Cosmic Strings and Cosmic Superstrings

Abstract

In these lectures, I review the current status of cosmic strings and cosmic superstrings. I first discuss topological defects in the context of Grand Unified Theories, focusing in particular in cosmic strings arising as gauge theory solitons. I discuss the reconciliation between cosmic strings and cosmological inflation, I review cosmic string dynamics, cosmic string thermodynamics and cosmic string gravity, which leads to a number of interesting observational signatures. I then proceed with the notion of cosmic superstrings arising at the end of brane inflation, within the context of brane-world cosmological models inspired from string theory. I discuss the differences between cosmic superstrings and their solitonic analogues, I review our current understanding about the evolution of cosmic superstring networks, and I then briefly describe the variety of observational consequences, which may help us to get an insight into the stringy description of our Universe.

Effect of kinematic constraints on multitension string network evolution

“…In the first step, one solves the system with initial guess values assigned to " v ij 's, and then solves the system again, replacing the initial guesses for " v ij 's with the corresponding values obtained by inserting the returned scaling values of v i ðtÞ's into Eq. (17) . Repeating this procedure (in practice two or three iterations are needed), one can match the input " v ij 's to those obtained at scaling, to the required accuracy.…”

“…The interest in the results of these simulations wained when it became evident that cosmic strings by themselves were never going to provide the seed primordial density fluctuations [10], but recently interest in them has resurfaced thanks to the realization that in a reasonably large class of superstring motivated models, it is possible to form a network of strings [11][12][13][14], that can live as long as the age of the Universe, be of cosmological length, and survive a period of early Universe inflation. Moreover, these cosmic superstrings could possibly be detected, thereby providing the first direct evidence of string theory in nature (for recent reviews of cosmic superstrings see [15][16][17][18][19]). This has spawned a renewed interest in the subject; in particular, there is now a need to understand how a network of cosmic superstrings evolves.…”

Cosmic strings and superstrings

“…Indeed, it is now very possible that observations of a cosmic superstring might provide the first real direct evidence for M-theory. (For reviews see Polchinski 2005;Davis & Kibble 2005;Myers & Wyman 2009;Sakellariadou 2009. ) We begin, in §2, by describing the simplest examples of cosmic strings, which arise in the breaking of an abelian U (1) symmetry, and discuss the reasons for thinking that cosmic strings might appear during phase transitions in the very early history of the universe, in a process closely analogous to what happens when a superfluid or superconductor is cooled rapidly through its transition temperature.…”

Self-dual configurations in Abelian Higgs models with k-generalized gauge field dynamics

“…Another interesting scenario for to study Maxwell-Higgs models is related to cosmic strings, topological defects similar to the vortices, which may have great importance in the evolution of the Cosmos and formation of the structures existing in the Universe [44][45][46][47][48]. The community has renewed its interest because recently it was established that superstrings theory supports cosmic strings solutions inside its theoretical framework [49].…”