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39
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.
Closed strings tachyons and noncommutative instabilities,” JHEP 0302
, 2003
"... We observe a relation between closed strings tachyons and oneloop instabilities in nonsupersymmetric noncommutative gauge theories. In particular we analyze the spectra of type IIB string theory on C 3 /ZN orbifold singularities and the noncommutative field theory that lives on D3 branes located ..."
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Cited by 15 (2 self)
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We observe a relation between closed strings tachyons and oneloop instabilities in nonsupersymmetric noncommutative gauge theories. In particular we analyze the spectra of type IIB string theory on C 3 /ZN orbifold singularities and the noncommutative field theory that lives on D3 branes located at the singularity. We find a surprising correspondence between the existence or not of oneloop lowmomentum instabilities in the noncommutative field theory and the existence or not of tachyons in the closed string twisted sectors. Moreover, the relevant piece of the noncommutative field theory effective action is suggestive of an exchange of closed string modes. This suggests that noncommutative field theories retain some information about the dynamics of the underlying string configuration. Finally, we also comment on a possible relation between closed string tachyon
Noncommutative Standard Modelling
, 2004
"... We present a noncommutative gauge theory that has the ordinary Standard Model as its lowenergy limit. The model is based on the gauge group U(4) × U(3) × U(2) and is constructed to satisfy the key requirements imposed by noncommutativity: the UV/IR mixing effects, restrictions on representations ..."
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Cited by 9 (3 self)
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We present a noncommutative gauge theory that has the ordinary Standard Model as its lowenergy limit. The model is based on the gauge group U(4) × U(3) × U(2) and is constructed to satisfy the key requirements imposed by noncommutativity: the UV/IR mixing effects, restrictions on representations and charges of matter fields, and the cancellation of noncommutative gauge anomalies. At energies well below the noncommutative mass scale our model flows to the commutative Standard Model plus additional free U(1) degrees of freedom which are decoupled due to the UV/IR mixing. Our model also predicts
Nonplanar anomalies in noncommutative theories and the Green–Schwarz mechanism, JHEP 0206
, 2002
"... We discuss nonplanar anomalies in noncommutative gauge theories. In particular we show that a nonplanar anomaly exists when the external noncommutative momentum is zero and that it leads to a nonconservation of the associated axial charge. In the case of nonplanar local anomalies, a cancellation of ..."
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Cited by 8 (2 self)
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We discuss nonplanar anomalies in noncommutative gauge theories. In particular we show that a nonplanar anomaly exists when the external noncommutative momentum is zero and that it leads to a nonconservation of the associated axial charge. In the case of nonplanar local anomalies, a cancellation of the anomaly can be achieved by a GreenSchwarz mechanism. In an example of D3 branes placed on an orbifold singularity that leads to a chiral theory, the mechanism involves twisted RR fields which propagate with zero noncommutative momentum. Global anomalies are not cancelled and, in particular, the Anomalies play a fundamental role in particle physics [1]. In field theory, local anomalies signal an inconsistency of the theory and are therefore considered as ‘bad’. Global anomalies are ‘good ’ since they allow decay processes, such as π 0 → 2γ, which are classically forbidden but observed in nature. Through
Emergent Gravity, Matrix Models and UV/IR Mixing
, 2008
"... We verify explicitly that UV/IR mixing for noncommutative gauge theory can be understood in terms of an induced gravity action, as predicted by the identification [1] of gravity within matrix models of NC gauge theory. More precisely, we obtain the EinsteinHilbert action by integrating out a scalar ..."
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Cited by 8 (1 self)
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We verify explicitly that UV/IR mixing for noncommutative gauge theory can be understood in terms of an induced gravity action, as predicted by the identification [1] of gravity within matrix models of NC gauge theory. More precisely, we obtain the EinsteinHilbert action by integrating out a scalar field in the adjoint. It arises from the wellknown UV/IR mixing of NC gauge theory, which is carefully reanalyzed and interpreted in terms of gravity. The matrix model therefore contains gravity as an IR effect, due to UV/IR mixing.
Noncommutative U(1) SuperYangMills Theory: Perturbative SelfEnergy Corrections, preprint hepth/0203141
"... MaxPlanckInstitute for Mathematics in the Sciences ..."
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Cited by 7 (2 self)
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MaxPlanckInstitute for Mathematics in the Sciences
Noncommutativity from the string perspective: modification of gravity at a mm without mm sized extra dimensions
, 2006
"... ..."
Aspects of openclosed duality in a background Bfield
 J. High Energy Phys
"... We study closed string exchanges in background Bfield. By analysing the two point one loop amplitude in bosonic string theory, we show that treelevel exchange of lowest lying, tachyonic and massless closed string modes, have IR singularities similar to those of the nonplanar sector in noncommutati ..."
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Cited by 7 (3 self)
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We study closed string exchanges in background Bfield. By analysing the two point one loop amplitude in bosonic string theory, we show that treelevel exchange of lowest lying, tachyonic and massless closed string modes, have IR singularities similar to those of the nonplanar sector in noncommutative gauge theories. We further isolate the contributions from each of the massless modes. We interpret these results as the manifestation of open/closed string duality, where the IR behaviour of the boundary noncommutative gauge theory is reconstructed from the bulk theory of closed strings.
NonPerturbative Planar Equivalence and the Absence of Closed String Tachyons
 JHEP
"... Abstract: We consider ’orbifold ’ and ’orientifold ’ field theories from the dual closed string theory side. We argue that a necessary condition for planar equivalence to hold is the absence of a closed string tachyonic mode in the dual nonsupersymmetric string. We analyze several gauge theories on ..."
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Cited by 6 (2 self)
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Abstract: We consider ’orbifold ’ and ’orientifold ’ field theories from the dual closed string theory side. We argue that a necessary condition for planar equivalence to hold is the absence of a closed string tachyonic mode in the dual nonsupersymmetric string. We analyze several gauge theories on R 3 × S 1. In the specific case of U(N) theories with symmetric/antisymmetric fermions (’orientifold field theories’) the relevant closed string theory is tachyonfree at large compactification radius (due to winding modes), but it develops a tachyonic mode below a critical radius. Our finding is with agreement with field theory expectations of a phase transition from a Cparity violating phase to a Cparity preserving phase as the compactification radius increases. In the case of U(N) × U(N) theories with bifundamental matter (’orbifold field theories’) a tachyon is always present in the string spectrum, at any compactification radius. We conclude that on R 4 planar equivalence holds for ’orientfiold field theories’, but fails for ’orbifold field theories’. We also discuss examples of SO/Sp gauge theories with symmetric/antisymmetric fermions. In this case planar equivalence holds at any compactification radius in agreement with the absence of tachyons in the string dual. Keywords: AdS/CFT, large N, Branes. – 1 – 1.