Phenomenology of near-threshold states: a practical parametrisation for the line shapes
1 State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, China
2 Helmholtz-Institut für Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Universität Bonn, D-53115 Bonn, Germany
3 Forschungszentrum Jülich, Institute for Advanced Simulation, Institut für Kernphysik (Theorie) and Jülich Center for Hadron Physics, D-52425 Jülich, Germany
4 Institute for Theoretical and Experimental Physics, 117218, B.Cheremushkinskaya 25, Moscow, Russia
5 National Research Nuclear University MEPhI, 115409, Kashirskoe highway 31, Moscow, Russia
6 Lebedev Physics Institute, 119991, Leninsky prospect 53, Moscow, Russia
7 Moscow Institute of Physics and Technology, 141700, 9 Institutsky lane, Dolgoprudny, Moscow Region, Russia
a e-mail: email@example.com
Published online: 22 March 2017
In the last decade many states in the spectrum of charmonium and bottomonium have been observed experimentally above the lowest open-flavour threshold. Most of these states reside in the vicinity of strong thresholds and show properties that cannot be captured by simple quark models. Description and understanding of such exotic states is a challenge for the phenomenology of strong interactions, since it requires building adequate theoretical tools and approaches. In this work, a practical parametrisation for the line shapes of near threshold resonance(s) is derived in the framework of a coupled-channel model which includes an arbitrary number of elastic and inelastic channels as well as of bare pole terms. Parameters of the distribution have a direct relation to phenomenology and the resulting analytical parametrisation is therefore ideally suited to harvest the full information content provided by the measurements and to establish a link between the experimental data and their theoretical interpretation.
© The Authors, published by EDP Sciences, 2017
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