Studies of Hadron Spectroscopy at Belle and Belle II

Abstract: 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 $Υ(nS)$ resonances. In particular, the Belle II experiment collected a 19.2 fb$^{-1}$ sample of data at center-of-mass energies near the $Υ(10753)$ resonance. We study the following processes: $e^+e^-\to Υ(nS)η$, $e^+e^-\to γX_b(χ{bJ}π^+π^-)$, and $e^{+}e^{-}\toχ{bJ}(1P) γ$. These results provide additional information about the nature of the $Υ(10753)$ resonance and nearby structures. In addition, we measure the $B^{0}$ and $B^+$ meson mass difference, and $σ\left(e^+ e^-\to J/ψp\bar{p}\right)$ over a range of center-of-mass energies accessed via initial-state radiation.