String Network

Type IIB string theory admits a BPS configuration in which three strings (of different type) meet at a point. Using this three string configuration we construct a string network and study its properties. In particular we prove supersymmetry of this configuration. We also consider string lattices, which can be used to construct BPS states in toroidally compactified string theory.Comment: LaTeX file, 8 pages, 3 figures, reference adde

A Word String Network

Logologists have been aware of word strings -- overlapping lists of words such as sat, ate, tea, ear, are -- since at least the time of the great English puzzle-constructor Henry Ernest Dudeney. However, no one seems to have realized that word strings can be diagrammed in a network, much as has been done for word ladders (see, for example, the May and August 1973 issue of Word Ways, or Chapter 4 of my book Word Recreations, published by Dover in 1979)

String Network and U-Duality

We discuss the generalization of recently discovered BPS configurations, corresponding to the planar string networks, to non-planar ones by considering the U-duality symmetry of type II string theory in various dimensions. As an explicit example, we analyze the string solutions in 8-dimensional space-time, carrying SL(3) charges, and show that by aligning the strings along various directions appropriately, one can obtain a string network which preserves 1/8 supersymmetry.Comment: 8 pages, latex, references added, minor modification

String Network from M-theory

We study the three string junctions and string networks in Type IIB string theory by explicity constructing the holomorphic embeddings of the M-theory membrane that describe such configurations. The main feature of them such as supersymmetry, charge conservation and balance of tensions are derived in a more unified manner. We calculate the energy of the string junction and show that there is no binding energy associated with the junction.Comment: 16 pages, harvmac, 2 figures, references adde

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

Cosmic string loops and large-scale structure

We investigate the contribution made by small loops from a cosmic string network as seeds for large-scale structure formation. We show that cosmic string loops are highly correlated with the long-string network on large scales and therefore contribute significantly to the power spectrum of density perturbations if the average loop lifetime is comparable to or above one Hubble time. This effect further improves the large-scale bias problem previously identified in earlier studies of cosmic string models.Comment: 5 pages, 5 figure

Cosmological evolution of cosmic strings with time-dependent tension

We discuss the cosmological evolution of cosmic strings with time-dependent tension. We show that, in the case that the tension changes as a power of time, the cosmic string network obeys the scaling solution: the characteristic scale of the string network grows with the time. But due to the time dependence of the tension, the ratio of the energy density of infinite strings to that of the background universe is {\it not} necessarily constant.Comment: 9 pages, to appear in Phys. Rev.

Low-energy propagation modes on string network

We study low-energy propagation modes on string network lattice. Specifically, we consider an infinite two-dimensional regular hexagonal string network and analyze the low frequency propagation modes on it. The fluctuation modes tangent to the two-dimensional plane respect the spatial rotational symmetry on the plane, and are described by Maxwell theory. The gauge symmetry comes from the marginal deformation of changing the sizes of the loops of the lattice. The effective Lorentz symmetry respected at low energy will be violated at high energy.Comment: LaTeX, 10 pages, 3 figures, a wrong factor correcte