Conifold Geometry Research Articles

Topology-changing horizons at large D as Ricci flows

The topology-changing transition between black strings and black holes localized in a Kaluza-Klein circle is investigated in an expansion in the inverse of the number of dimensions D. Performing a new kind of large-D scaling reduces the problem to a Ricci flow of the near-horizon geometry as it varies along the circle direction. The flows of interest here simplify to a non-linear logarithmic diffusion equation, with solutions known in the literature which are interpreted as the smoothed conifold geometries involved in the transition, namely, split and fused cones, which connect to black holes and non-uniform black strings away from the conical region. Our study demonstrates the adaptability of the 1/D expansion to deal with all the regimes and aspects of the static black hole/black string system, and provides another instance of the manner in which the large D limit reduces the task of solving Einstein’s equations to a simpler but compelling mathematical problem.

Type IIA Klebanov-Strassler: the hard way

We construct the T-dual of the Klebanov-Strassler solution on a small region at the tip of the deformed conifold. The isometry coordinate we choose is the correct one to obtain an NS5 brane wrapping a holomorphic curve in Type IIA, as shown by a thorough analysis of the deformed conifold geometry. The shape of the locus wrapped by the NS5 brane matches the predictions from the Type IIA brane engineering construction dual to the $SU(N+M) \times SU(N)$ cascading gauge theory. The same isometry is then used to T-dualize the solution obtained by adding backreacted D3 branes to the Klebanov-Strassler solution. Our construction is the first step in a program to test the stability of antibranes in Type IIA backgrounds.

Geometric constructions of two-dimensional (0,2) SUSY theories

We consider the field theories on multiple stacks of D5 branes wrapped on four cycles of resolved/deformed conifold geometries fibered over a two torus. The central charges of the D5 branes are slightly misaligned when the branes are wrapped on various rigid holomorphic two cycles or when they have different charges with respect to a magnetic flux turned on the two torus. The wrapped D5 branes preserve (0,2) supersymmetry in two dimensions if the Kahler moduli and the magnetic flux are related. Our geometries are T-dual to the brane configurations considered by Kutasov-Lin and we provide a geometric interpretation for their equality between the field theory D-terms and the magnetic fluxes. We also consider the geometric transitions for rigid holomorphic two cycles fibered over a two torus with magnetic flux and discuss the partial breaking of supersymmetry after the geometric transitions.

A deformed conifold with a cosmological constant

We find a new regular solution of six-dimensional Einstein's equations with a positive cosmological constant. It has the same isometry group as the (deformed) conifold geometry, and the superpotential approach is used to solve the equations of motion. The space is compact and interpolates between the deformed conifold and the resolved cone with a blown-up four cycle. The deformation/resolution parameters are set by the cosmological constant.

Cascading gauge theory on [formula omitted] and String Theory landscape

Placing anti-D3 branes at the tip of the conifold in Klebanov–Strassler geometry provides a generic way of constructing meta-stable de Sitter (dS) vacua in String Theory. A local geometry of such vacua exhibit gravitational solutions with a D3 charge measured at the tip opposite to the asymptotic charge. We discuss a restrictive set of such geometries, where anti-D3 branes are smeared at the tip. Such geometries represent holographic dual of cascading gauge theory in dS4 with or without chiral symmetry breaking. We find that in the phase with unbroken chiral symmetry the D3 charge at the tip is always positive. Furthermore, this charge is zero in the phase with spontaneously broken chiral symmetry. We show that the effective potential of the chirally symmetric phase is lower than that in the symmetry broken phase, i.e., there is no spontaneous chiral symmetry breaking for cascading gauge theory in dS4. The positivity of the D3 brane charge in smooth de-Sitter deformed conifold geometries with fluxes presents difficulties in uplifting AdS vacua to dS ones in String Theory via smeared anti-D3 branes.

