Non-threshold (F, Dp) bound states

TL;DR

This paper explicitly constructs BPS bound states of Dp branes with electric fields using T-duality, confirms their properties match previous worldvolume results, and explores their implications for the AdS/CFT correspondence.

Contribution

It provides explicit constructions of (F, Dp) bound states for 2 ≤ p ≤ 7 via T-duality, confirming previous theoretical predictions and analyzing their decoupling limits.

Findings

Bound states preserve half of the supersymmetry.

Charge and tension calculations match previous worldvolume results.

Effective string coupling can be quantized and independent of the usual string coupling.

Abstract

In the previous paper [hep-th/9904112], we argued that there exist BPS bound states of Dp branes carrying certain units of quantized constant electric field for every $p$ (with $1 \le p \le 8$). Each of these bound states preserves one half of the spacetime supersymmetries. In this paper, we construct these bound state configurations explicitly for $2 \le p \le 7$ from Schwarz's $(m,n)$-string or (F, D1) bound state in type IIB string theory by T-dualities along the transverse directions. We calculate the charge per $(2\pi)^{p -1} \alpha'^{(p - 1)/2}$ of $(p -1)$-dimensional area for F-strings in (F, Dp) and the tension for each of these bound states. The results agree precisely with those obtained previously from the worldvolume study. We study the decoupling limit for the (F, D3) bound state and find that Maldacena's $AdS_5/CFT_4$ correspondence may hold true even with respect to thisbound state but now with an effective string coupling rather than the usual string coupling. This coupling is quantized and can be independent of the usual string coupling in certain limit.