The branching fraction measurements of $J/ψ$ decay into $ρη$ and $φη$ final states
KEDR Collaboration, V. V. Anashin, O. V. Anchugov, K. V. Astrelina, V. M. Aulchenko, V. V. Balakin, E. M. Baldin, G. N. Baranov, A. K. Barladyan, A. Yu. Barnyakov, M. Yu. Barnyakov, I. Yu. Basok, E. A. Bekhtenev, O. V. Belikov, D. E. Berkaev, A. E. Blinov, V. E. Blinov, A. V. Bobrov, V. S. Bobrovnikov, A. V. Bogomyagkov, D. Yu. Bolkhovityanov, A. E. Bondar, V. M. Borin, A. R. Buzykaev, V. L. Dorokhov, D. V. Dorokhova, F. A. Emanov, D. N. Grigoriev, V. V. Kaminskiy, S. E. Karnaev, G. V. Karpov, K. Yu. Karukina, P. V. Kasyanenko, A. A. Katcin, T. A. Kharlamova, V. A. Kiselev, A. A. Kovalenko, E. V. Kozyrev, A. A. Krasnov, E. A. Kravchenko, V. N. Kudryavtsev, V. F. Kulikov, G. Ya. Kurkin, I. A. Kuyanov, D. A. Kyshtymov, N. N. Lebedev, E. B. Levichev, P. V. Logachev, D. A. Maksimov, T. V. Maltsev, V. M. Malyshev, R. Z. Mamutov, A. L. Maslennikov, O. I. Meshkov, I. I. Morozov, I. A. Morozov, A. A. Murasev, S. A. Nikitin, I. B. Nikolaev, I. N. Okunev, S. B. Oreshkin, A. A. Osipov, I. V. Ovtin, A. V. Pavlenko, S. V. Peleganchuk, K. G. Petrukhin, P. A. Piminov, S. G. Pivovarov, A. V. Polyanskiy, V. G. Prisekin, O. L. Rezanova, A. A. Ruban, G. A. Savinov, D. V. Senkov, A. G. Shamov, L. I. Shekhtman, D. A. Shvedov, B. A. Shwartz, E. A. Simonov, S. V. Sinyatkin, M. A. Skamarokha, A. N. Skrinsky, A. V. Sokolov, E. V. Starostina, D. P. Sukhanov, A. M. Sukharev, A. A. Talyshev, V. A. Tayursky, V. I. Telnov, Yu. A. Tikhonov, K. Yu. Todyshev, Yu. V. Usov, A. I. Vorobiov, V. N. Zhilich, A. A. Zhukov, V. V. Zhulanov, A. N. Zhuravlev, D. A. Zubkov
Published: 2025/6/10
Abstract
We present measurements of the branching fractions for the $J/\psi$ meson decays into the $\rho\eta$ and $\phi\eta$ final states, based on data collected with the KEDR detector at the VEPP-4M collider. The data set consisted of 4.93 million $J/\psi$ events. The resulting branching fractions are: - $\mathcal{B}(J/\psi \to \rho\eta) = (2.04 \pm 0.58 \pm 0.39)\times 10^{-4}$, - $\mathcal{B}(J/\psi \to \phi\eta) = (7.82 \pm 1.17 \pm 0.58) \times 10^{-4}$, where the first uncertainty is statistical and the second one is systematic. In the study of the $\rho\eta$ decay, the dynamics of $J/\psi\to\pi^+\pi^-\eta$ is analyzed. The hints from contributions of $\rho(1450)\eta$ and $a^{\pm}_2\pi^{\mp}$ intermediate states are observed. Additional measured branching fractions in the model that includes $\rho(1450)\eta$ and $a^{\pm}_2\pi^{\mp}$ are: - $\mathcal{B}(J/\psi \to \pi^+\pi^-\eta) = (4.73 \pm 0.49 \pm 1.17)\times10^{-4}$, - $\mathcal{B}(J/\psi \to (a_2^+\pi^- + a_2^- \pi^+)) = (1.05\pm 0.37 \pm 0.34)\times 10^{-3}$, - $\mathcal{B}(J/\psi \to \rho(1450)\eta \to \pi^+\pi^-\eta) < 1.51 \times 10^{-4}$, at a confidence level of 90\%. All results are consistent with previous studies.