Scalar and axial-vector mesons

Abstract

Nowadays, there exists an abundance of theoretical approaches towards the mesonic spectrum, ranging from confinement models of all kinds, i.e., glueballs, and quark-antiquark, multiquark and hybrid configurations, to models in which only mesonic degrees of freedom are taken into account. Nature seems to come out somewhere in the middle, neither preferring pure bound states, nor effective meson-meson physics with only coupling constants and possibly form factors. As a matter of fact, apart from a few exceptions, like pions and kaons, Nature does not allow us to study mesonic bound states of any kind, which is equivalent to saying that such states do not really exist. Hence, instead of extrapolating from pions and kaons to the remainder of the meson family, it is more democratic to consider pions and kaons mesonic resonances that happen to come out below the lowest threshold for strong decay. Nevertheless, confinement is an important ingredient for understanding the many regularities observed in mesonic spectra. Therefore, excluding quark degrees of freedom is also not the most obvious way of describing mesons in general, and scalars and axial-vectors in particular.

13 pages, 3 Postscript figures; plenary talk at the IVth International Conference on Quarks and Nuclear Physics (QNP06), Madrid, 5-10 June 2006; v2: correction w.r.t. the work of Ref. 87; v3: Ref. 87 corrected; v4: small corrections

References in corpus (6)

• A low-lying scalar meson nonet in a unitarized meson model
• Analysis of U${}_A$(1) symmetry-breaking and restoration effects on the scalar-pseudoscalar spectrum
• Multichannel calculation of the very narrow $D_{s0}^{\ast }(2317)$ and the very broad $D_0^{\ast }(2300-2400)$
• D_{s0}^+(2317) as an iso-triplet four-quark meson
• BABAR Resonance and Four-quark Mesons
• Study of the semileptonic decays B->pi, D->pi and D->K

Cited by in corpus (4)

• S-wave and P-wave pion-pion and kaon-pion contributions to three-body decay processes in the Resonance-Spectrum Expansion
• How we discovered the nonet of light scalar mesons
• Pion-pion scattering near threshold in the Resonance-Spectrum Expansion
• New c-cbar structure around 3764 MeV at BES and predictions from unquenching the confinement spectrum