We have reconsidered the results on the masses of the narrow bottomonium states ϒ(1S)–ϒ(3S) obtained in 1982–1986 at CESR, DORIS and VEPP-4 colliders in order to fix shortcomings of the mass ...determination procedures. For experiments at CESR and DORIS this includes the incorrect accounting of the radiative corrections and usage of the electron mass value revised in 1986. In analyses of all experiments the interference of the resonance production and the nonresonant process was ignored. The corrected mass values for five experiments are suggested. The corrections vary from 0.1 to 0.4 MeV. The discrepancy between CESR and VEPP-4 results on ϒ(1S) mass has been reduced from 3.3 to 1.8 standard deviations.
The tagging system of the KEDR detector for the two-photon studies is briefly described. The procedure of the energy calibration of the system is considered. Two-photon events e+e− e+e−+μ+μ− selected ...with the central detector were employed to check the energy calibration and to measure the tagging efficiencies. The results obtained demonstrate that the achieved accuracy of the energy calibration is about 1%. To improve the accuracy to the level of 0.3% the upgrade of the calibration system is ongoing. The tagging efficiencies obtained with the simulation agree with the measured one within the error of the measurement.
An extension of BDK event generator Krachkov, P. A.; Milstein, A. I.; Rezanova, O. L. ...
EPJ Web of Conferences,
2019, Letnik:
212
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
An extension of the well known
ee
→ 4
l
event generator of F. A. Berends, P. H. Daverveldt, and R. Kleiss is presented. This extension accounts for production of narrow resonances, as well as the ...initial state radiation. In addition, it allows one to simulate the production of
l
+
l
−
π
+
π
−
with the lepton pair and the pion pair in 1
−−
states.
The
e
+
e
−
→
e
+
e
−
+ μ
+
μ
−
events selected in the central part of the KEDR detector are used for testing the energy calibration of the scattered electron tagging system and estimating the ...efficiencies for tagging one and two scattered electrons as a function of the virtual photon energy.
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 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.
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 KEDR Tagging System is designed to enhance the detector ability to study the two-photon processes e super(+)e super(-) arrow right e super(+)e super(-)X. The collider magnetic elements (dipoles ...and lenses) form a focusing magnetic spectrometer for the Scattered Electrons and positrons (for brevity SE). Its energies are measured with 8 coordinate blocks which are placed beside of the vacuum chamber. In the double-tag mode (when both SE are detected) an invariant mass of the system X can be measured with the resolution 3-15 MeV for W sub(inv)(X) = 300 4- 4000 MeV depending on the W and the beam energy. The changes of the beam energy produce some changes in the magnetic structure and the beam orbit. These changes cause systematic shifts of the measured SE energy in TS blocks. The shifts leads to degradation of the W sub(inv)(X) resolution. The complex calibration system was constructed to allow the calibration for all TS blocks with the necessary accuracy.
Measurement of Γee(J/ψ) with KEDR detector Anashin, V. V; Aulchenko, V. M; Baldin, E. M ...
The journal of high energy physics,
05/2018, Letnik:
2018, Številka:
5
Journal Article
Recenzirano
Odprti dostop
A
bstract
The product of the electronic width of the
J/ψ
meson and the branching fractions of its decay to hadrons and electrons has been measured using the KEDR detector at the VEPP-4M
e
+
e
−
...collider. The obtained values are
Γ
e
e
J
/
ψ
=
5.550
±
0.056
±
0.089
keV
,
Γ
e
e
J
/
ψ
·
ℬ
hadrons
J
/
ψ
=
4.884
±
0.048
±
0.078
keV
,
Γ
e
e
J
/
ψ
·
ℬ
e
e
J
/
ψ
=
0.3331
±
0.0066
±
0.0040
keV
.
The uncertainties shown are statistical and systematic, respectively. Using the result presented and the world-average value of the electronic branching fraction, one obtains the total width of the
J/ψ
meson:
Γ
=
92.94
±
1.83
keV
.
These results are consistent with the previous experiments.
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
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