Spin partners WbJ from the line shapes of the Zb(10610) and Zb(10650)

2019/01/31 by V. Baru, E. Epelbaum, A. A. Filin +3 · 39 citations
Mathematics · Physics and Astronomy · #Algorithm #Combinatorics #Computer science #Geometry #Line (geometry) #Mathematical physics #Mathematics #Nuclear physics research studies #Particle physics #Particle physics theoretical and experimental studies #Physics #Pion #Quantum Chromodynamics and Particle Interactions #Unitarity #hep-ph #nucl-th

paper · pdf · doi:10.1103/physrevd.99.094013

published in Physical review. D/Physical review. D. 99(9) (American Physical Society) · 24 pages, 12 figures

arxiv created 2019/02/04 · openalex created_date 2019/02/21 · openalex publication_date 2019/05/14 · arxiv updated 2019/05/22 · openalex updated_date 2026/08/05

Abstract

In a recent paper [Phys. Rev. D 98, 074023 (2018)], the most up-to-date experimental data for all measured production and decay channels of the bottomoniumlike states Z_b(10610) and Z_b(10650) were analyzed in a field-theoretical coupled-channel approach which respects analyticity and unitarity and incorporates both the pion exchange and a short-ranged potential nonperturbatively. All parameters of the interaction were fixed directly from data, and pole positions for both Z_b states were determined. In this work we employ the same approach to predict in a parameter-free way the pole positions and the line shapes in the elastic and inelastic channels of the (still to be discovered) spin partners of the Z_b states. They are conventionally referred to as W_bJ's with the quantum numbers J^PC=J⁺⁺ (J=0, 1, 2). It is demonstrated that the results of our most advanced pionful fit, which gives the best \ensuremathχ²/d.o.f. for the data in the Z_b channels, are consistent with all W_bJ states being above-threshold resonances which manifest themselves as well-pronounced hump structures in the line shapes. On the contrary, in the pionless approach, all W_bJ's are virtual states which can be seen as enhanced threshold cusps in the inelastic line shapes. Since the two above scenarios provide different imprints on the observables, the role of the one-pion exchange in the B^(*)B^(*) systems can be inferred from the once available experimental data directly.

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