There is no κ(900).

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 K*0(1430), while fits to data with Breit–Wigner forms and variable backgrounds can accommodate a κ(900), 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 as model-independent an analytic continuation of the LASS πK scattering results between 825 MeV and 2 GeV as presently possible to determine the number and position of resonance poles. We find that there is a K*0(1430), but no κ(900). The LASS data cannot rule out the possibility of a very low mass κ well below 825 MeV.