-
O. V. Anchugov,
V. E. Blinov,
A. V. Bogomyagkov,
A. A. Volkov,
A. N. Zhuravlev,
S. E. Karnaev,
V. A. Kiselev,
E. B. Levichev,
O. I. Meshkov,
S. I. Mishnev, [......], E. A. Simonov,
S. V. Sinyatkin,
A. N. Skrinskii,
V. V. Smaluk,
Yu. A. Tikhonov,
G. M. Tumaikin,
V. M. Tsukanov,
A. G. Shamov,
D. N. Shatilov,
D. A. Shvedov
[show abstract]
[hide abstract]
ABSTRACT: Based on precision measurements of the beam energy using the resonant depolarization and Compton backscattering methods, it
is possible to conduct high-precision experiments in the field of high-energy physics at the VEPP4M electron-positron collider
with the KEDR detector. The J/ψr- and ψ(2s)-meson masses measured at the VEPP4M collider ar e among the ten most precisely
known masses of elementary particles measured over the whole physical history. The degree of accuracy that we attained in
determining theτlepton mass by the threshold behavior of the e+e- τ+τ reaction cross section is the best in the world. Systems
automatically controlling the temperature of the distillate that cools the magnets of the main accelerating structure and
the RF accelerating cavities of the VEPP4M collider have been developed, produced, and placed in operation in order to increase
the efficiency of the complex. Simultaneous measurements of the transverse displacement and the angle of inclination of the
beam near the interaction point can be taken with the aid of a multipinhole X-ray camera.
Instruments and Experimental Techniques 04/2012; 53(1):15-28. · 0.36 Impact Factor
-
O. V. Anchugov,
V. E. Blinov,
A. V. Bogomyagkov,
A. N. Zhuravlev,
S. E. Karnaev,
G. V. Karpov,
V. A. Kiselev,
G. Ya. Kurkin,
E. B. Levichev,
O. I. Meshkov, [......], E. A. Simonov,
S. V. Sinyatkin,
A. N. Skrinsky,
V. V. Smaluk,
Yu. A. Tikhonov,
G. M. Tumaikin,
A. G. Shamov,
D. N. Shatilov,
D. A. Shvedov,
E. I. Shubin
[show abstract]
[hide abstract]
ABSTRACT: The VEPP-4M accelerator facility with a universal KEDR detector is designed to conduct experiments with colliding electron-positron
beams. High-energy physics, nuclear physics, and studies using synchrotron radiation are the main directions of research with
this facility. In addition, experiments on poorly explored issues in the physics of beams in the electron-positron storage
ring and methodological studies to prepare an experiment aimed at testing corollaries of the CPT theorem for an electron and
a positron are regularly conducted at the VEPP-4 facility. A number of works performed in recent years are described: studies
to increase the accuracy of comparing the electron and positron spin precession frequencies by the resonant depolarization
method; measurements of the count rate of Touschek electrons as a function of the beam energy in a wide range; comparison
of the methods for measuring the beam energy spread; a study of the electron beam dynamics when a nonlinear betatron resonance
is crossed.
Journal of Experimental and Theoretical Physics 04/2012; 109(4):590-601. · 1.03 Impact Factor
-
V. V. Anashin,
V. M. Aulchenko,
E. M. Baldin,
A. K. Barladyan,
A. Yu. Barnyakov,
M. Yu. Barnyakov,
S. E. Baru,
I. Yu. Basok,
O. L. Beloborodova,
A E Blinov, [......],
V I Telnov,
Yu. A. Tikhonov,
K. Yu. Todyshev,
G. M. Tumaikin,
Yu. V. Usov,
A. I. Vorobiov,
A N Yushkov,
V. N. Zhilich,
V. V. Zhulanov,
A. N. Zhuravlev
[show abstract]
[hide abstract]
ABSTRACT: We report a new precise determination of the leptonic widths of the J/psi
meson performed with the KEDR detector at the VEPP-4M $e^{+}e^{-}$ collider.
The measured values of the J/psi parameters are:
\Gamma_{ee}\times\Gamma_{ee}/\Gamma = 0.3323 \pm 0.0064 (stat.) \pm 0.0048
(syst.) keV \Gamma_{ee}\times\Gamma_{\mu\mu}/\Gamma=0.3318 \pm 0.0052 (stat.)
