We discuss the phase structure of dense matter, in particular the nature of the transition between hadronic and quark matter. Calculations within a Ginzburg-Landau approach show that the axial anomaly can induce a critical point in this transition region. This is possible because in three-flavor quark matter with instanton effects a chiral condensate can be added to the color-flavor locked (CFL) phase without changing the symmetries of the ground state. In (massless) two-flavor quark matter such a critical point is not possible since the corresponding color superconductor (2SC) does not break chiral symmetry. We study the effects of a nonzero but finite strange quark mass which interpolates between these two cases. Since at ultra-high density the first reaction of CFL to a nonzero strange quark mass is to develop a kaon condensate, we extend previous Ginzburg-Landau studies by including such a condensate. We discuss the fate of the critical point systematically and show that the continuity between hadronic and quark matter can be disrupted by the onset of a kaon condensate. Moreover, we identify the mass terms in the Ginzburg-Landau potential which are needed for the 2SC phase to occur in the phase diagram.
We consider static scalar fields coupled to the gradient where the coupling also appears in next-to-leading order Ginzburg-Landau models. We study condensation behaviors of scalar fields outside regular compact reflecting stars in the asymptotically flat background. For non-negative coupling parameters, we prove that the reflecting star cannot support coupled static scalar fields.
We study the interaction between the vortices in multi components superconductors based on the Jacobs and Rebbi variation method using Ginzburg-Landau theory. With one condensation, we get attraction interaction between the vortices for type I and repulsion for type II superconductors. With two condensation states such as Mg B_{2} superconductors the behavior is quite different. There is attraction at large distances and repulsion when the vortices are close to each other. A stability point at distance 2.7/λ_{1} is obtained. In the case of three condensation states such as iron based supercond…
The core of neutron-star matter is supposed to be at a much higher density than the normal nuclear matter density for which various possibilities have been suggested such as, for example, meson or hyperon condensation and/or deconfined quark or color-superconducting matter. In this work, we explore the implication on hadron physics of a dense compact object that has three "phases", nuclear matter at the outer layer, kaon condensed nuclear matter in the middle and strange quark matter at the core. Using a drastically simplified but not unreasonable model, we develop the scenario where the diffe…
We study how a chiral tricritical point (TCP) on QCD phase diagram is affected by the imbalance of up and down quark densities (isospin density), using the generalized Ginzburg-Landau (GL) approach. The resulting phase diagram near TCP shows a rich fine structure which includes inhomogeneities of both the chiral and the charged pion condensations. It turns out that the TCP splits into multicritical points.
We consider three-flavor chiral perturbation theory ($χ$PT) at zero temperature and nonzero isospin ($μ_{I}$) and strange ($μ_{S}$) chemical potentials. The effective potential is calculated to next-to-leading order (NLO) in the $π^{\pm}$-condensed phase, the $K^{\pm}$-condensed phase, and the $K^0/\bar{K}^0$-condensed phase. It is shown that the transitions from the vacuum phase to these phases are second order and take place when, $|μ_I|=m_π$, $|{1\over2}μ_I+μ_S|=m_K$, and $|-{1\over2}μ_I+μ_S|=m_K$, respectively at tree level and remains unchanged at NLO. The transition between the two conde…
We give a pedagogical review of the properties of the various meson condensation phases triggered by a large isospin or strangeness imbalance. We argue that these phases are extremely interesting and powerful playground for exploring the properties of hadronic matter. The reason is that they are realized in a regime in which various theoretical methods overlap with increasingly precise numerical lattice QCD simulations, providing insight on the properties of color confinement and of chiral symmetry breaking.
The present status in the field of strange mesons in nuclei and neutron stars is reviewed. In particular, the $\bar K N$ interaction, that is governed by the presence of the $Λ(1405)$, is analyzed and the formation of the $\bar K NN$ bound state is discussed. Moreover, the properties of $\bar K$ in dense nuclear matter are studied, in connection with strangeness production in nuclear collisions and kaon condensation in neutron stars.
