Translating Quark Dynamics Into Hadron Physics (And Back Again)

Abstract

Why should we study mesons in 2002? Two approaches to relating quark and gluon dynamics to hadron physics, namely QCD sum rules and effective field theories, are briefly discussed. These are linked by progress in the study of strong QCD, both by lattice Monte Carlo methods and in the continuum. These provide the translation from quark dynamics to hadron physics and back again. Scope for more theoretical work and further experiments to elucidate the nature of the QCD vacuum and its precise relation to scalar mesons and their interactions is outlined. 13.65.+i, 14.40.Gx

Magnetic test of chiral dynamics in QCD

“…Recently in [49] these results were extended to account for growing current quark masses m q , and in particular the dependence of qq on m q was established to be in agreement with lattice data [50][51][52][53][54].…”

“Could charm (& τ) transitions be the ‘poor princess’ providing a deeper understanding of fundamental dynamics ?” or: “Finding novel forces”

“…One obtains differences of ∼ 0.2 GeV in both cases; therefore, this approach is satisfactory, but this is not an accurate tool. We have a better understanding of this: the mixing of 0|ūu|0 , 0|dd|0 between 0|ss|0 with scalar resonances are not OZI suppressed [43][44][45]. It makes sense to use U-spin symmetry when considering the spectroscopy of charm & beauty hadrons.…”

“…The usual Breit-Wigner parametrization does not describe the impact of broad resonances such as σ/f 0 (500) & κ/K * 0 (800) [60][61][62][63][43][44][45] on both charm (& beauty) hadronic FS well, for various reasons. The interference of narrow and broad resonances cannot be described as being simply "inside" and "outside" the centers of the narrow resonances.…”

“…FSI by strong forces cannot be calculated from first principles at present. Yet, one can relate these factors using nontrivial theoretical tools incorporating chiral symmetry and refined dispersion relations [60][61][62][63][43][44][45], which are based on data concerning low-energy pion and kaon collisions. The crucial strength in this approach is that we cannot depend on the best fitted data, but rather on correlations with other transitions based on tested theories.…”

“…We require further thought, redefined tools and, in particular, consideration of correlations with other FS based on CPT invariance. In the future, dispersion relations [43][44][45][60][61][62][63] based on lowenergy collisions of two hadrons will be used; their power lies in combining data with experimental & theoretical tools.…”