K-matrix Analysis of e⁺e^-Annihilation in the Bottomonium Region

In recent years, a number of exotic hadron candidates have been observed in e⁺e^- annihilation in both the charmonium- and bottomonium-regions. Most commonly, the existence of these new, potentially exotic states is inferred from cross sections parameterized with sums of Breit-Wigner amplitudes. While this is a reasonable approximation in the case of narrow, well seperated resonances away from important thresholds, the complicated cross sections in the charmonium- and bottomonium regions cast doubt on the validity of these models. We therefore perform the first unitary analysis of bottomonium production data using both exclusive cross sections of open- and hidden-bottom meson production and the total cross section for bottom anti-bottom quark pair-production measured by the Belle and BABAR experiments. In the talk, our approach as well as first results including pole positions and partial widths of the vector-bottomonium(-like) states above 10.5 GeV will be presented and discussed.