Birefringent Electroweak Textures

The behaviour of electromagnetic waves propagating through an electroweak homilia string network is examined. This string network is topologically stable as a cosmic texture, and is characterized by the spatial variation of the isospin rotation of the Higgs field. As a consequence the photon field couples to the intermediate vector bosons, producing a finite range electromagnetic field. It is found that the propagation speed of the photon depends on its polarization vector, whence an homilia string network acts as a birefringent medium. We estimate the birefringent scale for this texture and show that it depends on the frequency of the electromagnetic wave and the length scale of the homilia string network.Comment: 10 page

Reply to "Comment on 'Gravitating Magnetic Monopole in the Global Monopole Spacetime' "

In this Reply I present some arguments in favor of the stability of the topological defect composed by global and magnetic monopoles.Comment: 1 page, no figures. Revised version improves the theoretical analysis about electrostatic self-interaction in the global monopole spacetim

O(4) texture with a cosmological constant

We investigate O(4) textures in a background with a positive cosmological constant. We find static solutions which co-move with the expanding background. There exists a solution in which the scalar field is regular at the horizon. This solution has a noninteger winding number smaller than one. There also exist solutions in which scalar-field derivatives are singular at the horizon. Such solutions can complete one winding within the horizon. If the winding number is larger than some critical value, static solutions including the regular one are unstable under perturbations.Comment: 25 pages, revtex, 6 eps figure

Is baryon number violated when electroweak strings intercommute?

We reexamine the self-helicity and the intercommutation of electroweak strings. A plausible argument for baryon number conservation when electroweak strings intercommute is presented. The connection between a segment of electroweak strings and a sphaleron is also discussed.Comment: CALT-68-1948, 11 pages, 5 figures available upon request. Replaced with revised version. (Request should be sent to [email protected]

Z-Vortex Percolation in the Electroweak Crossover Region

We study the statistical properties of Z-vortices and Nambu monopoles in the 3D SU(2) Higgs model for a Higgs mass M_H \approx 100 GeV near and above the crossover temperature, where these defects are thermally excited. Although there is no phase transition at that strong selfcoupling, we observe that the Z-vortices exhibit the percolation transition that has been found recently to accompany the first order thermal transition that exists at smaller Higgs mass. Above the crossover temperature percolating networks of Z-vortex lines are ubiquitous, whereas vortices form a dilute gas of closed vortex loops and (Nambu) monopolium states on the low-temperature side of the crossover. The percolation temperature turns out to be roughly independent of the lattice spacing. We find that the Higgs modulus is smaller (the gauge action is larger) inside the vortices, compared to the bulk average. This correlation becomes very strong on the low-temperature side. The percolation transition is a prerequisite of some string mediated baryon number generation scenarios.Comment: 16 pages, LaTeX, 12 figures, epsf.sty needed; final version to appear in Phys. Lett.

Embedded Vortices

We present a discussion of embedded vortices in general Yang-Mills theories. The origin of a family structure of solutions is shown to be group theoretic in nature and a procedure for its determination is developed. Vortex stability can be quantified into three types: Abelian topological stability, non-Abelian topological stability, and dynamical stability; we relate these to the family structure of vortices, in particular discussing how Abelian topological and dynamical stability are related. The formalism generally encompasses embedded domain walls and embedded monopoles also.Comment: final corrections. latex fil

Collapse of topological texture

We study analytically the process of a topological texture collapse in the approximation of a scaling ansatz in the nonlinear sigma-model. In this approximation we show that in flat space-time topological texture eventually collapses while in the case of spatially flat expanding universe its fate depends on the rate of expansion. If the universe is inflationary, then there is a possibility that texture will expand eternally; in the case of exponential inflation the texture may also shrink or expand eternally to a finite limiting size, although this behavior is degenerate. In the case of power law noninflationary expansion topological texture eventually collapses. In a cold matter dominated universe we find that texture which is formed comoving with the universe expansion starts collapsing when its spatial size becomes comparable to the Hubble size, which result is in agreement with the previous considerations. In the nonlinear sigma-model approximation we consider also the final stage of the collapsing ellipsoidal topological texture. We show that during collapse of such a texture at least two of its principal dimensions shrink to zero in a similar way, so that their ratio remains finite. The third dimension may remain finite (collapse of cigar type), or it may also shrink to zero similar to the other two dimensions (collapse of scaling type), or shrink to zero similar to the product of the remaining two dimensions (collapse of pancake type).Comment: 23 pages, LaTeX, to be published in Phys. Rev.

Embedded Topological Defects in Hot Electroweak Theory: a Lattice Study

We study the properties of Nambu monopoles and Z-vortices in the 3D lattice SU(2) Higgs theory which represents the Standard Model at high temperature. We show that the densities of the Nambu monopoles and the Z-vortices are O(1) in the symmetric phase and generically small in the Higgs phase. Near to the critical Higgs mass and in the vicinity of the phase transition the densities are no more negligible in the broken phase. The percolation probability of the Z-vortex lines is found as a new disorder parameter for this phase transition. We conclude that the transition to the symmetric phase is accompanied by Z-vortex condensation. Simulations comparing elementary and extended vortices and monopoles at different \beta_G values, aiming to show that the density of vortices and monopoles of fixed physical size might have a well-defined continuum limit, gives encouraging but so far inconclusive results.Comment: 13 pages, LaTeX, 8 figures, epsf.sty needed; revision: minor changes and reference adde

Textures and Newtonian Gravity

Newtonian theory is used to study the gravitational effects of a texture, in particular the formation of massive structures.Comment: 4 pages, 4 ps figures, REVTEX, accepted for publication in PR