Non-extremal geometries and holographic phase transitions

Using the low energy limit of type IIB superstring theory, we obtain the non-extremal limit of deformed conifold geometry which is dual to the IR limit of large N thermal QCD.At low temperatures, the extremal geometry without black hole is favored while at high temperatures, the field theory is described by non-extremal black hole geometry. We compute the ten dimensional on shell action for extremal and non-extremal geometries and demonstrate that at a critical temperature $T_c$ there is a first order confinement to deconfinement phase transition. We compute $T_c$ as a function of 'tHooft coupling and study the thermodynamics of the dual gauge theory by evaluating the free energy and entropy of the ten dimensional geometry. We find agreement with the conformal limit while thermodynamics of non-conformal strongly coupled gauge theories is explored using the black hole geometries in non-AdS space.

Nekrasov's Partition Function and Refined Donaldson-Thomas Theory: the Rank One Case

This paper studies geometric engineering, in the simplest possible case of rank one (Abelian) gauge theory on the affine plane and the resolved conifold. We recall the identification between Nekrasov's partition function and a version of refined Donaldson-Thomas theory, and study the relationship between the underlying vector spaces. Using a purity result, we identify the vector space underlying refined Donaldson-Thomas theory on the conifold geometry as the exterior space of the space of polynomial functions on the affine plane, with the (Lefschetz) SL(2)-action on the threefold side being dual to the geometric SL(2)-action on the affine plane. We suggest that the exterior space should be a module for the (explicitly not yet known) cohomological Hall algebra (algebra of BPS states) of the conifold.

Large N Duality, Lagrangian Cycles, and Algebraic Knots

We consider knot invariants in the context of large $N$ transitions of topological strings. In particular we consider aspects of Lagrangian cycles associated to knots in the conifold geometry. We show how these can be explicity constructed in the case of algebraic knots. We use this explicit construction to explain a recent conjecture relating study of stable pairs on algebraic curves with HOMFLY polynomials. Furthermore, for torus knots, using the explicit construction of the Lagrangian cycle, we also give a direct A-model computation and recover the HOMFLY polynomial for this case.

Chiral modulations in curved space II: conifold geometries

In this paper, we extend our previous analysis concerning the formation of inhomogeneous condensates in strongly-coupled fermion effective field theories on curved spaces and include the case of conifold geometries that represent the simplest tractable case of manifolds with curvature singularities. In the set-up considered here, by keeping the genuine thermodynamical temperature constant, we may single out the role that curvature effects play on the breaking/restoration of chiral symmetry and on the appearance of inhomogeneous phases. The first goal of this paper is to construct a general expression of the finite temperature effective action for inhomogeneous condensates in the case of four-fermion effective field theories on conifold geometries with generic Riemannian smooth base (generalised cones). The other goal is to implement numerically the above formal results and construct self-consistent solutions for the condensate. We explicitly show that the condensate assumes a kink-like profile, vanishing at the singularity that is surrounded by a bubble of restored chiral symmetry phase.

Refined cigar and Ω-deformed conifold

Antoniadis et al proposed a relation between the Omega-deformation and refined correlation functions of the topological string theory. We investigate the proposal for the deformed conifold geometry from a non-compact Gepner model approach. The topological string theory on the deformed conifold has a dual description in terms of the c=1 non-critical string theory at the self-dual radius, and the Omega-deformation yields the radius deformation. We show that the refined correlation functions computed from the twisted SL(2,R)/U(1) Kazama-Suzuki coset model at level k=1 have direct c=1 non-critical string theory interpretations. After subtracting the leading singularity to procure the 1PI effective action, we obtain the agreement with the proposal.

The evolution of conifolds

We simulate the gravitational dynamics of the conifold geometries (resolved and deformed) involved in the description of certain compact spacetimes. As the cycles of the conifold collapse towards a singular geometry we find that a horizon develops, shielding the external spacetime from the curvature singularity of the newly formed black hole. The structure of the black hole is examined for a range of initial conditions, and we find a candidate black-hole solution for the final state of the collapse.