\pm 0.0063 (syst.) keV. Assuming $e\mu$ universality and using the table value
of the branching ratios the leptonic \Gamma_{ll}= 5.59 \pm 0.12 keV width and
the total \Gamma=94.1 \pm 2.7 keV widths were obtained. We also discuss in
detail a method to calculate radiative corrections at a narrow resonance.
10/2011;
-
V. V. Anashin,
V. M. Aulchenko,
E. M. Baldin,
A. K. Barladyan,
A. Yu. Barnyakov,
M. Yu. Barnyakov,
S. E. Baru,
I. Yu. Basok,
O. L. Beloborodova,
A. E. Blinov, [......],
V. I. Telnov,
Yu. A. Tikhonov,
K. Yu. Todyshev,
G. M. Tumaikin,
Yu. V. Usov,
A. I. Vorobiov,
A. N. Yushkov,
V. N. Zhilich,
V. V. Zhulanov,
A. N. Zhuravlev
[show abstract]
[hide abstract]
ABSTRACT: We report the final results of a study of the \psi(3770) meson using a data
sample collected with the KEDR detector at the VEPP-4M electron-positron
collider. The data analysis takes into account the interference between the
resonant and nonresonant $D\bar{D}$ production, where the latter is related to
the nonresonant part of the energy-dependent form factor $F_D$. The vector
dominance approach and several empirical parameterizations have been tried for
the nonresonant $F_D^{\NR}(s)$.
Our results for the mass and total width of \psi(3770) are
M = 3779.2 ^{+1.8}_{-1.7} ^{+0.5}_{-0.7} ^{+0.3}_{-0.3} MeV, \Gamma =24.9
^{+4.6}_{-4.0} ^{+0.5}_{-0.6} ^{+0.2}_{-0.9} MeV, where the first, second and
third uncertainties are statistical, systematic and model, respectively. For
the electron partial width two possible solutions have been found:
(1) \Gamma_{ee} = 154 ^{+79}_{-58} ^{+17}_{-9} ^{+13}_{-25} eV, (2)
\Gamma_{ee} = 414 ^{+72}_{-80} ^{+24}_{-26} ^{+90}_{-10} eV.
Our statistics are insufficient to prefer one solution to another. The
solution (2) mitigates the problem of non-$D\bar{D}$ decays but is disfavored
by potential models.
It is shown that taking into account the resonance--continuum interference in
the near-threshold region affects resonance parameters, thus the results
presented can not be directly compared with the corresponding PDG values
obtained ignoring this effect.
09/2011;
-
V. V. Anashin,
V. M. Aulchenko,
E. M. Baldin,
A. K. Barladyan,
A. Yu. Barnyakov,
M. Yu. Barnyakov,
S. E. Baru,
I. Yu. Basok,
O. L. Beloborodova,
A. E. Blinov, [......],
V. I. Telnov,
Yu. A. Tikhonov,
K. Yu. Todyshev,
G. M. Tumaikin,
Yu. V. Usov,
A. I. Vorobiov,
A. N. Yushkov,
V. N. Zhilich,
V. V. Zhulanov,
A. N. Zhuravlev
[show abstract]
[hide abstract]
ABSTRACT: A high-precision determination of the main parameters of the \psi(2S)
resonance has been performed with the KEDR detector at the VEPP-4M e^{+}e^{-}
collider in three scans of the \psi(2S) -- \psi(3770) energy range. Fitting the
energy dependence of the multihadron cross section in the vicinity of the
\psi(2S) we obtained the mass value
M = 3686.114 +- 0.007 +- 0.011 ^{+0.002}_{-0.012} MeV and the product of the
electron partial width by the branching fraction into hadrons \Gamma_{ee}*B_{h}
= 2.233 +- 0.015 +- 0.037 +- 0.020 keV.
The third error quoted is an estimate of the model dependence of the result
due to assumptions on the interference effects in the cross section of the
single-photon e^{+}e^{-} annihilation to hadrons explicitly considered in this
work.
Implicitly, the same assumptions were employed to obtain the charmonium
leptonic width and the absolute branching fractions in many experiments.
Using the result presented and the world average values of the electron and
hadron branching fractions, one obtains the electron partial width and the
total width of the \psi(2S):
\Gamma_{ee} =2.282 +- 0.015 +- 0.038 +- 0.021 keV,
\Gamma = 296 +- 2 +- 8 +- 3 keV.
These results are consistent with and more than two times more precise than
any of the previous experiments.
