Related papers: Patterns and partners within the QCD phase diagram…
We review recent developments in our understanding of the dynamics of strongly-coupled chiral $SU(N)$ gauge theories in four dimensions, problems which are potentially important in our quest to go beyond the standard $SU(3)_{QCD} \times…
We perform a global analysis of lattice and experimental data on negative-strangeness meson-baryon scattering using a large set of variations of the theoretical framework based on the Chiral Unitary Approach. For the former, the L\"uscher…
QCD string picture of highly excited hadrons very naturally explains parity doubling once the chiral symmetry is restored high in the spectrum. In particular, the spin-orbit and tensor interactions of quarks at the ends of the string,…
The study of QCD with two light dynamical fermions is of fundamental importance to understand the mechanism of color confinement. We present results of a numerical investigation on the order of the chiral phase transition with $N_f = 2$ by…
We analyze the dynamics of an $SU_L(2)\otimes U_R(1)$ chiral gauge theory on a lattice with a large multifermion coupling $1\ll g_2 < \infty$. It is shown that no spontaneous symmetry breaking occurs; the ``spectator'' fermion $\psi_R(x)$…
Chiral perturbation theory in the two--flavour sector allows one to analyse Green functions in QCD in the limit where the strange quark mass is considered to be large in comparison to the external momenta and to the light quark masses m_u…
I discuss several topics in the applications of chiral symmetry at nonzero temperature, including: where the rho goes, disoriented chiral condensates, and the phase diagram for $QCD$ with $2+1$ flavors. (Based upon talks presented at the…
Lattice QCD simulations with chirally symmetric quarks have recently established approximate $SU(2)_{CS}$ and $SU(2N_F)$ symmetries of the quantum effective action in a temperature range above the chiral crossover $T_\mathrm{ch}$, in which…
We discuss the fate of the axial U(1) symmetry in 2-flavor QCD at finite temperature, where the non-singlet chiral symmetry is restored. We first summarize the previous theoretical investigation on the relation between the eigenvalue…
Correlations of conserved charges, i.e., the baryon number, electric charge and the strangeness, have been calculated at finite temperature and chemical potential up to the fourth order. The calculations are done in a 2+1 flavor low energy…
The AdS/QCD models suggest an interesting idea that the effective theory of low-energy QCD may be formulated as a 5-dimensional field theory in the weak coupling regime in which the fifth coordinate plays a role of inverse energy scale.…
We study the $U(1)_A$ anomaly in the high-temperature phase of $N_f=2+1$ lattice QCD with chiral fermions. Gauge ensembles are generated with M\"obius domain-wall (MDW) fermions, and in the measurements the determinant is reweighted to that…
Two crucial properties of QCD, confinement and chiral symmetry breaking, cannot be understood within the context of conventional Feynman perturbation theory. Non-perturbative phenomena enter the theory in a fundamental way at both the…
Inequalities for QCD functional integrals are used to establish that up to certain technical assumptions. the high temperature chirally restored phase of QCD is effectively symmetric under $U(N_f) \times U(N_f)$ rather than $SU(N_f) \times…
The axial $U(1)$ symmetry in the high-temperature phase is investigated with $N_f = 2$ lattice QCD simulations. The gauge ensembles are generated with M\"obius domain-wall fermions, and the overlap/domain-wall reweighting is applied. We…
In these lectures I review some basic examples of how the concepts of universality and scaling can be used to study aspects of the chiral and the deconfinement transition, if not in QCD directly but in QCD-like theories. As an example for…
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…
We discuss chiral theories of constituent quarks interacting with bosons at high temperatures. In the chirally symmetric phase we demonstrate by applying functional methods the presence of effective anomalous couplings for e.g. $\pi \sigma…
Chiral symmetry restoration at nonzero temperature is studied in the framework of the O(4) linear sigma model and the U(N_f)_r x U(N_f)_l linear sigma model with N_f=2,3, and 4 quark flavors. We investigate the temperature dependence of the…
The important role played by chiral symmetry and axial anomaly in QCD in nuclear physics is reviewed. Some recent topics on possible chiral restoration in hot and/or dense matter are picked up. We also discuss so called {\em effective}…