Isf0(975) a narrow resonance?

Abstract

We use a new approach to study the an-, K Z = J = O interaction from information on the central production and elastic processes with energies from the m r threshold to 1.7 GeV. Our amplitude analysis separates the pole term for fo(975) from the background term, meanwhile enforcing unitarity. A second-sheet pole (988-23i MeV) and a third-sheet pole (797-185i MeV) are found for f0(975). We conclude that if the fo(975) is a Breit-Wigner resonance, it has a large decay width corresponding to its third-sheet pole, but shows up as a narrow structure in aa and K K invariant mass spectra due to its second-sheet pole. An alternative K-matrix analysis is also briefly reported, which gives a similar conclusion.

Chiral symmetry amplitudes in the S-wave isoscalar and isovector channels and the σ, f0(980), a0(980) scalar mesons

“…Following this debate, in ref. [7] it is argued that the J/ψ → φππ, φKK decay is crucial in order to distinguish between the two interpretations quoted above, questioning the conclusions of [21] and offering a good description of these data. However, in ref.…”

“…[16] the f 0 , appears as a pole in the II sheet and a description of the J/ψ → φππ, φKK data of the same quality as in [7] is obtained. The main sources of discrepancy between [7] and [21] come from the different ways in which the background is treated.…”

“…[5,6,7] favours this latter interpretation, but in ref. [21] the first interpretation is advocated, since the pole found in the IV sheet is far from threshold. Following this debate, in ref.…”

“…Coming back to the meson-meson interaction in the scalar sector, a large fraction of the work done consists in a parametrization of the amplitudes respecting general principles [4,5,6,7,21] while some other works use models inspired in QCD [11,12,13,14,15] or phenomenological ones based on the exchange of mesons [16].…”

“…The different approaches which are successful in reproducing the meson-meson scattering amplitudes rely upon a relatively high number of parameters which are adjusted to the data, and vary between around 25 in [4,5,6,7,21] and 5-6 in [8,15].…”