09/2011;
-
KEDR Collaboration,
V. V. Anashin,
V. M. Aulchenko,
E. M. Baldin,
A. K. Barladyan,
A. Yu. Barnyakov,
M. Yu. Barnyakov,
S. E. Baru,
I. Yu. Basok,
O. L. Beloborodova, [......],
V I Telnov,
Yu. A. Tikhonov,
K. Yu. Todyshev,
G. M. Tumaikin,
Yu. V. Usov,
A. I. Vorobiov,
A N Yushkov,
V. N. Zhilich,
V. V. Zhulanov,
A. N. Zhuravlev
[show abstract]
[hide abstract]
ABSTRACT: We report results of a search for narrow resonances in e+ e- annihilation at
center-of-mass energies between 1.85 and 3.1 GeV performed with the KEDR
detector at the VEPP-4M e+ e- collider. The upper limit on the leptonic width
of a narrow resonance Gamma(R -> ee) Br(R -> hadr) < 120 eV has been obtained
(at 90 % C.L.).
07/2011;
-
V. V. Anashin,
V. M. Aulchenko,
E. M. Baldin,
A. K. Barladyan,
A. Yu. Barnyakov,
M. Yu. Barnyakov,
S. E. Baru,
I. Yu. Basok,
I. V. Bedny,
O. L. Beloborodova, [......],
V I Telnov,
Yu. A. Tikhonov,
K. Yu. Todyshev,
G. M. Tumaikin,
Yu. V. Usov,
A. I. Vorobiov,
A N Yushkov,
V. N. Zhilich,
V. V. Zhulanov,
A. N. Zhuravlev
[show abstract]
[hide abstract]
ABSTRACT: We present a study of the inclusive photon spectrum from 6.3 million J/psi decays collected with the KEDR detector at the VEPP-4M e+e- collider. We measure the branching fraction of the radiative decay J/psi -> eta_c gamma, eta_c width and mass. Taking into account an asymmetric photon line shape we obtain: M(eta_c) = (2978.1 +- 1.4 +- 2.0) MeV/c^2, Gamma(eta_c) = (43.5 +- 5.4 +- 15.8) MeV, B(J/psi->eta_c gamma) = (2.59 +- 0.16 +- 0.31)%$. Comment: 6 pages, 1 figure. To be published in the proceedings of the 4th International Workshop on Charm Physics (Charm2010), October 21-24, 2010, IHEP, Beijing
12/2010;
-
V. V. Anashin,
V. M. Aulchenko,
E. M. Baldin,
A. K. Barladyan,
A. Yu. Barnyakov,
M. Yu. Barnyakov,
S. E. Baru,
I. V. Bedny,
O. L. Beloborodova,
A. E. Blinov, [......],
V. I. Telnov,
Yu. A. Tikhonov,
K. Yu. Todyshev,
G. M. Tumaikin,
Yu. V. Usov,
A. I. Vorobiov,
A. N. Yushkov,
V. N. Zhilich,
V. V. Zhulanov,
A. N. Zhuravlev
[show abstract]
[hide abstract]
ABSTRACT: We present a study of the inclusive photon spectra from 5.9 million J/ψ decays collected with the KEDR detector at the VEPP-4M e+e− collider. We measure the branching fraction of radiative decay J/ψ → ηcγ, ηc width and mass. Our preliminary results are: M(ηc) = 2979.4±1.5±1.9 MeV/c2, Γ(ηc) = 27.8±5.1±3.3 MeV, Γ(J/ψ→ ηcγ) = (2.34±0.15±0.40)%.
Chinese Physics C 06/2010; 34(6):831. · 0.27 Impact Factor
-
V. V. Anashin,
V. M. Aulchenko,
E. M. Baldin,
A. K. Barladyan,
A. Yu. Barnyakov,
M. Yu. Barnyakov,
S. E. Baru,
I. V. Bedny,
O. L. Beloborodova,
A. E. Blinov, [......],
Yu. A. Tikhonov,
K. Yu. Todyshev,
G. M. Tumaikin,
Yu. V. Usov,
A. I. Vorobiov,
A. N. Yushkov,
V. N. Zhilich,
V. V. Zhulanov,
A. N. Zhuravlev,
KEDR Collaboration
[show abstract]
[hide abstract]
ABSTRACT: The products of the electron width of the J/ψ meson and the
branching fraction of its decays to the lepton pairs were measured using
data from the KEDR experiment at the VEPP-4M electron-positron collider.
