SMuK 2023 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 7: Hadron Structure and Spectroscopy I

HK 7.1: Gruppenbericht

Montag, 20. März 2023, 16:30–17:00, SCH/A316

A coupled channel analysis of e⁺e⁻ annihilation in the bottomonium region — •Nils Hüsken^1,2, Ryan Mitchell², and Eric Swanson³ — ¹Johannes Gutenberg-Universität Mainz — ²Indiana University Bloomington — ³University of Pittsburgh

In recent years, a large number of exotic hadron candidates have been discovered in the charmonium and bottomonium regions. Electron positron annihilation in experiments like BaBar, BESIII, Belle(II) and CLEO has played an important role in the discoveries of many of these charmonium- and bottomonium-like states, in particular of vector-states directly produced in the collision. Thus far, new resonances have regularly been studied using fits of simplified models to the cross sections of e⁺e⁻ annihilation to exclusive final states, leading to large model dependencies. Here, we will present the first global and unitary analysis of e⁺e⁻→ bb cross sections including exclusive cross sections in the BB, B^*B(+c.c.), B^*B^*, B_s^*B_s^*, Υ(nS)π⁺π⁻ and h_b(nP)π⁺π⁻ channels as well as the total inclusive cross section for bb production. Pole positions and residues are determined for four vector-bottomonium states, which we associate with the Υ(4S), Υ(10750), Υ(10860) and Υ(11020). Strong evidence is found for the new Υ(10750) recently claimed by Belle, although with parameters not well constrained by the data. Results presented here cast doubt on the validity of branching ratios reported earlier using Breit-Wigner parametrizations or ratios of cross sections. * This work received funding from the European Union Horizon 2020 research and innovation program under Marie Skłodowska-Curie Grant Agreement No. 894790