On properties of the exotic hadrons from QCD sum rules
1 Institute for High Energy Physics, Austrian Academy of Sciences, Nikolsdorfergasse 18, A-1050 Vienna, Austria
2 D. V. Skobeltsyn Institute of Nuclear Physics, M. V. Lomonosov Moscow State University, 119991, Moscow, Russia
3 Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
Published online: 25 November 2016
We discuss the specific features of extracting properties of the exotic polyquark hadrons (tetraquarks, pentaquarks) compared to the usual hadrons by the QCD sum-rule approach. In the case of the ordinary hadrons, already the one-loop leading-order O(α0s) correlation functions provide the bulk of the hadron observables, e.g., of the form factor; inclusion of radiative corrections O(αs) modifies already nonzero one-loop contributions. In the case of an exotic hadron, the situation is qualitatively different: discussing strong decays of an exotic tetraquark meson, which provide the main contribution to its width, we show that the disconnected leading-order diagrams are not related to the tetraquark properties. For a proper description of the tetraquark decay width, it is mandatory to calculate specific radiative corrections which generate the connected diagrams.
© The Authors, published by EDP Sciences, 2016
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