Conifolds and geometric transitions

Conifold geometries have recieved much attention in string theory and string-inspired cosmology recently, in particular the Klebanov-Strassler background that is known as the ''warped throat.'' This paper provides a pedagogical explanation for the singularity resolution in this geometry and emphasizes its connection to geometric transitions. The first part focuses on the gauge theory dual to the Klebanov-Strassler background, including the T-dual intersecting branes description. Then, a connection to the Gopakumar-Vafa conjecture for open-closed string duality is presented and a series of papers verifying this model on the supergravity level is summarized. An appendix provides extensive background material about conifold geometries. Special attention is given to their complex structures and the supersymmetry conditions on the background flux in constructions with fractional D3-branes on the singular (Klebanov-Tseytlin) and resolved (Pando Zayas-Tseytlin) conifolds are reevaluated. In agreement with earlier results, it is shown that only the singular solution allows a supersymmetric flux. However, the importance of using the correct complex structure to reach this conclusion is emphasized.

Brane inflation and the WMAP data: a Bayesian analysis

The Wilkinson Microwave Anisotropy Probe (WMAP) constraints on string inspired ‘braneinflation’ are investigated. Here, the inflaton field is interpreted as the distancebetween two branes placed in a flux-enriched background geometry and has aDirac–Born–Infeld (DBI) kinetic term. Our method relies on an exact numericalintegration of the inflationary power spectra coupled to a Markov chain Monte Carloexploration of the parameter space. This analysis is valid for any perturbativevalue of the string coupling constant and of the string length, and includes aphenomenological modelling of the reheating era to describe the post-inflationaryevolution. It is found that the data favour a scenario where inflation stops byviolation of the slow-roll conditions well before brane annihilation, rather than bytachyonic instability. As regards the background geometry, it is established thatlogv>−10 at95% confidence level(CL), where v is the dimensionless ratio of the five-dimensional sub-manifold at the baseof the six-dimensional warped conifold geometry to the volume of theunit 5-sphere. The reheating energy scale remains poorly constrained,Treh>20 GeV at95% CL, for an extreme equation of state () only. Assuming that the string length is known, the favoured values of the stringcoupling and of the Ramond–Ramond total background charge appear to be correlated.Finally, the stochastic regime (without and with volume effects) is studied using aperturbative treatment of the Langevin equation. The validity of such an approximatescheme is discussed and shown to be too limited for a full characterization of the quantumeffects.

Gravity dual of metastable dynamical supersymmetry breaking

Metastable, supersymmetry-breaking configurations can be created in flux geometries by placing antibranes in warped throats. Via gauge/gravity duality, such configurations should have an interpretation as supersymmetry-breaking states in the dual field theory. In this paper, we perturbatively determine the asymptotic supergravity solutions corresponding to anti-D3-brane probes placed at the tip of the cascading warped deformed conifold geometry, which is dual to an SU(N+M) x SU(N) gauge theory. The backreaction of the antibranes has the effect of introducing imaginary anti-self-dual flux, squashing the compact part of the space and forcing the dilaton to run. Using the generalization of holographic renormalization to cascading geometries, we determine the expectation values of operators in the dual field theory in terms of the asymptotic values of the supergravity fields.

Super Calabi-Yau's and special Lagrangians

We apply mirror symmetry to the super Calabi-Yau manifold CP^{(n|n+1)} and show that the mirror can be recast in a form which depends only on the superdimension and which is reminiscent of a generalized conifold. We discuss its geometrical properties in comparison to the familiar conifold geometry. In the second part of the paper examples of special-Lagrangian submanifolds are constructed for a class of super Calabi-Yau's. We finally comment on their infinitesimal deformations.

Wilson loops, geometric transitions and bubbling Calabi-Yau's

Motivated by recent developments in the AdS/CFT correspondence, we provide several alternative bulk descriptions of an arbitrary Wilson loop operator in Chern-Simons theory. Wilson loop operators in Chern-Simons theory can be given a description in terms of a configuration of branes or alternatively anti-branes in the resolved conifold geometry. The representation of the Wilson loop is encoded in the holonomy of the gauge field living on the dual brane configuration. By letting the branes undergo a new type of geometric transition, we argue that each Wilson loop operator can also be described by a bubbling Calabi-Yau geometry, whose topology encodes the representation of the Wilson loop. These Calabi-Yau manifolds provide a novel representation of knot invariants. For the unknot we confirm these identifications to all orders in the genus expansion.

