Decay of Excited D-branes
Akikazu Hashimoto, Igor R. Klebanov
TL;DR
Hashimoto and Klebanov analyze leading-order interactions of massless D-brane excitations, showing that D-brane NS sector four-point amplitudes reproduce known Type I results. They derive the leading three-point amplitude for two open-string states decaying to a massless closed string, $A = \frac{\Gamma(-2 t)}{\Gamma(1-t)^2} K(1,2,3)$, with a single invariant $t$ and demonstrate an exponential decay $A \sim 2^{-2 t} t^{-3/2}$ at large $t$, signaling brane smearing at high energies. The work extends to disk amplitudes with one bulk and two boundary vertices, revealing consistent Type I kinematic factors across sectors and highlighting the role of poles from massive open-string exchanges. It concludes that the high-energy, smeared D-brane halo governs the dominant Hawking-radiation channel for non-extremal D-branes, informing non-perturbative D-brane dynamics and open–closed string interactions.
Abstract
We calculate the leading order interactions of massless D-brane excitations. Their 4-point functions are found to be identical to those found in type I theory. The amplitude for two massless D-brane fluctuations to produce a massless closed string is found to possess interesting new structure. As a function of its single kinematic invariant, it displays an infinite sequence of alternating zeros and poles. At high transverse momenta, this amplitude decays exponentially, indicating a growing effective thickness of the D-brane. This amplitude is the leading process by which non-extremal D-branes produce Hawking radiation.