Volume 42, Issue 7, July 2001
Index of content:
- SPECIAL ISSUE: STRINGS, BRANES, AND M-THEORY
- STRINGS AND D-BRANES
42(2001); http://dx.doi.org/10.1063/1.1372176View Description Hide Description
The Hagedorn transition in noncommutative open string theory (NCOS) is relatively simple because gravity decouples. For NCOS theories in no more than five space–time dimensions, the Hagedorn transition is second order, and the high temperature phase involves long, nearly straight fundamental strings separating from the D-brane on which the NCOS theory is defined. Above five spacetime dimensions interaction effects become important below the Hagedorn temperature. Although this complicates studies of the transition, we believe that the high temperature phase again involves long strings liberated from the bound state.
42(2001); http://dx.doi.org/10.1063/1.1377270View Description Hide Description
We show that the relation between D-branes and noncommutative tachyons leads very naturally to the relation between D-branes and K-theory. We also discuss some relations between D-branes and K-homology, provide a noncommutative generalization of the ABS construction, and give a simple physical interpretation of Bott periodicity. In addition, a framework for constructing Neveu–Schwarz fivebranes as noncommutative solitons is proposed.
42(2001); http://dx.doi.org/10.1063/1.1377275View Description Hide Description
We discuss the non-Abelian world-volume action which governs the dynamics of coincident -branes. In this theory, the branes’ transverse displacements are described by matrix-valued scalar fields, and so this is a natural physical framework for the appearance of noncommutative geometry. One example is the dielectric effect by which -branes may be polarized into a noncommutative geometry by external fields. Another example is the appearance of noncommutative geometries in the description of intersecting D-branes of differing dimensions, such as D-strings ending on a D3- or D5-brane. We also describe the related physics of giant gravitons.
42(2001); http://dx.doi.org/10.1063/1.1376161View Description Hide Description
We embed the large N Chern–Simons/topological string duality in ordinary superstrings. This corresponds to a large N duality between generalized gauge systems with supersymmetry in four dimensions and superstrings propagating on noncompact Calabi–Yau manifolds with certain fluxes turned on. We also show that in a particular limit of the gauge theory system, certain superpotential terms in the system (including deformations if spacetime is noncommutative) are captured to all orders in by the amplitudes of noncritical bosonic strings propagating on a circle with self-dual radius. We also consider D-brane/anti-D-brane system wrapped over vanishing cycles of compact Calabi–Yau manifolds and argue that at large N they induce a shift in the background to a topologically distinct Calabi–Yau, which we identify as the ground state system of the brane/anti-brane system.
42(2001); http://dx.doi.org/10.1063/1.1374448View Description Hide Description
We show that boundary conditions in topological open string theory on Calabi–Yau (CY) manifolds are objects in the derived category of coherent sheaves, as foreseen in the homological mirror symmetry proposal of Kontsevich. Together with conformal field theory considerations, this leads to a precise criterion determining the supersymmetry preserving branes at any point in CY moduli space, completing the proposal of II-stability.
42(2001); http://dx.doi.org/10.1063/1.1377037View Description Hide Description
We show that the world-volume theory on a -brane at the tachyonic vacuum has solitonic string solutions whose dynamics is governed by the Nambu–Goto action of a string moving in dimensional space–time. This provides strong evidence for the conjecture that at this vacuum the full dimensional Poincaré invariance is restored. We also use this result to argue that the open string field theory at the tachyonic vacuum must contain closed string excitations.
42(2001); http://dx.doi.org/10.1063/1.1376129View Description Hide Description
Motivated by recent discussions of actions for tachyon and vector fields related to tachyon condensation in open string theory we review and clarify some aspects of their derivation within the sigma model approach. In particular, we demonstrate that the renormalized partition function of the boundary sigma model gives the effective action for massless vectors which is consistent with the string S-matrix and beta function, resolving an old problem with this suggestion in the bosonic string case at the level of the leading derivative corrections to Born–Infeld action. We give a manifestly gauge invariant definition of in non-Abelian NSR open string theory and check that its derivative reproduces the tachyon beta function in a particular scheme. We also discuss the derivation of similar actions for tachyon and massless modes in closed bosonic and NSR (type 0) string theories. In the bosonic case the tachyon potential has the structure but it vanishes in the NSR string case.
