Localized Tachyons and RG Flows

TL;DR

This paper investigates how localized closed string tachyon condensation affects the energy density and related quantities in non-supersymmetric orbifold backgrounds, revealing decreases in effective central charge and boundary entropy during RG flows.

Contribution

It introduces a detailed analysis of localized tachyon condensation on defects, connecting geometric resolutions with RG flow properties and entropy measures in non-supersymmetric orbifolds.

Findings

Tachyon condensation decreases effective central charge in some cases.

In certain flows, the boundary entropy g_{cl} decreases, indicating a loss of degrees of freedom.

Non-singular orbifolds are related to singular ones via tachyon condensation, with g_{cl} decreasing along these flows.

Abstract

We study condensation of closed string tachyons living on defects, such as orbifold fixed planes and Neveu-Schwarz fivebranes. We argue that the high energy density of localized states decreases in the process of condensation of such tachyons. In some cases this means that $c_{eff}$ decreases along the flow; in others, $c_{eff}$ remains constant and the decreasing quantity is a closed string analog, $g_{cl}$, of the ``boundary entropy'' of D-branes. We discuss the non-supersymmetric orbifolds $C/Z_n$ and $C^2/Z_n$. In the first case tachyon condensation decreases $n$ and in some cases connects type II and type 0 vacua. In the second case non-singular orbifolds are related by tachyon condensation to both singular and non-singular ones. We verify that $g_{cl}$ decreases in flows between non-singular orbifolds. The main tools in the analysis are the structure of the chiral ring of the perturbed theory, the geometry of the resolved orbifold singularities, and the throat description of singular conformal field theories.