Historical Introduction to Chiral Quark Models

Chiral symmetry, and its dynamical breaking, has become a cornerstone in the description of the hadron’s phenomenology at low energy. The present manuscript gives a historical survey on how the quark model of hadrons has been implemented along the last decades trying to incorporate, among other important non-perturbative features of quantum chromodynamics (QCD), the dynamical chiral symmetry breaking mechanism. This effort has delivered different models such as the chiral bag model, the cloudy bag model, the chiral quark model or the chiral constituent quark model. Our main aim herein is to provide a brief introduction of the Special Issue “Advances in Chiral Quark Models” in Symmetry and contribute to the clarification of the differences among the above-mentioned models that include the adjective chiral in their nomenclature.

Exclusive open-charm near-threshold cross sections in a coupled-channel approach

Data on 7 open-charm channels collected by the Belle Collaboration are analyzed simultaneously using a unitary approach based on a coupled channel model in a wide energy range $ \sqrt s $ = 3.7 − 4.7 GeV. The resulting fit provides a remarkably good overall description of the line shapes in all studied channels. Parameters of 5 vector charmonium resonances are extracted from the fit. It is demonstrated, that this approach could be used account for all exclusive channels and thus solve the long-term problem of the charmonium spectra near threshold.