42(2001); http://dx.doi.org/10.1063/1.1374449View Description Hide Description
We define an iterative procedure to obtain a non-Abelian generalization of the Born–Infeld action. This construction is made possible by the use of the severe restrictions imposed by kappa-symmetry. In this paper we will present all bosonic terms in the action up to terms quartic in the Yang–Mills field strength and all fermion bilinear terms up to terms cubic in the field strength. Already at this order the fermionic terms do not satisfy the symmetric trace-prescription.
42(2001); http://dx.doi.org/10.1063/1.1377276View Description Hide Description
Prophesy is just for fun. The more useful purpose of the exercise is to identify important issues and to stimulate thought about where they stand and how they might be resolved. The subject areas that are fair game include all of particle physics and cosmology.
- ADS/CFT DUALITY
42(2001); http://dx.doi.org/10.1063/1.1372177View Description Hide Description
We propose that the expectation value of a circular BPS-Wilson loop in supersymmetric Yang–Mills can be calculated exactly, to all orders in a expansion and to all orders in Using the AdS/CFT duality, this result yields a prediction of the value of the string amplitude with a circular boundary to all orders in α′ and to all orders in We then compare this result with string theory. We find that the gauge theory calculation, for large and to all orders in the expansion, does agree with the leading string theory calculation, to all orders in and to lowest order in α′. We also find a relation between the expectation value of any closed smooth Wilson loop and the loop related to it by an inversion that takes a point along the loop to infinity, and compare this result, again successfully, with string theory.
Finite N AdS/CFT correspondence for Abelian and non-Abelian orbifolds, and gauge coupling unification42(2001); http://dx.doi.org/10.1063/1.1374450View Description Hide Description
Although the AdS/CFT correspondence is rigorous only for an infinite stack of D3-branes, it can be fruitfully studied for finite as a source of gauge structures and choices for chiral fermions and complex scalars which solve the hierarchy problem by a conformal fixed point. We emphasize orbifolds where the resulting GFT has N=0 supersymmetry. The fact that the complex scalars are prescribed by the construction limits the possible spontaneous symmetry breaking. Both Abelian and non-Abelian Γ are illustrated by simple examples. An accurate in electroweak unification can be obtained, suggesting that this approach merits further study.
42(2001); http://dx.doi.org/10.1063/1.1377273View Description Hide Description
In this paper we study the spectrum of bosonic string theory on We study classical solutions of the WZW model, including solutions for long strings with nonzero winding number. We show that the model has a symmetry relating string configurations with different winding numbers. We then study the Hilbert space of the WZW model, including all states related by the above symmetry. This leads to a precise description of long strings. We prove a no-ghost theorem for all the representations that are involved and discuss the scattering of the long string.
42(2001); http://dx.doi.org/10.1063/1.1377039View Description Hide Description
We consider the one-loop partition function for Euclidean BTZ black hole back-grounds or equivalently thermal backgrounds which are quotients of (Euclidean The one-loop partition function is modular invariant and we can read off the spectrum which is consistent to that found in hep-th/0001053. We see long strings and discrete states in agreement with the expectations.
42(2001); http://dx.doi.org/10.1063/1.1373423View Description Hide Description
This review gives results on vertex operators for the Type IIB superstring in an background with Ramond–Ramond flux, which were presented at Strings 2000. Constraint equations for these vertex operators are derived, and their components are shown to satisfy the supergravity linearized equations of motion for the six-dimensional (2, 0) theory of a supergravity and tensor multiplet expanded around space-time.
42(2001); http://dx.doi.org/10.1063/1.1377274View Description Hide Description
We discuss superparticle and superstring dynamics in supported by R–R 3-form background using light-cone gauge approach. Starting with the superalgebra representing the basic symmetry of this background we find the light-cone superparticle Hamiltonian. We determine the harmonic decomposition of light-cone superfield describing fluctuations of type IIB supergravity fields expanded near background and thus the corresponding Kaluza–Klein spectrum. We fix the fermionic and bosonic light-cone gauges in the covariant Green–Schwarz superstring action and find the corresponding light-cone string Hamiltonian. We also obtain a realization of the generators of in terms of the superstring 2-d fields in the light-cone gauge.
