Electromagnetic Duality and D3-Brane Scattering Amplitudes Beyond Leading Order

TL;DR

This paper investigates electromagnetic duality and scattering amplitudes of D3-branes beyond leading order using on-shell methods, revealing new duality invariances, loop-level double-copy structures, and the role of counterterms in restoring duality.

Contribution

It introduces a novel on-shell recursion approach to demonstrate duality invariance and computes explicit loop-level amplitudes, highlighting tensions between duality and color-kinematics duality.

Findings

Derived duality invariance of Born-Infeld electrodynamics via on-shell methods.

First explicit loop-level BCJ double-copy in a non-gravitational model.

Explicit all-multiplicity 1-loop integrand for $ ext{N}=4$ DBI.

Abstract

We use on-shell methods to study the non-supersymmetric and supersymmetric low-energy S-matrix on a probe D3-brane, including both the 1-loop contributions of massless states as well as the effects of higher-derivative operators. Our results include: (1) A derivation of the duality invariance of Born-Infeld electrodynamics as the dimensional oxidation of the group of spatial rotations transverse to a probe M2-brane; this is done using a novel implementation of subtracted on-shell recursion. (2) The first explicit loop-level BCJ double-copy in a non-gravitational model, namely the calculation of the 4-point self-dual amplitude of non-supersymmetric Born-Infeld. (3) From previous results for $n$-point self-dual 1-loop BI amplitudes and the conjectured dimension-shifting relations in Yang-Mills, we obtain an explicit all-multiplicity, at all orders in $\epsilon$, expression for the 1-loop integrand of the MHV sector of $\mathcal{N}=4$ DBI. (4) For all $n>4$, the explicitly integrated duality-violating 1-loop amplitudes (self-dual and next-to-self-dual in pure BI as well as MHV in $\mathcal{N}=4$ DBI) are shown to be removable at $\mathcal{O}(\epsilon^0)$ by adding finite local counterterms; we propose that this may be true more generally at 1-loop order. (5) We find that in non-supersymmetric Born-Infeld, not all finite local counterterms needed to restore electromagnetic duality can be constructed using the double-copy with higher-derivative corrections, suggesting a fundamental tension between electromagnetic duality and color-kinematics duality at loop-level. Finally we comment on oxidation of duality symmetries in supergravity and the parallels it has to the M2-brane to D3-brane oxidation demonstrated in this paper.