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Remarks on brane and antibrane dynamics

Ben Michel, Eric Mintun, Joseph Polchinski, Andrea Puhm, Philip Saad

TL;DR

The paper argues that brane actions should be embedded in an effective field theory to properly treat divergences and to connect with UV physics. It illustrates this with a simple toy model and then applies the EFT framework to antibranes in flux backgrounds, particularly a single anti-D3 in KKLT/KS setups, showing no zero-temperature tachyon and that the brane is screened by flux but cannot annihilate with its screening cloud due to the $H_3$ Bianchi identity; the primary nonperturbative decay channel remains the NS5-brane instanton. For multiple antibranes, the authors discuss non-Abelian dynamics and polarization effects, outlining conditions under which branes may be expelled or stabilized, while preserving metastability for modest brane numbers. Overall, EFT provides a consistent, controlled description of brane–flux systems and supports the viability of metastable antibrane constructions in string phenomenology.

Abstract

We develop the point of view that brane actions should be understood in the context of effective field theory, and that this is the correct way to treat classical as well as loop divergences. We illustrate this idea in a simple model. We then consider the implications for the dynamics of antibranes in flux backgrounds, focusing on the simplest case of a single antibrane. We argue that there is no tachyonic instability at zero temperature, but there is a nonperturbative process in which an antibrane annihilates with its screening cloud. This is distinct from the NS5-brane instanton decay. Constraints on models of metastable supersymmetry breaking by antibranes may be tightened, but there is no problem of principle with this mechanism.

Remarks on brane and antibrane dynamics

TL;DR

The paper argues that brane actions should be embedded in an effective field theory to properly treat divergences and to connect with UV physics. It illustrates this with a simple toy model and then applies the EFT framework to antibranes in flux backgrounds, particularly a single anti-D3 in KKLT/KS setups, showing no zero-temperature tachyon and that the brane is screened by flux but cannot annihilate with its screening cloud due to the Bianchi identity; the primary nonperturbative decay channel remains the NS5-brane instanton. For multiple antibranes, the authors discuss non-Abelian dynamics and polarization effects, outlining conditions under which branes may be expelled or stabilized, while preserving metastability for modest brane numbers. Overall, EFT provides a consistent, controlled description of brane–flux systems and supports the viability of metastable antibrane constructions in string phenomenology.

Abstract

We develop the point of view that brane actions should be understood in the context of effective field theory, and that this is the correct way to treat classical as well as loop divergences. We illustrate this idea in a simple model. We then consider the implications for the dynamics of antibranes in flux backgrounds, focusing on the simplest case of a single antibrane. We argue that there is no tachyonic instability at zero temperature, but there is a nonperturbative process in which an antibrane annihilates with its screening cloud. This is distinct from the NS5-brane instanton decay. Constraints on models of metastable supersymmetry breaking by antibranes may be tightened, but there is no problem of principle with this mechanism.

Paper Structure

This paper contains 7 sections, 33 equations, 3 figures.

Table of Contents

  1. Introduction
  2. Effective brane actions
  3. Antibranes in fluxes
  4. Application of EFT
  5. More on antibrane dynamics
  6. Multiple antibranes
  7. Conclusions

Figures (3)

  • Figure 1: First, second, and third order terms in the amplitude for $\phi$ to scatter from the brane.
  • Figure 2: a) Lowest order backreaction on $H_3$. The heavy line is the anti-D3 brane, and the $\times$ denotes a background field. b) Corresponding contribution to the brane potential.
  • Figure 3: D6 densities in a flux background. In all cases the excess or deficit in the screening cloud offsets that due to the brane source. a) D6-brane in a flux background. b) Anti-D6-brane in a flux background. c) Fluctuation of the anti-D6-brane's screening cloud down to a size of order the string length.