42(2001); http://dx.doi.org/10.1063/1.1374451View Description Hide Description
We perform a general analysis of representations of the superconformal algebras OSp(8/4, R) and in harmonic superspace. We present a construction of their highest-weight UIR’s by multiplication of the different types of massless conformal superfields (“supersingletons”). In particular, all “short multiplets” are classified. Representations undergoing shortening have “protected dimension” and may correspond to BPS states in the dual supergravitytheory in anti-de Sitter space. These results are relevant for the classification of multitrace operators in boundary conformally invariant theories as well as for the classification of AdS black holes preserving different fractions of supersymmetry.
42(2001); http://dx.doi.org/10.1063/1.1372698View Description Hide Description
We show that an earlier domain wall solution of type IIB supergravity provides a supersymmetric realization of the Randall–Sundrum brane-world, and give its ten-dimensional interpretation in terms of IIB 3-branes. We also explain how previous no-go theorems are circumvented. In particular, whereas supergravity scalars have energy and are unable to support a positive tension brane, our scalar has and is the breathing mode of the compactification. Another essential element of the construction is the implementation of a symmetry by patching together compactifications with opposite signs for their 5-form field strengths. This is thus a IIB analog of a previous 3-brane realization of the Hořava–Witten orbifold. A mode-locking phenomenon avoids the appearance of negative energy zero-modes in spite of the necessity of a negative tension brane-source.
42(2001); http://dx.doi.org/10.1063/1.1377272View Description Hide Description
We present a systematic study of a new type of consistent “brane-world Kaluza–Klein reduction,” which describes fully nonlinear deformations of codimension one objects that arise as solutions of a large class of gauged supergravitytheories in diverse dimensions, and whose world-volume theories are described by ungauged supergravities with-one half of the original supersymmetry. In addition, we provide oxidations of these ansätz which are in general related to sphere compactified higher dimensional string theory or M-theory. Within each class we also provide explicit solutions of brane configurations localized on the world-brane. We show that at the Cauchy horizon (in the transverse dimension of the consistently Kaluza–Klein reduced world-brane) there is a curvature singularity for any configuration with a non-null Riemann curvature or a nonvanishing Ricci scalar that lives in the world-brane. Since the massive Kaluza–Klein modes can be consistently decoupled, they cannot participate in regulating these singularities.
42(2001); http://dx.doi.org/10.1063/1.1373424View Description Hide Description
We study supersymmetric domain walls on orbifolds. The supergravity solutions in the bulk are given by the attractor equation associated with Calabi–Yau (CY) spaces and have a naked space–time singularity at some We are looking for possibilities to cut off this singularity with the second wall by a stringy mechanism. We use the collapse of the CY cycle at which happens before and at a finite distance from the space–time singularity. In our example with three Kähler moduli the second wall is at the end of the moduli space at where also the enhancement of SU(2) gauge symmetry takes place so that The physics of the excision of a naked singularity via the enhançon in the context of domain wall has an interpretation on the heterotic side related to duality. The position of the enhançon is given by the equation
42(2001); http://dx.doi.org/10.1063/1.1377036View Description Hide Description
We investigate aspects of the four-dimensional (4D) effective description of brane world scenarios based on warped compactification on anti-de Sitter space. The low-energy dynamics is described by visible matter gravitationally coupled to a “dark” conformal field theory. We give the linearized description of the 4D stress tensor corresponding to an arbitrary 5D matter distribution. In particular a 5D falling particle corresponds to a 4D expanding shell, giving a 4D interpretation of a trajectory that misses a black hole only by moving in the fifth dimension. Breakdown of the effective description occurs when either five-dimensional physics or strong gravity becomes important. In scenarios with a TeV brane, the latter can happen through the production of black holes near the TeV scale. This could provide an interesting experimental window on quantum black hole dynamics.