The results are
Γ×Γ/Γ=0.3323±0.0064(stat.)±0.0048(syst.)
keV,
Γ×Γ/Γ=0.3318±0.0052(stat.)±0.0063(syst.)
keV. Their combinations
Γ×(Γ+Γ)/Γ=0.6641±0.0082(stat.)±0.0100(syst.)
keV,
Γ/Γ=1.002±0.021(stat.)±0.013(syst.)
can be used to improve the accuracy of the leptonic and full widths and
test leptonic universality. Assuming eμ universality and using the
world average value of the lepton branching fraction, we also determine
the leptonic Γ=5.59±0.12 keV and total
Γ=94.1±2.7 keV widths of the J/ψ meson.
Physics Letters B 02/2010; 685:134-140. · 3.95 Impact Factor
-
V. V. Anashin,
V. M. Aulchenko,
E. M. Baldin,
A. K. Barladyan,
A. Yu. Barnyakov,
M. Yu. Barnyakov,
S. E. Baru,
I. V. Bedny,
O. L. Beloborodova,
A E Blinov, [......],
V I Telnov,
Yu. A. Tikhonov,
K. Yu. Todyshev,
G. M. Tumaikin,
Yu. V. Usov,
A. I. Vorobiov,
A N Yushkov,
V. N. Zhilich,
V. V. Zhulanov,
A. N. Zhuravlev
[show abstract]
[hide abstract]
ABSTRACT: We present a study of the inclusive photon spectra from 5.9 million J/psi decays collected with the KEDR detector at the VEPP-4M e+e- collider. We measure the branching fraction of radiative decay J/psi to eta_c gamma, eta_c width and mass. Our preliminary results are: M(eta_c) = 2979.4+-1.5+-1.9 MeV, G(eta_c) = 27.8+-5.1+-3.3 MeV, B(J/psi to eta_c gamma) = (2.34+-0.15+-0.40)%. Comment: To be published in Proceedings of the PhiPsi09, Oct. 13-16, 2009, Beijing, China
02/2010;
-
V. V. Anashin,
V. M. Aulchenko,
E. M. Baldin,
A. K. Barladyan,
A. Yu. Barnyakov,
M. Yu. Barnyakov,
S. E. Baru,
I. V. Bedny,
O. L. Beloborodova,
A E Blinov, [......],
V I Telnov,
Yu. A. Tikhonov,
K. Yu. Todyshev,
G. M. Tumaikin,
Yu. V. Usov,
A. I. Vorobiov,
A N Yushkov,
V. N. Zhilich,
V. V. Zhulanov,
A. N. Zhuravlev
[show abstract]
[hide abstract]
ABSTRACT: We report results of experiments performed with the KEDR detector at the VEPP-4M e+e- collider. They include precise measurement of the D0 and D+- meson masses, determination of the psi(3770) resonance parameters, and a search for narrow resonances in e+e- annihilation at center-of-mass energies between 1.85 and 3.1 GeV. Comment: To be published in Proceedings of the PhiPsi09, Oct. 13-16, 2009, Beijing, China
01/2010;
-
KEDR Collaboration,
V. V. Anashin,
V. M. Aulchenko,
E. M. Baldin,
A. K. Barladyan,
A. Yu. Barnyakov,
M. Yu. Barnyakov,
S. E. Baru,
I. V. Bedny,
O. L. Beloborodova, [......],
V I Telnov,
Yu. A. Tikhonov,
K. Yu. Todyshev,
G. M. Tumaikin,
Yu. V. Usov,
A. I. Vorobiov,
A N Yushkov,
V. N. Zhilich,
V. V. Zhulanov,
A. N. Zhuravlev
[show abstract]
[hide abstract]
ABSTRACT: The products of the electron width of the J/\psi meson and the branching fraction of its decays to the lepton pairs were measured using data from the KEDR experiment at the VEPP-4M electron-positron collider. The results are \Gamma_{ee}(J/\psi)*Br(J/\psi->e^+e^-)=(0.3323\pm0.0064\pm0.0048) keV, \Gamma_{ee}(J/\psi)*Br(J/\psi->\mu^+\mu^-)=(0.3318\pm0.0052\pm0.0063) keV. Their combinations \Gamma_{ee}\times(\Gamma_{ee}+\Gamma_{\mu\mu})/\Gamma=(0.6641\pm0.0082\pm0.0100) keV, \Gamma_{ee}/\Gamma_{\mu\mu}=1.002\pm0.021\pm0.013 can be used to improve theaccuracy of the leptonic and full widths and test leptonic universality. Assuming e\mu universality and using the world average value of the lepton branching fraction, we also determine the leptonic \Gamma_{ll}=5.59\pm0.12 keV and total \Gamma=94.1\pm2.7 keV widths of the J/\psi meson. Comment: 7 pages, 6 figures
12/2009;
-
V. V. Anashin,
V. M. Aulchenko,
E. M. Baldin,
