https://doi.org/10.1140/epjc/s10052-017-5237-3
Regular Article - Theoretical Physics
Feynman–Hellmann theorem for resonances and the quest for QCD exotica
1
Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of Bern, Sidlerstrasse 5, 3012, Bern, Switzerland
2
Helmholtz–Institut für Strahlen–und Kernphysik and Bethe Center for Theoretical Physics, Universität Bonn, 53115, Bonn, Germany
3
Institute for Advanced Simulation (IAS-4), Institut für Kernphysik (IKP-3), Jülich Center for Hadron Physics and JARA-HPC, Forschungszentrum Jülich, 52425, Jülich, Germany
4
Deutsches Elektronen-Synchrotron DESY, 22603, Hamburg, Germany
* e-mail: elvira@itp.unibe.ch
Received:
6
July
2017
Accepted:
16
September
2017
Published online:
4
October
2017
The generalization of the Feynman–Hellmann theorem for resonance states in quantum field theory is derived. On the basis of this theorem, a criterion is proposed to study the possible exotic nature of certain hadronic states emerging in QCD. It is shown that this proposal is supported by explicit calculations in chiral perturbation theory and by large-
arguments. Analyzing recent lattice data on the quark mass dependence in the pseudoscalar, vector meson, baryon octet and baryon decuplet sectors, we conclude that, as expected, these are predominately quark-model states, albeit the corrections are non-negligible.
© The Author(s), 2017
