Koichi Hattori

We derive relativistic hydrodynamic equations with a dynamical spin degree of freedom on the basis of an entropy-current analysis. The first and second laws of local thermodynamics constrain possible structures of the constitutive relations including a spin current and the antisymmetric part of the (canonical) energy-momentum tensor. Solving the obtained hydrodynamic equations within the linear-mode analysis, we find spin-diffusion modes, indicating that spin density is damped out after a charac

We derive a quantum kinetic theory for fermions with arbitrary mass in a background electromagnetic field using a Wigner-function approach. Since spin of massive fermions is a dynamical degree of freedom (d.o.f.), kinetic equations with leading-order quantum corrections describe entangled dynamics of not only vector- and axial-charge distributions but also of the spin polarization. Therefore, we obtain one scalar and one axial-vector kinetic equations with magnetization currents pertinent to the

We compute the electrical conductivity of quark-gluon plasma in a strong magnetic field $B$ with quantum field theory at finite temperature using the lowest Landau level approximation. We provide the one-loop result arising from 1-to-2 scattering processes of which the kinematics are satisfied by the ($1+1$)-dimensional fermion dispersion relation. Because of the chirality conservation, the conductivity diverges in the massless limit and is sensitive to the value of the current quark mass. As a

We compute the longitudinal electrical conductivity in the presence of a strong background magnetic field in complete leading order of perturbative QCD, based on the assumed hierarchy of scales ${\ensuremath{\alpha}}_{s}eB\ensuremath{\ll}({m}_{q}^{2},{T}^{2})\ensuremath{\ll}eB$. We formulate an effective kinetic theory of lowest Landau level quarks with the leading order QCD collision term arising from 1-to-2 processes that become possible due to $1+1$ dimensional Landau level kinematics. In the

We investigate the viscosities of the quark-gluon plasma in strong magnetic fields within the leading-log and lowest Landau level (LLL) approximations. We first show that the bulk viscosity in the direction parallel to the magnetic field is the only component that has a contribution from the quarks occupying the LLL. We then compute the bulk viscosity from the Kubo formula and find an intriguing quark-mass dependence as a consequence of a competition between the suppression of the bulk viscosity

We show that the Kondo effect occurs in light quark matter which contains heavy quarks as impurities. We consider a scattering between a heavy-flavor impurity and a light quark near a Fermi surface which is mediated by gluon-exchange interactions. We find that the scattering amplitude has a logarithmic infrared divergence originating from imperfect cancellation between quark-impurity and hole-impurity scatterings in a loop integral, implying the presence of a strongly coupled regime near the Fer

We study relativistic hydrodynamics with chiral anomaly and dynamical electromagnetic fields, namely chiral magnetohydrodynamics (CMHD). We formulate CMHD as a low-energy effective theory based on a generalized derivative expansion. We demonstrate that the modification of ordinary magnetohydrodynamics (MHD) due to chiral anomaly can be obtained from the second law of thermodynamics and is tied to the chiral magnetic effect. We further study the real-time properties of a chiral fluid by solving l

Relativistic magnetohydrodynamics (RMHD) provides an extremely useful description of the low-energy long-wavelength phenomena in a variety of physical systems from quark–gluon plasma in heavy-ion collisions to matters in supernova, compact stars, and early universe. We review the recent theoretical progresses of RMHD, such as a formulation of RMHD from the perspective of magnetic flux conservation using the entropy–current analysis, the nonequilibrium statistical operator approach applied to qua

We investigate novel transport phenomena in a chiral fluid originated from an interplay between a vorticity and strong magnetic field, which induces a redistribution of vector charges in the system and an axial current along the magnetic field. The corresponding transport coefficients are obtained from an energy-shift argument for the chiral fermions in the lowest Landau level due to a spin-vorticity coupling and also from diagrammatic computations on the basis of the linear response theory. Bas

We obtain the general expression of the gluon propagator at finite temperature ($T$) and in a magnetic field ($B$), for the case that the four transverse tensor structures appear in the gluon self-energy. By using this expression and a specific form of the one-loop gluon self-energy in the lowest Landau level approximation, we analyze the gluon spectrum in the strong magnetic field limit. As a result, we find that there exist two collective excitations of which the energies are of the order of $

We show that effective coupling strengths between ungapped and gapped quarks in the two-flavor color superconducting (2SC) phase are renormalized by logarithmic quantum corrections. We obtain a set of coupled renormalization-group (RG) equations for two distinct effective coupling strengths arising from gluon exchanges carrying different color charges. The diagram of RG flow suggests that both of the coupling strengths evolve into a strong-coupling regime as we decrease the energy scale toward t

Patients with coronavirus disease-2019 (COVID-19) have an increased risk of thrombosis and acute respiratory distress syndrome (ARDS). Thrombosis is often attributed to increases in plasminogen activator inhibitor-1 (PAI-1) and a shut-down of fibrinolysis (blood clot dissolution). Decreased urokinase-type plasminogen activator (uPA), a protease necessary for cell-associated plasmin generation, and increased tissue-type plasminogen activator (tPA) and PAI-1 levels have been reported in COVID-19 p