Related papers: Virtual quarks, vacuum stability and scalar meson …
We perform a complete one-loop calculation of meson-meson scattering, and of the scalar and pseudoscalar form factors in U(3) chiral perturbation theory with the inclusion of explicit resonance fields. This effective field theory takes into…
In the first part of the talk, I review what we know (or rather do not know) about the structure of the QCD vacuum in the presence of strange quarks. Chiral perturbation theory allows to study reactions of pions and kaons and to further…
We use both old and new theoretical developments in QCD dispersion relation constraints on the scalar form factor in the decay K --> \pi l \nu_l to obtain constraints on the strange quark mass. The perturbative QCD side of the calculation…
Equal time, point to point correlation functions for spatially separated meson currents are calculated with respect to a variational construct for the ground state of QCD. Given such an ansatz we make no further approximations in the…
Unphysical effects associated with finite lattice spacing and partial quenching generally lead to to the presence of unphysical terms in chiral extrapolation formulae, which must be removed to make physical predictions. We use mixed action…
We develop a "variational mass" expansion approach, recently introduced in the Gross--Neveu model, to evaluate some of the order parameters of chiral symmetry breakdown in QCD. The method relies on a reorganization of the usual perturbation…
We investigate in some detail a "variational mass" expansion approach, generalized from a similar construction developed in the Gross-Neveu model, to evaluate the basic order parameters of the dynamical breaking of the $SU(2)_L \times…
We review the large Nc behavior of light scalar and vector resonances generated from unitarized meson-meson scattering amplitudes at one loop in Chiral Perturbation Theory. The vectors nicely follow the behavior expected for qqbar states,…
A metastable phase has important physical implications, since it may form vacuum bubbles detectable experimentally, whereas an unstable vacuum instantly explodes. It is well known, due to chiral symmetry breaking, there are at least two…
We extend our previous formulation of low-energy QCD in terms of an effective lagrangian containing operators of dimensionality $d\le 6$ constructed with pseudoscalars and quark fields, describing physics below the scale of chiral symmetry…
We introduce the quark virtuality distribution [$\lambda^{2}_{q}(x)$] as an extenson of the quark virtuality by using nonlocal rather than local quark vacuum condensates. Our results show that the quark virtuality distribution decreases…
The scalar susceptibility (chi_s) of QCD, which represents the response of the chiral condensate to a small perturbation of explicit chiral-symmetry breaking, is investigated within the nonlocal chiral quark model (NLchiQM) based on the…
We study the relation between the scale of chiral symmetry spontaneously breaking and constituent quark mass. We argue that this relation partly reveals strong interaction origination of chiral symmetry breaking. We show that the relation…
In this talk, which popularizes some of our recent work, we provide novel insights into the bulk properties of light chiral quarks in a fixed Euclidean volume (e.g. lattice QCD). We show that the spontaneous breakdown of chiral symmetry…
Previous work relating the flavour variation of the chiral order parameters $F_\pi$, $<\bar u u>$ and S-wave scattering data, based on chiral sum rules and chiral perturbation theory at order $p^4$, is extended to include $O(p^6)$…
We study the chiral dynamics of vector mesons in two-flavor QCD in vacuum by utilizing a functional renormalization group approach. This allows us to capture the dynamical transition from the quark-gluon phase at high energies to the…
We discuss the vector meson masses within the context of Chiral Perturbation Theory performing an expansion in terms of the momenta, quark masses and 1/Nc. We extend the previous analysis to include isospin breaking effects and also include…
We discuss scalar mesons properties on the light of chiral dynamics. Considering them as the chiral partners of pseudo-scalar mesons we propose an explanation to their unusual properties based on non-trivial vacuum effects coming from the…
We study SU(3)$_L\timesSU(3)_R$ chiral quark model of mesons up to the next to leading order of $1/N_c$ expansion. Composite vector and axial-vector mesons resonances are introduced via non-linear realization of chiral SU(3) and vector…
Expressions for the Wick contractions contributing to the scalar pion form-factor were computed model-independently in chiral perturbation theory at next-to-leading order. The results reveal correlations amongst the different contractions…