We analyze various aspects of pion and kaon condensation in the framework of chiral perturbation theory. Considering a system at vanishing temperature and varying the isospin chemical potential and the strange quark chemical potential we reproduce known results about the phase transition to the pion condensation phase and to the kaon condensation phase. However, we obtain mesonic mixings and masses in the condensed phases that are in disagreement with the results reported in previous works. Our findings are obtained both by a theory group analysis and by direct calculation by means of the same…
In this work pion and kaon condensation in the framework of chiral perturbation theory is studied. I consider a system at vanishing temperature with nonzero isospin chemical potential and strangeness chemical potential; meson masses and mixing in the normal phase, the pion condensation phase and the kaon condensation phase are described. There are differences with previous works, but the results presented here are supported by both theory group analysis and by direct calculations. Some pion decay channels in the normal and the pion condensation phases are studied, finding a nonmonotonic behavi…
QCD at finite isospin chemical potential $μ_{\text I}$ possesses a positively definite fermion determinant and the lattice simulation can be successfully performed. While the two-flavor effective models may be sufficient to describe the phenomenon of pion condensation, it is interesting to study the roles of the strangeness degree of freedom and the U$_{\rm A}(1)$ anomaly. In this paper, we present a systematic study of the three-flavor Nambu--Jona-Lasinio model with a Kobayashi-Maskawa-'t Hooft (KMT) term that mimics the U$_{\rm A}(1)$ anomaly at finite isospin chemical potential. In the mean…
Dense quark matter is expected to behave as a type-II superconductor at strong coupling. It was previously shown that if the strange quark mass $m_s$ is neglected, magnetic domain walls in the so-called 2SC phase are the energetically preferred magnetic defects in a certain parameter region. Computing the flux tube profiles and associated free energies within a Ginzburg-Landau approach, we find a cascade of multi-winding flux tubes as "remnants" of the domain wall when $m_s$ is increased. These flux tubes exhibit an unconventional ring-like structure of the magnetic field. We show that flux tu…
We investigate the effect of strange quark degrees of freedom on the formation of inhomogeneous chiral condensates in a three-flavor Nambu--Jona-Lasinio model in mean-field approximation. A Ginzburg-Landau study complemented by a stability analysis allow us to determine in a general way the location of the critical and Lifshitz points, together with the phase boundary where the (partially) chirally restored phase becomes unstable against developing inhomogeneities, without resorting to specific assumptions on the shape of the chiral condensate. We discuss the resulting phase structure and stud…
The nuclear symmetry energy figures crucially in the structure of asymmetric nuclei and, more importantly, in the equation of state (EoS) of compact stars. At present it is almost totally unknown, both experimentally and theoretically, in the density regime appropriate for the interior of neutron stars. Basing on a strong-coupled structure of dense baryonic matter encoded in the skyrmion crystal approach with a topology change and resorting to the notion of generalized HLS (hidden local symmetry) in hadronic interactions, we address a variety of hitherto unexplored issues of nuclear interactio…
Near the flavor SU(3) limit, we propose an analytical description for color-flavor-locked-type Bardeen-Cooper-Schrieffer (BCS) phase in the Nambu Jona-Lasinio (NJL) model. The diquark behaviors in light-flavor and strange-flavor-involved channels and Bose-Einstein condensation (BEC) of bound diquark states are studied. When the attractive interaction between quarks is strong enough, a BCS-BEC crossover is predicted in the environment with color-flavor-locked pairing pattern. The resulting Bose-Einstein condensed phase is found to be an intergrade phase before the emergence of the previous-pred…
We investigate the QCD phase diagram for small values of baryon and strange quark chemical potentials from simulations at non-zero isospin chemical potential. Simulations at pure isospin chemical potential are not hindered by the sign problem and pion condensation can be observed for sufficiently large isospin chemical potentials. We study how the related phase boundary evolves with baryonic and strange chemical potentials via reweighting in quark chemical potentials and discuss our results. Furthermore, we propose and implement an alternative method to approach nonzero baryon (and strange qua…
