Closed String Tachyons and Their Implications for Non-Supersymmetric Strings

Abstract

Closed string tachyons have long been somewhat mysterious. We note that there is often a regime in the classical moduli space in which one can systematically compute the effective action for such fields. In this regime, the tachyon is light, and cannot be integrated out. Instead, one must consider the combined dynamics of gravitons, moduli, tachyons and other light fields. We compute the action and find that the quartic term for the tachyon is positive in the field definition where the tachyon has no derivative coupling to the radion. We study the evolution of isotropic, homogeneous configurations and find that typically the system is driven to regions where the calculation is no longer under control.

On closed string tachyon dynamics

“…If the tachyon mixes with marginal or nearly marginal operators such as additional graviton or dilaton modes (which will appear in our formalism as operators of the form O a and O a R (2) ), these modes can become large. This can be seen, for example, in [37]. On the other hand, as long as V and ∂ b V remain small, the derivative expansion is still a good one.…”

Closed string tachyon condensation: an overview

“…See [119,120,121,122,123,124,125,126,127,128,129,130,131] for other investigations of bulk tachyon condensation.…”

Numerical simulation of the quasi-resonance regime of a transient double resonance in a scheme with a common upper level at a large inhomogeneous broadening of quantum transitions

“…For example, if the tachyon potential includes a positive quartic term [27], there will be a solution of slightly lower action with a small admixture of the unstable mode.…”