We report measurements of the $e^+e^- \to B\bar{ B}$, $B\bar{ B}{ }^*$, and $B^*\bar{ B}{ }^*$ cross sections at four energies, 10653, 10701, 10746 and 10805 MeV, using data collected by the Belle~II experiment. We reconstruct one $B$ meson in a large number of hadronic final states and use its momentum to identify the production process. In the first $2-5$ MeV above $B^*\bar{ B}{ }^*$ threshold, the $e^+e^- \to B^*\bar{ B}{ }^*$ cross section increases rapidly. This may indicate the presence of a pole close to the threshold.
Categories: hep-ex