We show that our Universe may be inhomogeneous on large sub-horizon scales without us being able to realise it. We assume that a network of domain walls permeates the universe dividing it in domains ...with slightly different vacuum energy densities. We require that the energy scale of the phase transition which produced the domain walls is sufficiently low so that the walls have a negligible effect on structure formation. Nevertheless, the different vacuum densities of different domains will lead to different values of the cosmological parameters
Ω
Λ
0
,
Ω
m
0
and h, in each patch thus affecting the growth of cosmological perturbations at recent times. Hence, if our local patch of the universe (with uniform vacuum density) is big enough — which is likely to happen given that we should have on average about one domain per horizon volume — we might not notice these large-scale inhomogeneities. This happens because in order to see a patch with a different vacuum density one may have to look back at a time when the universe was still very homogeneous.
A mesoscopic kinetic model for phase separation in the presence of liquid crystalline order has been formulated and solved using high performance numerical methods. The thermodynamic phase diagram on ...temperature-polymer concentration plane indicates the presence of coexistence regions between isotropic and liquid crystalline phases. These regions are partitioned by the phase-separation spinodal and the phase-ordering spinodal. We characterize the morphologies following temperature quenches in the phase diagram. The scenario is completely different from isotropic mixing since the continuous phase exhibits liquid crystalline ordering. Microdomains of the dispersed phase induce long- and short-range forces affecting the kinetics of the phase separation and the emerging structures. Presence of topological defects and elastic distortions around the microdomains formed during the phase separation dominate the morphology. The free energy of the system establishes dynamics and correlations of the morphological structures.
Coupled Ginzburg–Landau equations appear in a variety of contexts involving instabilities in oscillatory media. When the relevant unstable mode is of vectorial character (a common situation in ...nonlinear optics), the pair of coupled equations has special symmetries and can be written as a
vector complex Ginzburg-Landau (CGL)
equation. Dynamical properties of localized structures of topological character in this vector-field case are considered. Creation and annihilation processes of different kinds of vector defects are described, and some of them interpreted in theoretical terms. A transition between different regimes of spatiotemporal dynamics is described.
Nonlinear properties of ionization instability in an argon glow discharge are demonstrated experimentally and numerically. Dislocation-like topological defects indicate strong nonlinearity which ...desynchronizes the wave of stratification. The evolution of a defect sensitively depends on striation amplitude and leads to spatio-temporal chaos. In a chaotic state movement of striations is interrupted by evolution of defects and resembles a directed stochastic motion of colliding, annihilating and creating particles.
We consider classical solutions for strings ending on magnetically charged black holes in four-dimensional Kaluza–Klein theory. We examine the classical superstring and the global vortex, which can ...be viewed as a nonsingular model for the superstring. We show how both of these can end on a Kaluza–Klein monopole in the absence of self-gravity. Including gravitational back-reaction gives rise to a confinement mechanism of the magnetic flux of the black hole along the direction of the string. We discuss the relation of this work to localized solutions in ten-dimensional supergravity.
For the description of the long‐wavelength quantum states of electrons in crystals with topological defects we establish a general framework on the basis of the continuum theory of defects. The ...resulting one‐particle Schrödinger equation lives on a Riemann‐Cartan manifold, representing the distorted crystal, and consists of two parts. All effects due to the topology of the defects are contained in the first part which has a covariant form and describes the purely geometric particle motion. The second part is non‐covariant and derives from deformation‐dependent tunneling rates of the particle which e.g. are responsible for the existence of bound states to edge dislocations.
The screw-dislocation line energy density
E
SD in a vortex lattice (VL) was numerically computed on the basis of the isotropic London approximation. The computation premised that the slip planes are ...spaced
D
SP apart with the Burgers vectors of two adjacent slip planes being antiparallel. The results of the computation give a practical approximate expression for
E
SD. This expression is valid for vortex-lattice-tilt deformations much less than
a
0/
λ, where
a
0 is the vortex-lattice constant and
λ is the London penetration depth. The approximate expression for
E
SD was applied to the Larkin–Ovchinnikov pinning theory, and stability of screw dislocations in a pinned VL was investigated for the case where the ratio 5
λ/
a
0 ranges around the Ginzburg–Landau parameter. Screw dislocations of high densities (
D
SP∼
a
0) are expected to be stable for sufficiently strong pinning, but screw dislocations of low densities (
D
SP≫
a
0) are always merely metastable. These results provided a probable criterion such that no screw dislocations destruct Bragg-glass order. Within a framework of the present theoretical description, screw-dislocation-induced plasticization is not responsible for discrepancy between the Larkin–Ovchinnikov pinning theory and experiments in bulks (three-dimensional vortex systems).
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