Related papers: Anomalous $U(1)_A$ couplings and the Columbia plot
We show that one can describe the quark and lepton masses with a single anomaly-free U(1) flavor symmetry provided a single order one parameter is enhanced by roughly 4-5. The flavor symmetry can be seen to arise from inside the $E_6$…
We study three flavour chiral perturbation theory in a limit where the strange quark mass is much larger than the external momenta and the up and down quark masses, and where the external fields are those of two-flavour chiral perturbation…
We study the thermal transition of QCD with two degenerate light flavours by lattice simulations using $O(a)$-improved Wilson quarks. Temperature scans are performed at a fixed value of $N_t = (aT)^{-1}=16$, where $a$ is the lattice spacing…
We investigate the finite-temperature phase structure and the scaling of the chiral condensate in lattice QCD with two degenerate light quarks, using a renormalization group improved gauge action and the Wilson quark action. We obtain a…
Remarkable feature of new first-order phase transitions of gas-liquid gas-crystal types in combination with traditional solid-liquid transition are under consideration in a modified one-component plasma model (OCP) with uniform, but…
We discuss the confining and chiral-symmetry breaking properties of QCD with a large number of flavors $N_f$. In a Monte Carlo simulation of QCD with $N_f =16$ staggered fermions, we find clear evidence of a first order bulk phase…
Over the past few years three dimensional Quantum Electrodynamics (QED$_3$) has attracted a lot of attention, because it may be an effective theory for the underdoped and non-superconducting region of the phase diagram of high $T_c$ cuprate…
One flavor QCD is a rather intriguing variation on the underlying theory of hadrons. In this case quantum anomalies remove all chiral symmetries. This paper discusses the qualitative behavior of this theory as a function of its basic…
We investigate the nature of the chiral phase transition in the massless two-flavor QCD using the renormalization group improved gauge action and the Wilson quark action on $32^3\times 16$, $24^3\times 12$, and $16^3\times 8$ lattices. We…
We investigate the phase structure of lattice QCD for general number of flavors $N_F$. Based on numerical results combined with the result of the perturbation theory we propose the following picture: When $N_F \ge 17$, there is only a…
The nature of chiral phase transition of massless two flavor QCD depends on the fate of flavor singlet axial symmetry $U_A(1)$ at the critical temperature ($T_c$). Assuming that a finite $U_A(1)$ breaking remains at $T_c$, the corresponding…
Chiral anomaly is a key feature of Lorentz-invariant quantum field theories: in presence of parallel external electric and magnetic fields, the number of massless Weyl fermions of a given chirality is not conserved. In condensed matter,…
A promising approach to the Standard Model flavor puzzle is based on the idea that the $SU(3)^3$ quark-flavor symmetry is spontaneously broken by vacuum expectation values of `Yukawa fields' which minimize the symmetry invariant scalar…
We argue that the order of the chiral transition for N_f=2 is a sensitive probe of the QCD vacuum, in particular of the mechanism of color confinement. A strategy is developed to investigate the order of the transition by use of finite size…
We construct a model for the quark mass and flavor mixing matrices, based on the hypothesis that the flavor weak eigenstates in the three families are distinguished by a spontaneously broken discrete $Z_6$ chiral symmetry. In a leading…
We discuss the role of the U(1) axial symmetry for the scalar and pseudoscalar meson mass spectrum of QCD at finite temperature, above the chiral transition at T_c, using a chiral effective Lagrangian model, which, in addition to the usual…
We review recent results on the role of light quark states within the QCD phase diagram. In particular, we will discuss how the combined use of theoretical techniques such as Effective Theories, Unitarization and Ward Identities helps to…
It is commonly believed that in confining vector-like gauge theories the center and chiral symmetry realizations are parametrically entangled, and if phase transitions occur, they must take place around the strong scale $\Lambda^{-1}$ of…
We investigate the chiral phase transition in the soft-wall model of AdS/QCD at zero chemical potential for two-flavor and three-flavor cases, respectively. We show that there is no spontaneous chiral symmetry breaking in the original…
We study the $U(1)_A$ anomaly in two-flavor lattice QCD at finite temperature with the M\"obius domain-wall Dirac operator. We generate gauge configurations in the temperature range $(0.9, 1.2) T_c$ on different physical volumes, $L=$ 2--4…