A. K. Barladyan,
A. Yu. Barnyakov,
M. Yu. Barnyakov,
S. E. Baru,
I. V. Bedny,
O. L. Beloborodova,
A. E. Blinov, [......],
V. A. Tayursky,
V. I. Telnov,
Yu. A. Tikhonov,
K. Yu. Todyshev,
G. M. Tumaikin,
Yu. V. Usov,
A. I. Vorobiov,
A. N. Yushkov,
V. N. Zhilich,
A. N. Zhuravlev
[show abstract]
[hide abstract]
ABSTRACT: A precise τ lepton mass measurement performed at the VEPP-4M collider with the KEDR detector is reported. The mass value is
evaluated from the τ+τ− cross section behavior around the production threshold. The result based on 6.7 pb−1 of data is m
τ = 1776.81
−0.23
+0.25
± 0.15 MeV. Using 0.8 pb−1 of data collected at the ψ′ peak, we have also determined that Γ
ee
B
ττ(ψ′) = 9.0 ± 2.6 eV.
JETP Letters 05/2007; 85(8):347-352. · 1.35 Impact Factor
-
Sh Zh Akhmadaliev,
G Ya Kezerashvili,
S G Klimenko,
R N Lee,
V M Malyshev,
A L Maslennikov,
A M Milov,
A I Milstein,
N Yu Muchnoi,
A I Naumenkov,
V S Panin,
S V Peleganchuk,
G E Pospelov,
I Ya Protopopov,
L V Romanov,
A G Shamov,
D N Shatilov, E A Simonov,
V M Strakhovenko,
Yu A Tikhonov
[show abstract]
[hide abstract]
ABSTRACT: Data analysis of an experiment in which photon splitting in atomic fields was observed is presented. The experiment was performed at the tagged photon beam of the ROKK-1M facility at the VEPP-4M collider. In the energy region of 120-450 MeV, statistics of 1.6x10(9) photons incident on the BGO target was collected. About 400 candidate photon-splitting events were reconstructed. Within the attained experimental accuracy, the experimental results are consistent with the calculated exact atomic-field cross section. The predictions obtained in the Born approximation differ significantly from the experimental results.
Physical Review Letters 09/2002; 89(6):061802. · 7.37 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Quasi-monochromatic photon beams of 108 MeV Compton-edge energy produced in the ROKK-1M facility at the storage ring VEPP-4M (BINP, Novosibirsk) and makrofol sheets as fission track detectors were used to measure the photofission yield of 27Al. The fission yield was found to be (160±55) µb. From this result and previously measured 27Al photofission yield at ~79 MeV end-point energy with the LADON apparatus, the trends of fission cross section and fissility have been obtained in the incident photon energy range ~40-110 MeV. The present results and data for other intermediate-mass nuclei obtained with the same methodology indicate an increase of fissility with decreasing Z2/A as predicted by the liquid drop model for fissioning systems lighter than ~Ag.
Journal of Physics G Nuclear and Particle Physics 09/1999; 25(9):1979. · 4.18 Impact Factor
-
M L Terranova,
G Ya Kezerashvili,
A M Milov,
S I Mishnev,
N Yu Muchnoi,
A I Naumenkov,
I Ya Protopopov, E A Simonov,
D N Shatilov,
O A P Tavares,
E De Paiva,
E L Moreira
[show abstract]
[hide abstract]
ABSTRACT: Cross section measurements for photofission induced in , , , and by 120 and 145 MeV quasi-monochromatic photon beams have been performed at the ROKK-1M facility (BINP, Novosibirsk). The fission yields have been obtained using Makrofol sheets as solid-state fission track detectors. Nuclear fissility values have been deduced on the basis of Levinger's modified quasi-deuteron model of photonuclear interaction, and compared with available literature data. The trend of fissility in the 60-145 MeV energy range has been analysed for various target nuclei as a function of energy and of the parameter .
