The chiral phase transition at high temperature and/or density is interpreted in terms of Georgi’s vector limit. We discuss three cases as possible support for this scenario: Quark-number susceptibility, cool kaons in heavy-ion process and an instanton-molecule picture for chiral restoration. Both the notion of “mended symmetry” and the Georgi vector limit are suggested to be relevant in nuclea...

We show on the basis of an effective theory of QCD that a wide variety of observables in the hadron world is governed by the chiral symmetry together with an interplay between the axial anomaly and the explicit symmetry breaking due to the current quark mass. We also discuss the nature of the chiral transition at finite temperature and related dynamical phenomena using the effective Lagrangian....

The vector manifestation (VM) was proposed as a novel manifestation of chiral symmetry in which the massless vector meson becomes the chiral partner of pion. In this write-up, I briefly summarize the following main ingredients to formulate the VM in hot and/or dense matter: Effective field theory (EFT) based on the hidden local symmetry; Wilsonian matching between the EFT and QCD; Intrinsic the...

We consider the Quasilocal Quark Model of NJL type including vector and axial-vector four-fermion interaction with derivatives. In the presence of a strong attraction in the scalar channel the chiral symmetry is spontaneously broken and as a consequence the composite meson states are generated in the vector and axialvector channels. The appropriate set of Chiral Symmetry Restoration Sum Rules i...

removes spurious selection rule forbidding processes with odd number of Goldstone mesons. Pseudoscalar mesons are produced in e+e− annihilation via vector resonances, hence one should include vector mesons in a chiral invariant way. The problem of testing chiral models of the vector meson interactions with Goldstone bosons is acute because in well studied decays ρ → 2π, ω → 3π the final pions a...

We develop quenched chiral perturbation theory for vector mesons made of light quarks, in the limit where the vector meson masses are much larger than the pion mass. We use this theory to extract the leading nonanalytic dependence of the vector meson masses on the masses of the light quarks. By comparing with analogous quantities computed in ordinary chiral perturbation theory, we estimate the ...

Discussion of the η → π 0 γγ decay within a chiral unitary approach We improve the calculations of the η → π 0 γγ decay within the context of meson chiral lagrangians. We use a chiral unitary approach for the meson-meson interaction, thus generating the a0(980) resonance and fixing the longstanding sign ambiguity on its contribution. This also allows us to calculate the loops with one vector me...

In this talk I summarize our recent works on the chiral symmetry restoration in the large flavor QCD using the hidden local symmetry (HLS) as an effective field theory of QCD. Bare parameters in the HLS are determined by matching the HLS with QCD at the matching scale through the Wilsoninan matching conditions. This Wilsonian matching leads to the vector manifestation of the Wigner realization ...

The nucleon’s strange-quark vector current form factors are studied from the perspective of chiral symmetry. It is argued that chiral perturbation theory cannot yield a prediction for the strangeness radius and magnetic moment. Arrival at definite predictions requires the introduction of additional, modeldependent assumptions which go beyond the framework of chiral perturbation theory. A variet...

We summarize recent developments in our understanding of low-mass quark-antiquark excitations in hadronic matter under various different conditions. This includes the ther-modynamics of the chiral condensate, pions as Goldstone bosons in normal nuclear matter, and excursions into extreme territory of the QCD phase diagram: lepton pair production from a fireball expanding through the transition ...