Birth of Closed Strings and Death of Open Strings During Tachyon Condensation

Abstract

The tremendous progress achieved through the study of black holes and branes suggests that their time dependent generalizations called Spacelike branes (S-branes) may prove similarly useful. An example of an established approach to S-branes is to include a string boundary interaction and we first summarize evidence for the death of open string degrees of freedom for the homogeneous rolling tachyon on a decaying brane. Then, we review how to extract the flat S-brane worldvolumes describing the homogeneous rolling tachyon and how large deformations correspond to creation of lower dimensional strings and branes. These S-brane worldvolumes are governed by S-brane actions which are on equal footing to D-brane actions, since they are derived by imposing conformality on the string worldsheet, as well as by analyzing fluctuations of time dependent tachyon configurations. As further examples we generalize previous solutions of the S-brane actions so as to describe multiple decaying and nucleating closed fundamental strings. Conceptually Sbrane actions are therefore different from D-brane actions and can provide a description of time dependent strings/branes and possibly their interactions.

Aspects of Dirichlet S-branes

“…At this point, as it will become clear in the T-dual picture discussed below, open strings become massless, and the Born-Infeld action cannot be trusted any longer, A natural conjecture is that the S-brane world-volume becomes time-like and describes a shower of D-brane and anti-D-branes. This is consistent with the analysis in [11], where solutions of the S-brane action (3) including the magnetic field were interpreted as the formation or annihilation of D-branes or strings.…”

“…The curve cannot be distinguished from its approximation (28) (in black), but misses the oscillations. Right: a zoom on the interval ∆ ∈ [10,11] clearly shows the oscillations. We have set p = 2 and α ′ = 1/(2π) for both plots.…”

Brane with transverse rotation and background fields: boundary state and tachyon condensation

“…The fate of an unstable D-brane can be investigated via the dynamics of the open string tachyon, i.e., the tachyon condensation process [3]. An unstable D-brane usually decays to another lower dimensional unstable D-brane as an intermediate state [4,5,6]. This intercurrent state eventually collapses to the closed string vacuum or decays to a lower dimensional stable configuration.…”

Algebraic form of the M3-brane action

“…Two examples of unstable states in superstring theories are: non-BPS branes (odd (even) dimensional branes in type IIA (IIB) theory) and brane-anti-brane pairs in both type IIA and IIB theories [20,21]. One of the interesting facts about the dynamics of these unstable branes, generally obvious in effective action formulation, is their dimensional reduction through tachyon condensation [22][23][24][25][26][27]. During this process the negative energy density of the tachyon potential at its minimum point, cancels the tension of the D-brane (or D-branes) [28], and the final product is a closed string vacuum without a D-brane or stable lower dimensional D-branes.…”