Journal of Physics G Nuclear and Particle Physics 12/1998; 24(1):205. · 4.18 Impact Factor
-
M L Terranova,
O A P Tavares,
G Ya Kezerashvili,
V A Kiselev,
A M Milov,
N Yu Muchnoi,
A I Naumenkov,
V V Petrov,
I Ya Protopopov, E A Simonov,
E de Paiva,
E L Moreira
[show abstract]
[hide abstract]
ABSTRACT: Photofission cross sections of and nuclei have been measured at an incident photon energy of 100 MeV using monochromatic photons produced by Compton backscattering at the ROKK-1M facility (BINP, Novosibirsk). Detection of fission fragments has been performed by means of Makrofol track-etch detectors in close contact with metallic foils of the target elements. The values of fissility at 100 MeV deduced for the targets under investigation are found to range between and . The present results show consistency with the fissility trends calculated for 69 and 600 MeV monoenergetic photons using a formalism based on the current two-step model for intermediate-energy photofission reactions.
Journal of Physics G Nuclear and Particle Physics 12/1998; 22(4):511. · 4.18 Impact Factor
-
Sh. Zh. Akhmadaliev,
G. Ya. Kezerashvili,
S. G. Klimenko,
V. M. Malyshev,
A. L. Maslennikov,
A. M. Milov,
A. I. Milstein,
N. Yu. Muchnoi,
A. I. Naumenkov,
V. S. Panin,
S. V. Peleganchuk,
V. G. Popov,
G. E. Pospelov,
I. Ya. Protopopov,
L. V. Romanov,
A. G. Shamov,
D. N. Shatilov, E. A. Simonov,
Yu. A. Tikhonov
[show abstract]
[hide abstract]
ABSTRACT: The differential cross section of Delbrück scattering is measured
on a bismuth germanate (Bi4Ge3O12)
target at photon energies 140-450 MeV and scattering angles 2.6-16.6
mrad. A good agreement with the theoretical results, obtained exactly in
a Coulomb field, is found.
Physical Review C 10/1998; 58:2844-2850. · 3.31 Impact Factor
-
SH. ZH. Akhmadaliev,
G. Ya. Kezerashvili,
S G Klimenko,
V. M. Malyshev,
A L Maslennikov,
A. M. Milov,
A. I. Milstein,
N. Yu. Muchnoi,
A. I. Naumenkov,
V S Panin,
S.V. Peleganchuk,
V. G. Popov,
G.E. Pospelov,
I Ya Protopopov,
L. V. Romanov,
A. G. Shamov,
D. N. Shatilov, E. A. Simonov,
Yu. A. Tikhonov
[show abstract]
[hide abstract]
ABSTRACT: The differential cross section of Delbr\"{u}ck scattering is measured on a bismuth germanate $Bi_4Ge_3O_{12}$ target at photon energies $140 - 450 MeV$ and scattering angles $2.6 - 16.6 mrad$. A good agreement with the theoretical results, obtained exactly in a Coulomb field, is found. Comment: 6 pages, revtex, 12 figures, 2 tables
06/1998;
-
V.V. Anashin,
V.M. Aulchenko,
E.M. Baldin,
A.K. Barladyan,
A.Yu. Barnyakov,
M.Yu. Barnyakov,
S.E. Baru,
I.V. Bedny,
O.L. Beloborodova,
A.E. Blinov, [......],
V.I. Telnov,
Yu.A. Tikhonov,
K.Yu. Todyshev,
G.M. Tumaikin,
Yu.V. Usov,
A.I. Vorobiov,
A.N. Yushkov,
V.N. Zhilich,
V.V. Zhulanov,
A.N. Zhuravlev
[show abstract]
[hide abstract]
ABSTRACT: The products of the electron width of the J/ψ meson and the branching fraction of its decays to the lepton pairs were measured using data from the KEDR experiment at the VEPP-4M electron–positron collider. The results areΓee×Γee/Γ=0.3323±0.0064(stat.)±0.0048(syst.) keV,Γee×Γμμ/Γ=0.3318±0.0052(stat.)±0.0063(syst.) keV. Their combinationsΓee×(Γee+Γμμ)/Γ=0.6641±0.0082(stat.)±0.0100(syst.) keV,Γee/Γμμ=1.002±0.021(stat.)±0.013(syst.) can be used to improve the accuracy of the leptonic and full widths and test leptonic universality.Assuming eμ universality and using the world average value of the lepton branching fraction, we also determine the leptonic Γℓℓ=5.59±0.12 keV and total Γ=94.1±2.7 keV widths of the J/ψ meson.
Physics Letters B.
