Constituent and current quark masses at low chiral energies

Light constituent quark masses and the corresponding dynamical quark masses are determined by data, the Quark-Level Linear $\sigma$ Model, and infrared QCD. This allows to define effective nonstrange and strange current quark masses which reproduce the experimental pion and kaon masses very accurately, by simple additivity. Moreover, the masses of the light scalar mesons $\sigma(600)$ and $\kappa(800)$ can be obtained straightforwardly from the constituent quark masses. In contrast, the usual nonstrange and strange current quark masses employed by Chiral Perturbation Theory do not allow a simple quantitative explanation of the pion and kaon masses.Comment: 5 pages, EPL style, accepted for publication in Europhys. Let

Why the f(0)(980) is mostly ssbar

We exploit the W-emission process to study the measured weak decay of the D(s,+)(1.9686) meson into f(0)(980) and a positively charged pion. We conclude that the scalar f(0)(980) meson contains mostly strange-antistrange flavors, which is supported by different model studies.Comment: 5 pages, plain LaTeX, minor changes, acknowledgment

Mach 5 inlet CFD and experimental results

An experimental research program was conducted in the NASA Lewis Research Center 10 x 10 ft supersonic wind tunnel. The 2-D inlet model was designed to study the Mach 3.0 to 5.0 speed range for an over-under turbojet plus ramjet propulsion system. The model was extensively instrumented to provide both analytical code validation data as well as inlet performance information. Support studies for the program include flow field predictions with both 3-D parabolized Navier-Stokes (PNS) and 3-D full Navier-Stokes (FNS) analytical codes. Analytical predictions and experimental results are compared

Comment on "Two-photon decay of the sigma meson"

We comment on a recent paper by Giacosa, Gutsche, and Lyobovitskij, in which it is argued that a quarkonium interpretation of the $\sigma$ meson should give rise to a much smaller two-photon decay width than commonly assumed. The reason for this claimed discrepancy is a term in the transition amplitude, necessary for gauge invariance, which allegedly is often omitted in the literature, including the work of the present authors. Here we show their claims to be incorrect by demonstrating, in the context of the Quark-Level Linear $\sigma$ Model, that the recently extracted experimental value $\Gamma_{\sigma\to2\gamma}=(4.1\pm0.3)$ keV is compatible with a $q\bar{q}$ assignment for the $\sigma$, provided that meson loops are taken into account as well.Comment: RevTeX, 4 pages, Comment on Phys. Rev. D 77 (2008) 034007 [0710.3403 [hep-ph]

Pion and Kaon Masses and Pion Form Factors from Dynamical Chiral-Symmetry Breaking with Light Constituent Quarks

Light constituent quark masses and the corresponding dynamical quark masses are determined by data, the quark-level linear sigma model, and infrared QCD. This allows to define effective nonstrange and strange current quark masses, which reproduce the experimental pion and kaon masses very accurately, by simple additivity. In contrast, the usual nonstrange and strange current quarks employed by the Particle Data Group and Chiral Perturbation Theory do not allow a straightforward quantitative explanation of the pion and kaon masses.Comment: 4 pages, AIP style, contribution to conference ``Quark Confinement and the Hadron Spectrum VII'', Azores, Portugal, 2-7 September 200

Remarks on the f_0(400-1200) scalar meson as the dynamically generated chiral partner of the pion

The quark-level linear sigma model is revisited, in particular concerning the identification of the f_0(400-1200) (or \sigma(600)) scalar meson as the chiral partner of the pion. We demonstrate the predictive power of the linear sigma model through the pi-pi and pi-N s-wave scattering lengths, as well as several electromagnetic, weak, and strong decays of pseudoscalar and vector mesons. The ease with which the data for these observables are reproduced in the linear sigma model lends credit to the necessity to include the sigma as a fundamental q\bar{q} degree of freedom, to be contrasted with approaches like chiral perturbation theory or the confining NJL model of Shakin and Wang.Comment: 15 pages, plain LaTeX, 3 EPS figure