Measurements of the mass difference $m(B^0)-m(B^{+})$ and the energy dependence of the cross-section ratio $\sigma (e^{+}{e}^{-}\to B^0{\bar{B}}^0)/\sigma (e^{+}{e}^{-}\to B^{+}{B}^{-})$ at Belle and Belle II

Belle, Belle II Collaborations, : +396

Using data samples collected by the Belle and Belle II experiments at the ${\rm Y}(4S)$ resonance with integrated luminosities of 571 fb${}^{-1}$ and 365 fb${}^{-1}$, respectively, we measur…