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41
Closed String Tachyon Condensation: An Overview
, 2005
"... These notes are an expanded version of a review lecture on closed string tachyon condensation at the RTN workshop in Copenhagen in September 2003. We begin with a lightning review of open string tachyon condensation, and then proceed to review recent results on localized closed string tachyon conden ..."
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Cited by 59 (6 self)
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These notes are an expanded version of a review lecture on closed string tachyon condensation at the RTN workshop in Copenhagen in September 2003. We begin with a lightning review of open string tachyon condensation, and then proceed to review recent results on localized closed string tachyon condensation, focusing on two simple systems, C/Zn orbifolds and twisted circle compactifications.
Evolution of Dbranes under closed string tachyon condensation
"... We study the evolution of stable Dbranes of C/Z n and twisted circle theories in the process of closed string tachyon condensation. We interpret the fractional branes in these backgrounds as type II branes wrapping (‘blown up’) cycles, and trace the evolution of the corresponding cycles under tachy ..."
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Cited by 21 (2 self)
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We study the evolution of stable Dbranes of C/Z n and twisted circle theories in the process of closed string tachyon condensation. We interpret the fractional branes in these backgrounds as type II branes wrapping (‘blown up’) cycles, and trace the evolution of the corresponding cycles under tachyon condensation. We also study RG flows of the corresponding N = 2 boundary conformal field theories. We find flows along which fractional Dbranes either disappear or evolve into other fractional Dbranes, and other flows along
Four lectures on the gaugegravity correspondence
, 2003
"... We review in a pedagogical manner some of the efforts aiming to extend the gauge/gravity correspondence to nonconformal supersymmetric gauge theories in four dimensions. After giving a general overview, we discuss in detail two specific examples: fractional Dbranes on orbifolds and Dbranes wrappe ..."
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Cited by 18 (1 self)
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We review in a pedagogical manner some of the efforts aiming to extend the gauge/gravity correspondence to nonconformal supersymmetric gauge theories in four dimensions. After giving a general overview, we discuss in detail two specific examples: fractional Dbranes on orbifolds and Dbranes wrapped on supersymmetric cycles of CalabiYau spaces. We explore in particular which gauge theory information can be extracted from the corresponding supergravity solutions, and what the remaining open problems are. We also briefly explain the connection between these and other approaches, such as fractional branes on conifolds, branes suspended between branes, M5branes on Riemann surfaces and Mtheory on G2holonomy manifolds, and discuss the rôle played by geometric transitions in all that.
Localized tachyons and the quantum McKay correspondence
 JHEP
"... The condensation of closed string tachyons localized at the fixed point of a C d /Γ orbifold can be studied in the framework of renormalization group flow in a gauged linear sigma model. The evolution of the Higgs branch along the flow describes a resolution of singularities via the process of tachy ..."
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Cited by 16 (2 self)
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The condensation of closed string tachyons localized at the fixed point of a C d /Γ orbifold can be studied in the framework of renormalization group flow in a gauged linear sigma model. The evolution of the Higgs branch along the flow describes a resolution of singularities via the process of tachyon condensation. The study of the fate of Dbranes in this process has lead to a notion of a “quantum McKay correspondence. ” This is a hypothetical correspondence between fractional branes in an orbifold singularity in the ultraviolet with the Coulomb and Higgs branch branes in the infrared. In this paper we present some nontrivial evidence for this correspondence in the case C 2 / Zn by relating the intersection form of fractional branes to that of “Higgs branch branes, ” the latter being branes which wrap nontrivial cycles in the resolved space. Feb
Dbranes in a Big Bang/Big Crunch Universe: Misner Space
, 2005
"... We study Dbranes in a twodimensional Lorentzian orbifold R1,1 /Γ with a discrete boost Γ. This space is known as Misner or Milne space, and includes big crunch/big bang singularity. In this space, there are D0branes in spiral orbits and D1branes with or without flux on them. In particular, we ob ..."
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Cited by 15 (2 self)
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We study Dbranes in a twodimensional Lorentzian orbifold R1,1 /Γ with a discrete boost Γ. This space is known as Misner or Milne space, and includes big crunch/big bang singularity. In this space, there are D0branes in spiral orbits and D1branes with or without flux on them. In particular, we observe imaginary parts of partition functions, and interpret them as the rates of open string pair creation for D0branes and emission of winding closed strings for D1branes. These phenomena occur due to the timedependence of the background. Open string 2 → 2 scattering amplitude on a D1brane is also computed and found to be less singular than closed string case.
