Relevance of complex  branch points for partial wave analysis

Ceci, S.; Krewald, S.; Hanhart, C.; Svarc, A.; Meißner, U.-G.; Döring, M.

doi:10.1103/PhysRevC.84.015205

Journal Article

PreJuSER-18583

Relevance of complex branch points for partial wave analysis

Ceci, S. ; Döring, M.FZJ* ; Hanhart, C.FZJ* ; Krewald, S. ; Meißner, U.-G.FZJ* ; Svarc, A.

2011
Inst. Woodbury, NY

Physical review / C 84(1), 015205 (2011) [10.1103/PhysRevC.84.015205]

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Please use a persistent id in citations: http://hdl.handle.net/2128/10288 doi:10.1103/PhysRevC.84.015205

Abstract: A central issue in hadron spectroscopy is to deduce-and interpret-resonance parameters, namely, pole positions and residues, from experimental data, for those are the quantities to be compared to lattice QCD or model calculations. However, not every structure in the observables derives from a resonance pole: the origin might as well be branch points, either located on the real axis (when a new channel composed of stable particles opens) or in the complex plane (when at least one of the intermediate particles is unstable). In this paper we demonstrate first the existence of such branch points in the complex plane and then show on the example of the pi N P-11 partial wave that it is not possible to distinguish the structures induced by the latter from a true pole signal based on elastic data alone.

Keyword(s): partial wave analysis ; hadron spectroscopy ; resonance: pole ; S-matrix ; analytic properties ; threshold ; pi nucleon: scattering amplitude ; rho(770): width ; numerical calculations

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Note: This work is supported by the DAAD (Deutscher Akademischer Austauschdienst), Grant No. D/08/00215. It is also supported by the DFG (Deutsche Forschungsgemeinschaft, Gz., Grants No. DO 1302/1-2 and No. SFB/TR-16) and by the EU-Research Infrastructure Integrating Activity "Study of Strongly Interacting Matter" (HadronPhysics2, Grant No. 227431) under the Seventh Framework Program of the EU.; 8 pages, 4 figures; 8 pages, 4 figures

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