arXiv subjects

Kazuya Mameda

Publications and source records attributed to Kazuya Mameda.

24 records · Page 2Linked to original sources

arXiv2017

Surface Magnetic Catalysis

We study fermions in a magnetic field in a finite size cylinder. With the boundary condition for the fermion flux, we show that the energy spectra and the wave-functions are modified by the finite size effect; the boundary makes the degenerate Landau levels appear only partially for states with small angular momenta, while the boundary effect becomes stronger for states with large angular momenta. We find that mode accumulation at the boundary occurs for large angular momenta and the magnetic effect is enhanced on the boundary surface. Using a simple fermionic model, we quantify the magnetic catalysis, i.e. the magnetic enhancement of the fermion pair condensation, in a finite size cylinder. We confirm that the magnetic catalysis is strongly amplified at the boundary due to the mode accumulation.

hep-ph↗

arXiv2016

Boundary effects and gapped dispersion in rotating fermionic matter

We discuss the importance of boundary effects on fermionic matter in a rotating frame. By explicit calculations at zero temperature we show that the scalar condensate of fermion and anti-fermion cannot be modified by the rotation once the boundary condition is properly implemented. The situation is qualitatively changed at finite temperature and/or in the presence of a sufficiently strong magnetic field that supersedes the boundary effects. Therefore, to establish an interpretation of the rotation as an effective chemical potential, it is crucial to consider further environmental effects such as the finite temperature and magnetic field.

hep-ph↗

arXiv2016

Magnetism and rotation in relativistic field theory

We investigate the analogy between magnetism and rotation in relativistic theory. In nonrelativistic theory, the exact correspondence between magnetism and rotation is established in the presence of an external trapping potential. Based on this, we analyze relativistic rotation under external trapping potentials. A Landau-like quantization is obtained by considering an energy-dependent potential.

hep-th↗

arXiv2016

Analogy between rotation and density for Dirac fermions in a magnetic field

We analyse the energy spectra of Dirac fermions in the presence of rotation and magnetic field. We find that the Landau degeneracy is resolved by rotation. A drastic change in the energy dispersion relation leads to the "rotational magnetic inhibition" that is a novel phenomenon analogous to the inverse magnetic catalysis in a magnetic system at finite chemical potential.

hep-ph↗

arXiv2015

QCD $θ$-vacua from the chiral limit to the quenched limit

We investigate the dependence of the QCD vacuum structure on the $θ$-angle and quark mass, using the Di-Vecchia--Veneziano model. Although the Di-Vecchia--Veneziano model is a chiral effective model, it contains the topological properties of the pure Yang--Mills theory. It is shown that within this model, the ground state energies for all $θ$ are continuous functions of quark mass from the chiral limit to the quenched limit, even including the first order phase transition at $θ= π$. Based on this effective model, we discuss (i) how the ground state depends on quark mass, and (ii) why the phase transition at $θ= π$ is present both in the chiral and quenched limit. In order to analyze the relation between quark mass and the $θ$-vacua, we calculate the chiral condensate as a function of quark mass. Also, considering the presence of the innate metastable states included in the QCD $θ$-vacuum, we also give a unified understanding of the phase transitions at $θ= π$ in the chiral and quenched limit.

hep-ph↗

arXiv2012

Wess-Zumino-Witten action and photons from the Chiral Magnetic Effect

We revisit the Chiral Magnetic Effect (CME) using the chiral Lagrangian. We demonstrate that the electric-current formula of the CME is derived immediately from the contact part of the Wess-Zumino-Witten action. This implies that the CME could be, if observed, a signature for the local parity violation, but a direct evidence for neither quark deconfinement nor chiral restoration. We also discuss the reverse Chiral Magnetic Primakoff Effect, i.e. the real photon production through the vertex associated with the CME, which is kinematically possible for space-time inhomogeneous configurations of magnetic fields and the strong theta angle. We make a qualitative estimate for the photon yield to find that it comparable to the thermal photon.

hep-ph↗