20.500.12556/DKUM-66977 Measurement of branching fractions for $B \to J/\psi \eta K$ decays and search for a narrow resonance in the $J/\psi \eta$ final state We report an observation of the $B^{\pm } \to J/\psi \eta K^{\pm }$ and $B^0 \to J/\psi \eta K^0_S$ decays using $772\times 10^{6}B\overline {B}$ pairs collected at the $\Upsilon (4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. We obtain the branching fractions ${\mathcal B}(B^{\pm }\rightarrow J/\psi \eta K^{\pm })=(1.27\pm 0.11(\hbox {stat.})\pm 0.11(\hbox {syst.}))\times 10^{-4}$ and ${\mathcal B}(B^0\to J/\psi \eta K^0_S)=(5.22 \pm 0.78 (\hbox {stat.}) \pm 0.49 (\hbox {syst.}))\times 10^{-5}$. We search for a new narrow charmonium(-like) state $X$ in the $ J/\psi \eta$ mass spectrum and find no significant excess. We set upper limits on the product of branching fractions, ${\mathcal B}(B^\pm \to XK^\pm){\mathcal B}(X \to J/\psi \eta)$, at $3872\,\hbox {MeV}\,c^{-2}$ where a $C$-odd partner of $X(3872)$ may exist, at $\psi (4040)$ and $\psi (4160)$ assuming their known mass and width, and over a range from 3.8 to $4.8\,\hbox {GeV}\,c^{-2}$. The obtained upper limits at 90% confidence level for $X^{C\hbox {-}{\rm odd}}(3872)$, $\psi (4040)$, and $\psi (4160)$ are $3.8\times 10^{-6}$, $15.5\times 10^{-6}$, and $7.4\times 10^{-6}$, respectively. C07 C21 particle properties lepton collider experiments experimental particle physics C07 C21 lastnosti delcev eksperimenti leptonski trkalnik eksperimentalna fizika delcev true false true Angleški jezik Slovenski jezik Znanstveno delo 2017-07-21 12:45:37 2017-07-21 12:48:57 2022-08-01 13:24:34 2019-07-11 16:05:18 2014 0 0 str. 1-11 št. 4 Letn. 2014 2014 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 2050-3911 539.1 2704635 28162343 10.1093/ptep/ptu043 2050-3911 URN:SI:UM:DK:GX0ZKAEF Progress_of_Theoretical_and_Experimental_Physics_2014_Iwashita_et_al._Measurement_of_branching_fractions_for_B→_JψηK_decays_and_search_f.pdf Progress_of_Theoretical_and_Experimental_Physics_2014_Iwashita_et_al._Measurement_of_branching_fractions_for_B→_JψηK_decays_and_search_f.pdf 1 48C1B8D0B78234936C4EF7B4CFC4309D cb881494f22d7bbc2c307df3cd3921dc25ea738c64cfcf231d3f05d6c9782ce0 7090a0e0-7c0e-11eb-bb7a-00155d0001ca 20.500.12556/dkum/ddc5ba05-6879-499d-afca-d14e244eba0f https://dk.um.si/Dokument.php?lang=slv&id=114445 https://academic.oup.com/ptep/article-lookup/doi/10.1093/ptep/ptu043 1 https://dk.um.si/Dokument.php?lang=slv&id=114444 Fakulteta za kemijo in kemijsko tehnologijo 0 0 0