Holomorphic Tachyons and Fractional Dbranes
, 2001
"... We study tachyon condensation on braneantibrane systems in orbifold theories from the viewpoint of boundary string field theory. We show that the condensation of holomorphic tachyon fields generates various fractional Dbranes. The boundary N=2 supersymmetry in the worldsheet theory ensures this r ..."
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Cited by 13 (4 self)
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We study tachyon condensation on braneantibrane systems in orbifold theories from the viewpoint of boundary string field theory. We show that the condensation of holomorphic tachyon fields generates various fractional Dbranes. The boundary N=2 supersymmetry in the worldsheet theory ensures this result exactly. Furthermore, our results are consistent with the twisted RRcharges from detailed calculations of boundary states. We also discuss the generation of RRcharges due to holomorphic tachyon fields on multiple braneantibrane pairs in flat space.
Open strings in simple current orbifolds
"... We study branes and open strings in a large class of orbifold backgrounds using microscopic techniques of boundary conformal field theory. In particular, we obtain factorizing operator product expansions of open string vertex operators for such branes. Applications include branes in Z2 orbifolds of ..."
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Cited by 11 (2 self)
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We study branes and open strings in a large class of orbifold backgrounds using microscopic techniques of boundary conformal field theory. In particular, we obtain factorizing operator product expansions of open string vertex operators for such branes. Applications include branes in Z2 orbifolds of the SU(2) WZW model and in the Dseries of unitary minimal models considered previously by Runkel.
World volume action for fractional branes
 Nucl. Phys. B
"... We study the world volume action of fractional Dpbranes of type IIA string theory compactified on the orbifold T 4 /Z2. The geometric relation between these branes and wrapped branes is investigated using conformal techniques. In particular we examine in detail various scattering amplitudes and fin ..."
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Cited by 8 (4 self)
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We study the world volume action of fractional Dpbranes of type IIA string theory compactified on the orbifold T 4 /Z2. The geometric relation between these branes and wrapped branes is investigated using conformal techniques. In particular we examine in detail various scattering amplitudes and find that the leading lowenergy interactions are consistent with the boundary action derived geometrically. Work partially supported by the EC RTN programme HPRNCT200000131 in which G.S. is associated
Profiling the brane drain in a nonsupersymmetric orbifold
 JHEP 0601
, 2006
"... We study Dbranes in a nonsupersymmetric orbifold of type C 2 /Γ, perturbed by a tachyon condensate, using a gauged linear sigma model. The RG flow has both higgs and coulomb branches, and each branch supports different branes. The coulomb branch branes account for the “brane drain ” from the higgs ..."
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Cited by 7 (1 self)
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We study Dbranes in a nonsupersymmetric orbifold of type C 2 /Γ, perturbed by a tachyon condensate, using a gauged linear sigma model. The RG flow has both higgs and coulomb branches, and each branch supports different branes. The coulomb branch branes account for the “brane drain ” from the higgs branch, but their precise relation to fractional branes has hitherto been unknown. Building on the results of hepth/0403016 we construct, in detail, the map between fractional branes and the coulomb/higgs branch branes for two examples in the type 0 theory. This map depends on the phase of the tachyon condensate in a surprising and intricate way. In the mirror LandauGinzburg picture the dependence on the tachyon phase is manifested by discontinuous changes in the shape of the Dbrane. July 20, 2005 1. Introduction and
Dbranes in Melvin background
 JHEP 0111, 036 (2001) [arXiv:hepth/0110200]; T. Takayanagi and T. Uesugi, “Flux stabilization of Dbranes in NSNS Melvin background,” Phys. Lett. B 528
, 2002
"... In this paper we discuss Dbranes in the Melvin background and its supersymmetric generalizations. In particular we determine the Dbrane spectra in these backgrounds by constructing their boundary states explicitly, where some of the Dbranes are supersymmetric. The results sensitively depend on wh ..."
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Cited by 5 (3 self)
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In this paper we discuss Dbranes in the Melvin background and its supersymmetric generalizations. In particular we determine the Dbrane spectra in these backgrounds by constructing their boundary states explicitly, where some of the Dbranes are supersymmetric. The results sensitively depend on whether the value of magnetic flux in the Melvin background is rational or irrational. For the rational case the Dbranes are regarded as the generalizations of fractional Dbranes in abelian orbifolds Cn /ZN of type II or type 0 string theory. For the irrational case we found a very limited spectrum. Since the background includes the nontrivial Hflux, the Dbranes will provide interesting examples from the viewpoint of the noncommutative geometry.