Maxim Chernodub

Superconductivity of QCD vacuum in strong magnetic field

We show that in a sufficiently strong magnetic field the QCD vacuum may undergo a transition to a new phase where charged rho(+/-) mesons are condensed. In this phase the vacuum behaves as an anisotropic inhomogeneous superconductor which supports superconductivity along the axis of the magnetic field. In the directions transverse to the magnetic field the superconductivity is absent. The magnetic-field-induced anisotropic superconductivity-which is realized in the cold vacuum, i.e. at zero temperature and density-is a consequence of a nonminimal coupling of the rho mesons to the electromagnetic field. The onset of the superconductivity of the charged rho(+/-) mesons should also induce an inhomogeneous super-fluidity of the neutral rho(0) mesons. We also argue that due to simple kinematical reasons a strong enough magnetic field makes the lifetime of the rho mesons longer by closing the main channels of the strong decays of the rho mesons into charged pions.

Spontaneous electromagnetic superconductivity of vacuum in a strong magnetic field: evidence from the Nambu-Jona-Lasinio model

Using an extended Nambu-Jona-Lasinio model as a low-energy effective model of QCD, we show that the vacuum in a strong external magnetic field (stronger than 10(16)   T) experiences a spontaneous phase transition to an electromagnetically superconducting state. The unexpected superconductivity of, basically, empty space is induced by emergence of quark-antiquark vector condensates with quantum numbers of electrically charged rho mesons. The superconducting phase possesses an anisotropic inhomogeneous structure similar to a periodic Abrikosov lattice in a type-II superconductor. The superconducting vacuum is made of a new type of vortices which are topological defects in the charged vector condensates. The superconductivity is realized along the axis of the magnetic field only. We argue that this effect is absent in pure QED.

Phase diagram of hot QCD in an external magnetic field: Possible splitting of deconfinement and chiral transitions

The structure of the phase diagram for strong interactions becomes richer in the presence of a magnetic background, which enters as a new control parameter for the thermodynamics. Motivated by the relevance of this physical setting for current and future high-energy heavy-ion collision experiments and for the cosmological QCD transitions, we use the linear sigma model coupled to quarks and to Polyakov loops as an effective theory to investigate how the chiral and the deconfining transitions are affected, and present a general picture for the temperature--magnetic field phase diagram. We compute and discuss each contribution to the effective potential for the approximate order parameters, and uncover new phenomena such as the paramagnetically induced breaking of global

Magnetic-field-induced insulator-conductor transition in SU(2) quenched lattice gauge theory.

{\mathbb{Z}}_{3}

Numerical study of chiral symmetry breaking in non-Abelian gauge theory with background magnetic field

symmetry, and possible splitting of deconfinement and chiral transitions in a strong magnetic field.

Electromagnetic superconductivity of vacuum induced by strong magnetic field: Numerical evidence in lattice gauge theory

We study the correlator of two vector currents in quenched SU(2) lattice gauge theory with a chirally invariant lattice Dirac operator with a constant external magnetic field. It is found that in the confinement phase the correlator of the components of the current parallel to the magnetic field decays much slower than in the absence of a magnetic field, while for other components the correlation length slightly decreases. We apply the maximal entropy method to extract the corresponding spectral function. In the limit of zero frequency this spectral function yields the electric conductivity of quenched theory. We find that in the confinement phase the external magnetic field induces nonzero electric conductivity along the direction of the field, transforming the system from an insulator into an anisotropic conductor. In the deconfinement phase the conductivity does not exhibit any sizable dependence on the magnetic field.

Condensed matter realization of the axial magnetic effect

Abstract We investigate the effect of a uniform background magnetic field on the chiral symmetry breaking in SU ( 2 ) Yang–Mills theory on the lattice. We observe that the chiral condensate grows linearly with the field strength B up to e B = 3 GeV as predicted by chiral perturbation theory for full QCD. As the temperature increases the coefficient in front of the linear term gets smaller. In the magnetic field near-zero eigenmodes of the Dirac operator tend to have more regular structure with larger (compared to zero-field case) Hausdorff dimensionality. We suggest that the delocalization of near-zero eigenmodes plays a crucial role in the enhancement of the chiral symmetry breaking.

Quark electric dipole moment induced by magnetic field

Abstract Using numerical simulations of quenched SU ( 2 ) gauge theory we demonstrate that an external magnetic field leads to spontaneous generation of quark condensates with quantum numbers of electrically charged ρ mesons if the strength of the magnetic field exceeds the critical value e B c = 0.927 ( 77 ) GeV 2 or B c = ( 1.56 ± 0.13 ) ⋅ 10 16 Tesla . The condensation of the charged ρ mesons in strong magnetic field is a key feature of the magnetic-field-induced electromagnetic superconductivity of the vacuum.

Electromagnetically superconducting phase of the vacuum in a strong magnetic field: Structure of superconductor and superfluid vortex lattices in the ground state

The axial magnetic effect, i.e., the generation of an energy current parallel to an axial magnetic field coupling with opposite signs to left- and right-handed fermions is a non-dissipative transport phenomenon intimately related to the gravitational contribution to the axial anomaly. An axial magnetic field is naturally realized in condensed matter in the so called Weyl semi-metals. We show that the edge states of a Weyl semimetal at finite temperature possess a temperature dependent angular momentum in the direction of the vector potential intrinsic to the system. Such a condensed matter realization provides a plausible context for the experimental confirmation of the elusive gravitational anomaly.

Numerical evidence of the axial magnetic effect

We show numerically that quarks develop an electric dipole moment in the direction of a sufficiently intense magnetic field due to local fluctuations of topological charge. This anomalous CP-odd effect is a spin analogue of the chiral magnetic effect in QCD.