Dirac-Born-Infeld actions and Tachyon Monopoles

TL;DR

This paper explores magnetic monopole solutions in the non-abelian Dirac-Born-Infeld action for coincident non-BPS D9-branes, revealing their relation to BPS D6-branes and analyzing regularization and fluctuation properties.

Contribution

It introduces a regularized monopole ansatz in the non-abelian DBI framework and connects monopole solutions to BPS D6-branes, including tension calculations and trace prescription implications.

Findings

Monopole solutions are singular and require regularization.

Fluctuations describe a BPS D6-brane of codimension 3.

Derived a tension formula for the D6-brane.

Abstract

We investigate magnetic monopole solutions of the non-abelian DBI action describing 2 coincident non-BPS D9-branes in flat space. Just as in the case of kink and vortex solitonic tachyon solutions of the full DBI non-BPS actions, as previously analyzed by Sen, these monopole configurations are singular in the first instance and require regularization. We discuss a suitable non-abelian ansatz and show it solves the equations of motion to leading order in the regularization parameter. Fluctuations are studied and shown to describe a codimension 3 BPS D6-brane. A formula is derived for its tension. We comment on the implication to our results from both the trace (Tr) and symmetrized trace (Str) prescriptions of the non-abelian DBI action of coincident non-BPS D9-branes.