The Belle and Belle II experiments have collected an 1.6 ab$^{ -1}$ sample of $e^+e^-$ collision data at center-of-mass energies near the $\Upsilon(nS)$ resonances. In particular, the Belle II experiment collected a 19.2 fb$^{ -1}$ sample of data at center-of-mass energies near the $\Upsilon(10753)$ resonance. We study the following processes: $e^+e^-\to \Upsilon(nS)\eta$, $e^+e^-\to \gamma X_b(\chi_{ bJ}\pi^+\pi^-)$, and $e^{ +}e^{ -}\to\chi_{ bJ}(1P) \gamma$. These results provide additional information about the nature of the $\Upsilon(10753)$ resonance and nearby structures. In addition, we measure the $B^{ 0}$ and $B^+$ meson mass difference, and $\sigma\left(e^+ e^-\to J/\psi p\bar{ p}\right)$ over a range of center-of-mass energies accessed via initial-state radiation.
Categories: hep-ex