We investigate the rotating quark matter in the three-flavor Nambu and Jona-Lasinio (NJL) model. The chiral condensation, spin polarization and number susceptibility of the light and strange quarks are carefully studied at finite temperature without or with finite chemical potential in this model. We find that the rotation suppresses the chiral condensation and enhances the first-order quark spin polarization, however for the second-order quark spin polarization and quark number susceptibility the effect is complicated and interesting. When extending to the situation with finite chemical poten…
In this paper, we study the possibility of an inhomogeneous quark condensate in the 1+1 dimensional Nambu-Jona-Lasinio model in the large-$N_c$ limit at finite temperature $T$ and quark chemical potential $μ$ using dimensional regularization. The phase diagram in the $μ$--$T$ plane is mapped out. At zero temperature, an inhomogeneous phase with a chiral-density wave exists for all values of $μ>μ_c$. Performing a Ginzburg-Landau analysis, we show that in the chiral limit, the critical point and the Lifschitz point coincide. We also consider the competition between a chiral-density wave and a co…
We study pion and kaon condensation using three-flavor chiral perturbation theory at finite isospin and strangeness quark chemical potentials μI and μS . The phase diagram consists of a vacuum phase and three distinct Bose condensed phases with condensates of charged pions as well as charged and neutral kaons. Adding electromagnetic interactions, a phase with a charged condensate becomes a Higgs phase and the resulting phase diagram is modified due to the electromagnetic mass splittings of the mesons. The results for the pion-condensed phase are applied to calculate mass-radius relation of pio…
We study strange and isospin asymmetric matter in a bottom-up AdS/QCD model. We first consider isospin matter, which has served as a good testing ground for nonperturbative QCD. We calculate the isospin chemical potential dependence of hadronic observables such as the masses and the decay constants of the pseudo-scalar, vector, and axial-vector mesons. We discuss a possibility of the charged pion condensation in the matter within the bottom-up AdS/QCD model. Then, we study the properties of the hadronic observables in strange matter. We calculate the deconfinement temperature in strange and is…
Extensive study of phase diagram for charge neutral homogeneous quark matter affected by dynamical chiral condensation -- unified picture for thermal unpairing transitions from weak to strong coupling --
The occurrence of spontaneous chiral symmetry breaking (SChSB) is equivalent to sufficient abundance of Dirac near-zeromodes. However, dynamical mechanism leading to breakdown of chiral symmetry should be naturally reflected in chiral properties of the modes. Here we offer such connection, presenting evidence that SChSB in QCD proceeds via the appearance of modes exhibiting dynamical tendency for local chiral polarization. These modes form a band of finite width Lambda_ch (chiral polarization scale) around the surface of otherwise anti--polarized Dirac sea, and condense. Lambda_ch characterize…
This paper describes dynamic and thermodynamic (at $T=0$) properties of mesons in asymmetric matter in the framework of Chiral Perturbation Theory. We consider a mesonic system at vanishing temperature with nonzero isospin chemical potential and strangeness chemical potential and we study their effect on the phase diagram. We also study meson masses and mixing in the resulting normal phase, pion condensation phase and kaon condensation phase. We find differences with previous papers regarding meson masses and mixing in the condensed phases; the results presented here are supported by theory gr…
For the first time, a reliable estimation for the equations of state (EoS), bulk viscosity, and relaxation time, at temperatures ranging from a few MeV up to TeV or energy density up to $10^{16}~$GeV/fm$^3$. This genuine study covers both strong and electroweak epochs of the early Universe. Non--perturbation (up, down, strange, charm, and bottom quark flavor) and perturbative calculations (up, down, strange, charm, bottom, and top quark flavors), are phenomenologically combined, at vanishing baryon--chemical potential. In these results, calculations from Polyakov linear--sigma model (PLSM) of …
