% IMPORTANT: The following is UTF-8 encoded.  This means that in the presence
% of non-ASCII characters, it will not work with BibTeX 0.99 or older.
% Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or
% “biber”.

@ARTICLE{Meissner:889250,
      author       = {Meissner, Ulf-G.},
      title        = {{T}wo-{P}ole {S}tructures in {QCD}: {F}acts, {N}ot
                      {F}antasy!},
      journal      = {Symmetry},
      volume       = {12},
      number       = {6},
      issn         = {2073-8994},
      address      = {Basel},
      publisher    = {MDPI},
      reportid     = {FZJ-2021-00155},
      pages        = {981 -},
      year         = {2020},
      abstract     = {The two-pole structure refers to the fact that particular
                      single states in the spectrum as listed in the PDG tables
                      are often two states. The story began with the Λ(1405) ,
                      when in 2001, using unitarized chiral perturbation theory,
                      it was observed that there are two poles in the complex
                      plane, one close to the K¯¯¯p and the other close to the
                      πΣ threshold. This was later understood combining the
                      SU(3) limit and group-theoretical arguments. Different
                      unitarization approaches that all lead to the two-pole
                      structure have been considered in the mean time, showing
                      some spread in the pole positions. This fact is now part of
                      the PDG book, although it is not yet listed in the summary
                      tables. Here, I discuss the open ends and critically review
                      approaches that cannot deal with this issue. In the meson
                      sector, some excited charm mesons are good candidates for
                      such a two-pole structure. Next, I consider in detail the
                      D∗0(2300) , which is another candidate for this scenario.
                      Combining lattice QCD with chiral unitary approaches in the
                      finite volume, the precise data of the Hadron Spectrum
                      Collaboration for coupled-channel Dπ , Dη , DsK¯¯¯
                      scattering in the isospin I=1/2 channel indeed reveal its
                      two-pole structure. Further states in the heavy meson sector
                      with I=1/2 exhibiting this phenomenon are predicted,
                      especially in the beauty meson sector. I also discuss the
                      relation of these two-pole structures and the possible
                      molecular nature of the states under consideration},
      cin          = {IAS-4 / IKP-3},
      ddc          = {570},
      cid          = {I:(DE-Juel1)IAS-4-20090406 / I:(DE-Juel1)IKP-3-20111104},
      pnm          = {511 - Computational Science and Mathematical Methods
                      (POF3-511) / DFG project 196253076 - TRR 110: Symmetrien und
                      Strukturbildung in der Quantenchromodynamik (196253076)},
      pid          = {G:(DE-HGF)POF3-511 / G:(GEPRIS)196253076},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000550803700001},
      doi          = {10.3390/sym12060981},
      url          = {https://juser.fz-juelich.de/record/889250},
}