Precise measurement of RudsR_{\text{uds}} and RR between 1.84 and 3.72 GeV at the KEDR detector

The present work continues a series of the KEDR measurements of the $R$ value that started in 2010 at the VEPP-4M $e^+e^-$ collider. By combining new data with our previous results in this energy range we measured the values of $R_{\text{uds}}$ and $R$ at nine center-of-mass energies between 3.08 and 3.72 GeV. The total accuracy is about or better than $2.6\%$ at most of energy points with a systematic uncertainty of about $1.9\%$. Together with the previous precise $R$ measurement at KEDR in the energy range 1.84-3.05 GeV, it constitutes the most detailed high-precision $R$ measurement near the charmonium production threshold.Comment: arXiv admin note: text overlap with arXiv:1610.02827 and substantial text overlap with arXiv:1510.0266

Measurement of the branching fraction of J/ψ→ρπJ/\psi\rightarrow\rho\pi at KEDR

We present the study of the decay $J/\psi \rightarrow \rho \pi$. The results are based on of 5.2 million $J/\psi$ events collected by the KEDR detector at VEPP-4M collider. The branching fraction is measured to be $\mathcal{B}(J/\psi\rightarrow\rho\pi) = \big(2.072\pm 0.017 \pm 0.056 \big)\cdot 10^{-2}$ where the first uncertainty is statistical, the second one is systematic. This is the most precise single measurement of this quantity at the moment

Measurement of

Using the 1.32 $$\hbox {pb}^{-1}$$ statistics collected at the $$J/\psi$$ peak with the KEDR detector at the VEPP-4M $$e^{+}e^{-\, }$$collider, we measured the branching fractions of $$J/\psi$$ meson decays to the final states 2($$\pi ^{+}\pi ^{-})\pi ^{0}$$, $$K^{+}K^{-}\pi ^{+}\pi ^{-}\pi ^{0}$$, 2($$\pi ^{+}\pi ^{-})$$ and $$K^{+}K^{-}\pi ^{+}\pi ^{-}$$. The results obtained for the decays $$J/\psi \rightarrow$$2($$\pi ^{+}\pi ^{-})\pi ^{0}$$, $$J/\psi \rightarrow K^{+}K^{-}\pi ^{+}\pi ^{-}\pi ^{0}$$ contradict the measurements performed by other groups in the last century, but agree well with recent results of BABAR and BESIII collaborations