اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدMeasurement of $Gamma_{ee}(J/psi)$ with KEDR detector
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The product of the electronic width of the $J/psi$ 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: $Gamma_{ee}(J/psi) = 5.550 pm 0.056 pm 0.089 , text{keV}, $ $Gamma_{ee}(J/psi) cdot mathcal{B}_text{hadrons}(J/psi) = 4.884 pm 0.048 pm 0.078 , text{keV}, $ $Gamma_{ee}(J/psi) cdot mathcal{B}_{ee}(J/psi) = 0.3331 pm 0.0066 pm 0.0040 , text{keV}.$ 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 $J/psi$ meson: $Gamma = 92.94 pm 1.83 , text{keV}.$ These results are consistent with the previous experiments.
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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/p
si->e^+e^-)=(0.3323pm0.0064pm0.0048) keV, Gamma_{ee}(J/psi)*Br(J/psi->mu^+mu^-)=(0.3318pm0.0052pm0.0063) keV. Their combinations Gamma_{ee}times(Gamma_{ee}+Gamma_{mumu})/Gamma=(0.6641pm0.0082pm0.0100) keV, Gamma_{ee}/Gamma_{mumu}=1.002pm0.021pm0.013 can be used to improve theaccuracy of the leptonic and full widths and test leptonic universality. Assuming emu universality and using the world average value of the lepton branching fraction, we also determine the leptonic Gamma_{ll}=5.59pm0.12 keV and total Gamma=94.1pm2.7 keV widths of the J/psi meson.
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The ratio of the electron and muon widths of the $J/psi$ meson has been measured using direct $J/psi$ decays in the KEDR experiment at the VEPP-4M electron-positron collider. The result $Gamma_{ee}(J/psi)/Gamma_{mumu}(J/psi)=1.0022pm0.0044pm0.0048 (0
.65%)$ is in good agreement with the lepton universality. The experience collected during this analysis will be used for a $J/psi$ lepton width determination with up to 1% accuracy.
The product of the electronic width of the $psi(2S)$ meson and the branching fraction of its decay to the muon pair was measured in the $e^{+}e^{-} to psi(2S) to mu^{+}mu^{-}$ process using nine data sets corresponding to an integrated luminosity of
about 6.5 pb$^{-1}$ collected with the KEDR detector at the VEPP-4M electron-positron collider: [ Gamma_{ee}timesmathcal{B}_{mumu} = 19.3 pm 0.3 pm 0.5 ~text{eV}. ] Adding the previous KEDR results on hadronic and leptonic channels, the values of the $psi(2S)$ electronic width were obtained under two assumptions: either with the assumption of lepton universality [ Gamma_{ee} = 2.279 pm 0.015 pm 0.042 ~text{keV} ] or without it, summing up hadronic and three independent leptonic channels: [ Gamma_{ee} = 2.282 pm 0.015 pm 0.042 ~text{keV}. ]
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