Inclusive study of bottomonium production in association with an $$\eta $$ η meson in $$e^+e^-$$ e + e - annihilations near $$\varUpsilon (5S)$$ Υ ( 5 S )

We study bottomonium production in association with an $$\eta $$ meson in $$e^+e^-$$ annihilations near the $$\varUpsilon (5S)$$ , at a centre-of-mass energy of $$\sqrt{s}=10.866$$ GeV. The results are based on the 121.4 fb $$^{-1}$$ data sample collected by the Belle experiment at the asymmetric-energy KEKB collider. Only the $$\eta $$ meson is reconstructed and the missing-mass spectrum of $$\eta $$ candidates is investigated. We observe the $$e^+e^-\rightarrow \eta \varUpsilon _J(1D)$$ process and find evidence for the $$e^+e^-\rightarrow \eta \varUpsilon (2S)$$ process, while no significant signals of $$\varUpsilon (1S)$$ , $$h_b(1P)$$ , nor $$h_b(2P)$$ are found. Cross sections for the studied processes are reported.