A new high precision measurement of the J/ψ- and ψ′-meson masses has been performed at the VEPP-4M collider using the KEDR detector. The resonant depolarization method has been employed for the ...absolute calibration of the beam energy. The following mass values have been obtained: MJ/ψ=3096.917±0.010±0.007 MeV,Mψ′=3686.111±0.025±0.009 MeV. The relative measurement accuracy has reached 4×10−6 for J/ψ and 7×10−6 for ψ′, approximately 3 times better than in the previous precise experiments.
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 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.).
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.
Results of the test of the BELLE barrel calorimeter prototype using a tagged photon beam are presented. The prototype consisted of 36 CsI(Tl) counters with the same preamplifiers and shapers as in ...the BELLE calorimeter. The measurements were carried out at the VEPP-4M collider with the tagged photon beam provided by the ROKK-1M facility. The energy resolution for photons was measured in the energy range 40–800
MeV. The achieved energy resolution was 3% for 40
MeV and 1.5% for 800
MeV photons. The results are consistent with the Monte Carlo simulation taking into account effects of the electronics noise.
An experiment, using the new detector Kedr, on the precise measurement of the *t-lepton mass is being readied on the VEPP-4M. The resonance depolarization method is used for absolute calibration of ...the particle energy. The main difficulty in using a polarized beam at the *t-lepton production threshold (1777 MeV) is the closeness of an integral spin resonance (1763 MeV). Experiments observing the polarization of particles in VEPP-4M after injection of the polarized beam from the VEPP-3 storage booster with different detunings from resonance have been performed. For comparison, the depolarization time of a beam due to quantum fluctuations in the presence of characteristic disturbances of the guiding field is calculated. The temporal stability of the energy indications is studied.
The results of the BELLE barrel calorimeter prototype test with the tagged photon beam are presented. The prototype consisted of 36 CsI(Tl) counters with the same readout system as the BELLE ...calorimeter. The measurements were carried out at the VEPP-4 collider with the tagged photon beam provided by the ROKK-1M facility. The energy resolution for photons was measured in the energy range 40–800 MeV. The results are in good agreement with the Monte-Carlo simulation.
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