Inflation from D-\bar{D} brane annihilation

TL;DR

The paper presents a string-theoretic inflation mechanism where the annihilation of a $D5$-$\bar{D}5$ pair creates a co-dimension-two vortex on a resulting $D3$-brane, whose false vacuum energy drives inflation on our 3+1D spacetime. By invoking Sen’s tachyon condensation and defect-driven (topological) inflation, the authors formulate a 6D gravitational action with a tachyon vortex, derive a time-dependent vortex solution, and demonstrate inflation on the brane along with possible transverse expansion. Inflation ends naturally as the vortex acquires bulk motion and unwinds the tachyon, reducing the localized vacuum energy while potentially seeding localized matter through vortex dynamics and cusps/vortons. The work connects to broader themes in string cosmology, including topological inflation and Brandenberger–Vafa-type ideas, and highlights open questions about the uniqueness of the inflating hypersurface and the precise mechanism of matter localization. Overall, it offers a dynamical, topological pathway to implement inflation within a string-theoretic framework with a natural end and matter localization prospects.

Abstract

We demonstrate that the initial conditions for inflation are met when D5 and \bar{D}5 branes annihilate. This scenario uses Sen's conjecture that a co-dimension two vortex forms on the worldvolume of the annihilated 5-brane system. Analogous to a "Big Bang", when the five branes annihilate, a vortex localized on a 3-brane forms and its false vacuum energy generates an inflationy space-time. We also provide a natural mechanism for ending inflation via the motion of the vortex in the bulk due to its extrinsic curvature. We also suggest a consistent way to end inflation and localize matter on our space-time.

Figures (2)

• Figure 1: This is a depiction of the annihilation of the $D5-\bar{D}5$ brane system, represented as a two dimensional surface. A vortex, represented as a line, forms after the D5 branes annhihlate. In our mechanism, this vortex initiates an inflating 3+1D hypersurface.
• Figure 2: The vortex has extrinsic curvature and will move away from the initial inflating hypersurface it was created on. This causes the tachyon field to roll down the false vacuum potential eventually ending inflation on the hypersurface $\cal{M}\rm_{4}$