The production, spectrum and evolution of cosmic strings in brane inflation

Abstract

Brane inflation in superstring theory predicts that cosmic strings (but not domain walls or monopoles) are produced towards the end of the inflationary epoch. Here, we discuss the production, the spectrum and the evolution of such cosmic strings, properties that differentiate them from those coming from an abelian Higgs model. As D-branes in extra dimensions, some type of cosmic strings will dissolve rapidly in spacetime, while the stable ones appear with a spectrum of cosmic string tensions. Moreover, the presence of the extra dimensions reduces the interaction rate of the cosmic strings in some scenarios, resulting in an order of magnitude enhancement of the number/energy density of the cosmic string network when compared to the field theory case.

Inflation and String Theory

“…The intercommutation probabilities of cosmic F-strings and D-strings can be much smaller than those for field theory cosmic strings, as carefully examined in [602]. In particular, a colliding pair of strings can miss each other in the compact dimensions [597,600,602], and the string coupling g s also suppresses the intercommutation probability. Perhaps the most compelling setting for cosmic superstring production is warped D-brane inflation [41], in which annihilation of a D3-brane/anti-D3-brane pair via condensation of a complex tachyon automatically produces a collection of cosmic strings, and warping provides a natural parametric mechanism through which the tension can be small enough to obey observational bounds.…”

“…A renewed study of cosmic superstrings was initiated by Tye and collaborators in [595][596][597]. The essential new insight was that if the Standard Model arises on D-branes, the visible sector couplings and the string tension in Planck units can be adjusted independently, by changing the string 23 Most searches for cosmic string lensing involve extragalactic objects (cf.…”

Exact wave propagation in a spacetime with a cosmic string

“…The time of flight along the trajectory BP is obtained by just replacing ϕ with −ϕ. Hence, substituting (27) into (25), we find that the waveform in the geometrical optics is the same as Eq. (24) except for an overall phase e iroξ .…”

“…In this scenario inflation is driven by the attractive force between parallel Dbranes and parallel anti D-branes in a higher dimensional spacetime. When those brane-anti-brane pairs collide and annihilate at the end of inflation, lower-dimensional D-branes, which behave like monopoles, cosmic strings or domain walls from the view point of four-dimensional observers, are formed generically [25,26,27,28,29].…”

Reconnection of non-abelian cosmic strings

“…Similarly, D-strings may also pass through each other, reconnecting with probability P < 1 [16,17]. A reduced probability for reconnection affects the scaling solution for the string network, resulting in a larger concentration of strings in the sky [18,19,2]. Given enough data, it is not implausible that one could extract the probability P from observation.…”