Solitonic D-branes and brane annihilation

TL;DR

This paper explores analogies between field theory solitons and D-branes, focusing on brane annihilation, flux tube formation, and energy transfer to closed string states, with implications for early universe cosmology.

Contribution

It introduces a novel analogy between soliton dynamics and D-brane behavior, especially in brane annihilation and flux tube formation, providing new insights into string theory and cosmological defect production.

Findings

Annihilating soliton-antisoliton pairs can produce lower-dimensional stable solitons.

Localization of gauge fields implies open flux tubes ending on solitons.

Energy from brane annihilation is carried away by closed string excitations.

Abstract

We point out some intriguing analogies between field theoretic solitons (topological defects) and D-branes. Annihilating soliton-antisoliton pairs can produce stable solitons of lower dimensionality. Solitons that localize massless gauge fields in their world volume automatically imply the existence of open flux tubes ending on them and closed flux tubes propagating in the bulk. We discuss some aspects of this localization on explicit examples of unstable wall-anti-wall systems. The annihilation of these walls can be described in terms of tachyon condensation which renders the world-volume gauge field non-dynamical. During this condensation the world volume gauge fields (open string states) are resonantly excited. These can later decay into closed strings, or get squeezed into a network flux tubes similar to a network of cosmic strings formed at a cosmological phase transition. Although, as in the $D$-brane case, perturbatively one can find exact time-dependent solutions, when the energy of the system stays localized in the plane of the original soliton, such solutions are unstable with respect to decay into open and closed string states. Thus, when a pair of such walls annihilates, the energy is carried away (at least) by closed string excitations (``glueballs''), which are the lowest energy excitations about the bulk vacuum. Suggested analogies can be useful for the understanding of the complicated D-brane dynamics and of the production of topological defects and reheating during brane collision in the early universe.