of the inclusive cross section of electron-positron annihilation into hadrons to the cross section of muon pair production in the Born approximation. We discuss experiments on measuring the R(s) ratio in the energy range 1.84-3.72 GeV.
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.
Using the KEDR detector at the VEPP-4M e+e− collider, we have determined the values of R at thirteen points of the center-of-mass energy between 1.84 and 3.05 GeV. The achieved accuracy is about or ...better than 3.9% at most of the energy points with a systematic uncertainty less than 2.4%.
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 Ruds 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.
Using the KEDR detector at the VEPP-4M e+e− collider, we have measured the values of Ruds and R at seven points of the center-of-mass energy between 3.12 and 3.72 GeV. The total achieved accuracy is ...about or better than 3.3% at most of energy points with a systematic uncertainty of about 2.1%. At the moment it is the most accurate measurement of R(s) in this energy range.
We present the analysis of all KEDR data on the determination of J/ψ and ψ(2S) masses. The data comprise six scans of J/ψ and seven scans of ψ(2S) which were performed at the VEPP-4M e+e− collider in ...2002–2008. The beam energy was determined using the resonance depolarization method. The detector and accelerator conditions during scans were very different that increases the reliability of the averaged results. The analysis accounts for partial correlations of systematic uncertainties on the masses. The following mass values were obtained:MJ/ψ=3096.900±0.002±0.006 MeV,Mψ(2S)=3686.099±0.004±0.009 MeV. These results supersede our previous measurements published in 2003 and 2012.
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.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The Super Charm-Tau Factory is an electron-positron collider project in Novosibirsk with a peak luminosity of 1035cm−1s−1 operating in the center of mass energy range between 2 and 6 GeV. The physics ...program of the experiment in general is devoted to the study of charm quark and tau lepton. Conceptual designs of the collider and a universal detector are presented. The dedicated particle identification (PID) system is required to provide the state-of-the-art level of μ/π separation for the particle momenta up to 1.2GeV/c. The following options for the PID system are considered in this paper: Focusing Aerogel RICH (FARICH) detector composed of 4-layer aerogel tiles, threshold Cherenkov counters based on aerogel and shifter (ASHIPH), Focusing DIRC (FDIRC) counter and time-of-flight (ToF) detector combined with the time-of-propagation (ToP) approach providing a time resolution better than 30ps. Also the capabilities of particles separation in tracking system are discussed. Comparison of PID approaches with help of parametric simulation is performed.
Using the 1.32
pb
-
1
statistics collected at the
J
/
ψ
peak with the KEDR detector at the VEPP-4M
e
+
e
-
collider, we measured the branching fractions of
J
/
ψ
meson decays to the final states 2(
π
...+
π
-
)
π
0
,
K
+
K
-
π
+
π
-
π
0
, 2(
π
+
π
-
)
and
K
+
K
-
π
+
π
-
. The results obtained for the decays
J
/
ψ
→
2(
π
+
π
-
)
π
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.
The available data on the DD‾ and inclusive hadronic cross sections in the ψ(3770) region from the BaBar, Belle, BES-II, CLEO and KEDR experiments have been analyzed assuming that systematic ...uncertainties on cross sections measured by various detectors are not correlated. Four theoretical models predicting the ψ(3770) line shape were considered for the DD‾ channel. All of them gave satisfactory description of the data. The combined analysis of the DD‾ and inclusive hadronic channels was performed using the model based on the vector dominance approach and accounting for the contribution of the ψ(2S) tail to the DD‾ cross section. The following values of the mass, total width, electron width and decay probability to the non-DD‾ states were obtained:M (MeV)Γ (MeV)Γee (eV)BnDD‾3779.8±0.625.8±1.3196±180.164±0.049 where the errors quoted include both statistical and dominant systematic uncertainties.
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