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The kappa in E791 data for D->K-pi-pi
A combined fit is made to E791 data on D->K-pi-pi, LASS data on K-pi elastic
scattering, and BES II data on J/Psi->K*(890)-K-pi.In all cases, the K-pi
S-wave is fitted well with a kappa resonance and Ko(1430); the kappa requires
an s-dependent width with an Adler zero near threshold. The pole position of
the kappa is at M - iGamma/2 = (750 +30 -55) - i(342 +- 60) MeV. The E791
collaboration fitted their data using a form factor for the production process
D->kappa-pi. It is shown that this form factor is not needed. The data require
point-like production with an RMS radius <0.38 fm with 95 percent confidence.Comment: 11 pages, 4 figures. Typos corrected. Material added to explain how a
pole is possible without the phase shift on the real s-axis going through 90
degree
Experimental disagreements with Extended Unitarity
In production processes, e.g. J/Psi -> omega-pi-pi or pbar-p -> 3pi, the
sigma and fo(980) overlap in the same partial wave. The conjecture of Extended
Unitarity (EU) states that the pi-pi pair should have the same phase variation
as pi-pi elastic scattering. This is an extension of Watson's theorem beyond
its original derivation, which stated only that the s-dependence of a single
resonance should be universal. The prediction of EU is that the deep dip
observed in pi-pi elastic scattering close to 1 GeV should also appear in
production data. Four sets of data disagree with this prediction. All require
different relative magnitudes of sigma and fo(980). That being so, a fresh
conjecture is to rewrite the 2-body unitarity relation for production in terms
of observed magnitudes. This leads to a prediction different to EU. Central
production data from the AFS experiment fit naturally to this hypothesis.Comment: 24 pages, 12 figures. To be published in Euro. Phys. J
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