Using the chiral kinetic theory we derive the electric and chiral current densities in inhomogeneous relativistic plasma. We also derive equations for the electric and chiral charge chemical potentials that close the Maxwell equations in such a plasma. The analysis is done in the regimes with and without a drift of the plasma as a whole. In addition to the currents present in the homogeneous plasma (Hall current, chiral magnetic, chiral separation, and chiral electric separation effects, as well as Ohm's current) we derive several new terms associated with inhomogeneities of the plasma. Apart from various diffusion-like terms, we find also new dissipation-less terms that are independent of relaxation time. Their origin can be traced to the Berry curvature modifications of the kinetic theory.

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We study magnetogenesis in axionlike inflation driven by a pseudoscalar field φ coupled axially to the electromagnetic (EM) field (β/Mp)φFµνF µν with dimensionless coupling constant β. A set of equations for the inflaton field, scale factor, and expectation values of quadratic functions of the EM field is derived. These equations take into account the Schwinger effect and the backreaction of generated EM fields on the Universe expansion. It is found that the backreaction becomes important when the EM energy density reaches the value ρEM ∼ ( √ 2 /β)ρ inf ( is the slow-roll parameter and ρ inf is the energy density of the inflaton) slowing down the inflaton rolling and terminating magnetogenesis. The Schwinger effect becomes relevant when the electric energy density exceeds the value ρE ∼ α −3 EM (ρ 2 tot /M 4 p ), where ρtot = 3H 2 M 2 p is the total energy density and αEM is the EM coupling constant. For large β, produced charged particles could constitute a significant part of the Universe energy density even before the preheating stage. Numerically studying magnetogenesis in the α-attractor model of inflation, we find that it is possible to generate helical magnetic fields with the maximal strength 10 −15 G, however, only with the correlation length of order 1 pc at present.

We study the generation of electromagnetic fields during inflation when the conformal invariance of Maxwell's action is broken by the kinetic coupling f 2 (φ)FµνF µν of the electromagnetic field to the inflaton field φ. We consider the case where the coupling function f (φ) decreases in time during inflation and, as a result, the electric component of the energy density dominates over the magnetic one. The system of equations which governs the joint evolution of the scale factor, inflaton field, and electric energy density is derived. The backreaction occurs when the electric energy density becomes as large as the product of the slow-roll parameter ǫ and inflaton energy density, ρE ∼ ǫρ inf . It affects the inflaton field evolution and leads to the scale-invariant electric power spectrum and the magnetic one which is blue with the spectral index nB = 2 for any decreasing coupling function. This gives an upper limit on the present-day value of observed magnetic fields below 10 −22 G. It is worth emphasizing that since the effective electric charge of particles e eff = e/f is suppressed by the coupling function, the Schwinger effect becomes important only at the late stages of inflation when the inflaton field is close to the minimum of its potential. The Schwinger effect abruptly decreases the value of the electric field, helping to finish the inflation stage and enter the stage of preheating. It effectively produces the charged particles, implementing the Schwinger reheating scenario even before the fast oscillations of the inflaton. The numerical analysis is carried out in the Starobinsky model of inflation for the powerlike f ∝ a α and Ratra-type f = exp(βφ/Mp) coupling functions.

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Motivated by a recent experiment [K. C. Wright et al., Phys. Rev. Lett. 110, 025302 (2013)], we investigate deterministic discontinuous jumps between quantized circulation states in a toroidally trapped Bose-Einstein condensate. These phase slips are induced by vortex excitations created by a rotating weak link. We analyze the influence of a localized condensate density depletion and atomic superflows, governed by the rotating barrier, on the energetic and dynamical stability of the vortices in the ring-shaped condensate. We simulate in a three-dimensional dissipative mean-field model the dynamics of the condensate using parameters similar to the experimental conditions. Moreover, we consider the dynamics of the stirred condensate far beyond the experimentally explored region and reveal surprising manifestations of complex vortex dynamics.

By assuming the kinetic coupling f 2 (φ)F F of the effective inflaton field φ with the electromagnetic field, we explore magnetogenesis during the inflation and preheating stages in the R 2 Starobinsky model [1]. We consider the case of the exponential coupling function f (φ) = exp(αφ/Mp) and show that for α ∼ 12 − 15 it is possible to generate the large scale magnetic fields with strength 10 −15 Gauss at the present epoch. The spectrum of generated magnetic fields is blue with the spectral index n = 1+s, s > 0. We have found that for the relevant values of the coupling parameter, α = 12 − 15, model avoids the back-reaction problem for all relevant modes.

Motivated by a recent experiment [S. Beattie, S. Moulder, R. J. Fletcher, and Z. Hadzibabic, PRL 110, 025301 (2013)] we study the superflow of atomic spinor Bose-Einstein condensates optically trapped in a ring-shaped geometry. Within a dissipative mean-field approach we simulate a twocomponent condensate in conditions adapted to the experiment. In qualitative agreement with the experimental findings, we observe persistent currents, if the spin-population imbalance is above some well-defined 'critical' value. The triply charged vortices decay in quantized steps. The vortex lines escape from the center of the ring through dynamically created regions in the condensate annulus with reduced density of one component filled by atoms of the other component. The vortices then leave the ring-shaped high density region of the condensate and finally decay into elementary excitations. Persistent currents or 'flows without friction' as a hallmark of superfluidity have been studied in liquid helium for several decades. Recently, persistent flow of atoms has been observed in Bose-Einstein condensates (BEC) trapped in a ring-like potential [1][2][3][4][5]. This enables fundamental studies of superfluidity and may lead to applications in high precision metrology and atomtronics. Of course, the question of the stability of the atomic persistent currents is of fundamental importance and, therefore, the subject of numerous investigations.Theoretical studies of persistent currents in atomic BEC are mostly limited to the simplified cases of one-dimensionality and very weak interactions. Onecomponent BECs in a one-dimensional (1D) ring potential were studied in Refs. [6] and [7]. Superfluidity on a 1D ring in the presence of impurities was investigated in Ref. [8]. Families of 2D solitary waves with and without singly-charged persistent flow are investigated in Ref. [9]. For two-component BECs in 1D or 2D traps, the stability of the persistent currents and their decay mechanisms were under investigation in Refs. [10][11][12][13][14][15][16]. Smyrnakis et al. [10] concluded that in a strictly one-dimensional ring persistent currents with circulation lager than one are stable only in single-component gases. This conclusion was challenged recently [17]. In Ref.[18] it was found on the basis of mean field calculations supported by exact diagonalization results, that persistent currents in 2D traps may be stable under specific conditions. Experimentally, this problem has been addressed very recently [5] for a toroidally trapped gas of 87 Rb atoms in two different spin states. However, previous theoretical investigations describe the stability of the persistent currents in spinor BEC only qualitatively, but do not elucidate the microscopic mechanism of the instabilities and its impact on the dynamics of the persistent currents.In the present work, we investigate the stability of the superflow within a two-dimensional dissipative meanfield theory. We find that phase-slips occur as the result of the simultaneous action of two factors: an azim...