The ratio of the electron and muon widths of the J/ psi J/ psi meson has been measured using direct J/ psi J/ psi decays in the KEDR experiment at the VEPP-4M electron-positron collider. The result ...Gamma e+e-(J/ psi )/ Gamma mu + mu -(J/ psi )=1.0022 plus or minus 0.0044 plus or minus 0.0048(0.65%) is in good agreement with the lepton universality. The experience collected during this analysis will be used for J/ psi J/ psi lepton width determination with up to 1% accuracy.
Measurement of parameters Anashin, V V; Aulchenko, V M; Baldin, E M ...
Physics letters. B,
05/2012, Letnik:
711, Številka:
3-4
Journal Article
Recenzirano
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 ...interference between the resonant and nonresonant D D macr 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 N R ( s ) . Our results for the mass and total width of psi ( 3770 ) are M = 3779.2 - 1.7 + 1.8 - 0.7 + 0.5 - 0.3 + 0.3 MeV , Gamma = 24.9 - 4.0 + 4.6 - 0.6 + 0.5 - 0.9 + 0.2 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 e e = 154 - 58 + 79 - 9 + 17 - 25 + 13 eV , ( 2 ) Gamma e e = 414 - 80 + 72 - 26 + 24 - 10 + 90 eV . Our statistics are insufficient to prefer one solution to another. The Solution (2) mitigates the problem of non- D D macr 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 cannot be directly compared with the corresponding PDG values obtained ignoring this effect.
A high-precision determination of the main parameters of the psi ( 2 S ) resonance has been performed with the KEDR detector at the VEPP-4M e + e - collider in three scans of the psi ( 2 S ) - psi ( ...3770 ) energy range. Fitting the energy dependence of the multihadron cross section in the vicinity of the psi ( 2 S ) we obtained the mass value M = 3686.114 plus or minus 0.007 plus or minus 0.011 - 0.012 + 0.002 MeV and the product of the electron partial width by the branching fraction into hadrons Gamma e e B h = 2.233 plus or minus 0.015 plus or minus 0.037 plus or minus 0.020 keV . The first and second uncertainties are statistical and systematic, respectively. The third uncertainty 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 ( 2 S ) : Gamma e e = 2.282 plus or minus 0.015 plus or minus 0.038 plus or minus 0.021 keV , Gamma = 296 plus or minus 2 plus or minus 8 plus or minus 3 keV . These results are consistent with and more than two times more precise than any of the previous experiments.
We propose an experiment to search for a new gauge boson A' in e+e− annihilation by means of a positron beam incident on a gas hydrogen target internal to the bypass at the VEPP-3 storage ring. The ...search method is based on a missing mass spectrum in the reaction e+e−→γA'. It allows observation of the A' signal independently of its decay modes and life time. The projected result of this experiment corresponds to an upper limit on the square of the coupling constant ϵ2=3ċ10−8 with a signal-to-noise ratio of two to one at an A' mass of 5–20 MeV .
Internal polarized deuterium target with cryogenic atomic beam source Dyug, M.V; Isaeva, L.G; Lazarenko, B.A ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2002, Letnik:
495, Številka:
1
Journal Article
Recenzirano
Description of the polarized deuterium gas target used at the VEPP-3 electron storage ring for experiments on elastic and inelastic
ed scattering is given. Superconducting sextupole magnets with the ...pole tip magnetic field up to
4.8
T
are used in atomic beam source (ABS) to focus atoms. The flux of polarized atoms injected into the storage cell was measured to be
8.2×10
16
at/
s
for deuterium and
7.9×10
16
at/
s
for hydrogen. The measured target thickness
8×10
13
at/
cm
2
is consistent with the thickness calculated from the measured beam intensity. The effective tensor polarization of the deuterium target during the experiment was found to be P
zz
=0.397. Further improvements of the target and possible limitation of the beam intensity from ABS are discussed.
We report results of a search for narrow resonances in e super(+e) super(-) annihilation at center-of-mass energies between 1.85 and 3.1 GeV performed with the KEDR detector at the VEPP-4M e ...super(+e) super(-) collider. The upper limit on the leptonic width of a narrow resonance inline image has been obtained (at 90% C.L.).
Deuterium target polarimeter at the VEPP-3 storage ring Dyug, M.V.; Lazarenko, B.A.; Mishnev, S.I. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2005, Letnik:
536, Številka:
3
Journal Article
Recenzirano
The polarimeter for the internal tensor polarized deuterium gas target is described. Polarimeter is based on a target asymmetry measurement of elastic
ed-scattering at a small momentum transfer. It ...was used in elastic and inelastic scattering experiments at VEPP-3 electron storage ring.
Absolute calibration of particle energy at VEPP-4M Blinov, V.E; Bogomyagkov, A.V; Karnaev, S.E ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2002, Letnik:
494, Številka:
1
Journal Article
Recenzirano
We have started a new series of experiments on a precise measurement of
J/
Ψ-,
Ψ′- mesons and
τ-lepton masses at VEPP-4M collider with KEDR detector. Features of the method used for an absolute ...particle energy calibration based on the resonance depolarization are described.
A new method to determine the polarization of an electron beam circulating in a storage ring by a non-destructive way, based on measuring the asymmetry in scattering of beam electrons on electrons of ...the internal polarized gas jet target, has been developed and tested at the VEPP-3 storage ring.
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