D-instantons and closed string tachyons in Misner space

Abstract

We investigate closed string tachyon condensation in Misner space, a toy model for big bang universe. In Misner space, we are able to condense tachyonic modes of closed strings in the twisted sectors, which is supposed to remove the big bang singularity. In order to examine this, we utilize D-instanton as a probe. First, we study general properties of D-instanton by constructing boundary state and effective action. Then, resorting to these, we are able to show that tachyon condensation actually deforms the geometry such that the singularity becomes milder. *

AdS bubbles, entropy and closed string tachyons

“…A simple example of the bulk tachyon condensation in bosonic string (or type 0 string) has been proposed to be described by the time-like Liouville theory [25] [26] (see e.g. [27][28][29] [24][30] [31][5] [32] for a partial list of further progresses). However, this theory has not been completely understood, especially because the continuation from the Euclidean theory is not straightforward; there is a potential ambiguity with respect to the choice of vacua in a time-dependent background.…”

Time-dependent cosmologies and their duals

“…Some previous attempts at studying time dependent phenomena pertaining to cosmological singularities in string theory include e.g. [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31].…”

Big bang models in string theory

“…This technique has also been used for the variation of the Milne orbifold with localized closed string tachyons. However, the analysis is subtle and two groups arrive at contradictory conclusions as to whether the big bang region is connected to a big crunch region after tachyon condensation [47,48]. …”