The spectrum of scalar-meson nonets in the Resonance-Spectrum Expansion

Abstract

We argue that the low-lying scalar-meson nonet makes part of a subset of a family of infinitely many scalar-meson nonets, which in turn makes part of a family of infinitely many quark-antiquark bound states and resonances. We outline the properties of this subset.Comment: Talk presented at the workshop on "Scalar Mesons and Related Topics" honoring the 70th birthday of Michael Scadron, 11 pages, 7 figure

S-wave andP-wave ππ andKπ contributions to three-body decay processes in the Resonance- Spectrum Expansion

“…Moreover, one cannot just remove a pole from this amplitude, in order to verify whether or not it contributes significantly to the experimental signal. Whereas, in most cases, one can relate resonant structures in elastic scattering to each of the poles in the scattering amplitude, here such a relation is not evident at all, since most of the poles [38] in the ππ and Kπ S-wave amplitudes do not show up as peaked structures in Fig. 4 for the total RSE amplitude (9).…”

“…For the choice (1) of confinement force, we determine E 0ℓqq = m q + mq + (1.5 + ℓ qq )ω. Once the effective flavour masses and ω are fixed [20], we may describe other systems, like scalar mesons and mixed flavours [21][22][23][24][25].…”

“…But it has yet another advantage. The elastic two-meson (MM) scattering amplitude, which can be written in the form [2,5] …”

Y(3940),Z(3930), and theXMolina1, Oset2 2009Phys. Rev. D

“…Also in [28] the authors find that the P-charmonium χ ′′ cJ (J = 0, 1) associated to the Y (4140) is problematic because of the upper limit of the branching ratio of the decay Y (4140) → J/ψφ computed of the order of 10 −4 − 10 −3 . In [29] a tetraquark structure is suggested for this state, while in [30] it is argued than the peak at this energy is just a φJ/ψ threshold effect.…”

Molecular interpretation of the XYZ states

“…The coupling constants are calculated by means of the compositeness condition of Weinberg. In [13] it is argued that the peak at 4140 MeV named as the Y(4140) is just a φJ/ψ threshold effect. In [14], the hidden gauge formalism is applied to study the vector -vector interaction in the charm sector and the authors obtain dynamically generated states from this interaction which are close to the D * D * and D * sD * s thresholds.…”