paper

There is no

arXiv:hep-ph/0005208 · doi:10.1016/S0375-9474(00)00587-X

Abstract

In the I=0 sector there are more scalar mesons than can fit in one nonet. Consequently, many have claimed that there is in fact more than one multiplet, perhaps both and . Such proposals require the existence of at least two strange isodoublets (and their antiparticles). The current PDG Tables list just one state, the , while fits to data with Breit-Wigner forms and variable backgrounds can accommodate a too. Whether a state exists in the spectrum of hadrons is not a matter of ability to fit data along the real energy axis, but is completely specified by the number of poles in the complex energy plane. Here we perform a model-independent analytic continuation of scattering results between 825 MeV and 2 GeV to determine the number and position of resonance poles. We find that there {\bf is} a , but {\bf no} . The LASS data cannot rule out the possibility of a very low mass well below 825 MeV.

19 pages, 5 figures Version to be published in Nuclear Physics A containing new figures and additional entries in tables to clarify the role played by near threshold scattering$ below the energy explored by the SLAC LASS experiment

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