Fractional branes and the gravity dual of partial supersymmetry breaking

In type IIB string theory, we consider fractional D3-branes in the orbifold background dual to four-dimensional N = 2 supersymmetric Yang–Mills theory. We find the gravitational dual description of the generation of a non-trivial field theory potential on the Coulomb branch. When the orbifold singularity is softened to the smooth Eguchi–Hanson space, the resulting potential induces spontaneous partial supersymmetry breaking. We study the N = 1 theory arising in those vacua and we see how the resolved conifold geometry emerges in this way. It will be natural to identify the size of the blown-up two-cycle of that geometry with the inverse mass of the adjoint chiral scalar. We finally discuss the issue of geometric transition in this context.

Topological strings and largeNphase transitions I: Nonchiral expansion ofq-deformed Yang-Mills theory

We examine the problem of counting bound states of BPS black holes on local Calabi-Yau threefolds which are fibrations over a Riemann surface by computing the partition function of q-deformed Yang-Mills theory on the Riemann surface. We study in detail the genus zero case and obtain, at finite N, the instanton expansion of the gauge theory. It can be written exactly as the partition function for U(N) Chern-Simons gauge theory on a Lens space, summed over all non-trivial vacua, plus a tower of non-perturbative instanton contributions. The correspondence between two and three dimensional gauge theories is elucidated by an explicit mapping between two-dimensional Yang-Mills instantons and flat connections on the Lens space. In the large N limit we find a peculiar phase structure in the model. At weak string coupling the theory reduces exactly to the trivial flat connection sector with instanton contributions exponentially suppressed, and the topological string partition function on the resolved conifold is reproduced in this regime. At a certain critical point all non-trivial vacua contribute, instantons are enhanced and the theory appears to undergo a phase transition into a strong coupling regime. We rederive these results by performing a saddle-point approximation to the exact partition function. We obtain a q-deformed version of the Douglas-Kazakov equation for two-dimensional Yang-Mills theory on the sphere, whose one-cut solution below the transition point reproduces the resolved conifold geometry. Above the critical point we propose a two-cut solution that should reproduce the chiral-antichiral dynamics found for black holes on the Calabi-Yau threefold and the Gross-Taylor string in the undeformed limit. The transition from the strong coupling phase to the weak coupling phase appears to be of third order.

Conifold geometries, topological strings, and multimatrix models

We study open B-model representing D-branes on 2-cycles of local Calabi--Yau geometries. To this end we work out a reduction technique linking D-branes partition functions and multi-matrix models in the case of conifold geometries so that the matrix potential is related to the complex moduli of the conifold. We study the geometric engineering of the multi-matrix models and focus on two-matrix models with bilinear couplings. We show how to solve this models in an exact way, without resorting to the customary saddle point/large N approximation. The method consists of solving the quantum equations of motion and using the flow equations of the underlying integrable hierarchy to derive explicit expressions for correlators. Finally we show how to incorporate in this formalism the description of several group of D-branes wrapped around different cycles.

D-brane propagation in two-dimensional black hole geometries

We study propagation of D0-brane in two-dimensional Lorentzian black hole backgrounds by the method of boundary conformal field theory of SL(2,R)/U(1) supercoset at level k. Typically, such backgrounds arise as near-horizon geometries of k coincident non-extremal NS5-branes, where 1/k measures curvature of the backgrounds in string unit and hence size of string worldsheet effects. At classical level, string worldsheet effects are suppressed and D0-brane propagation in the Lorentzian black hole geometry is simply given by the Wick rotation of D1-brane contour in the Euclidean black hole geometry. Taking account of string worldsheet effects, boundary state of the Lorentzian D0-brane is formally constructible via Wick rotation from that of the Euclidean D1-brane. However, the construction is subject to ambiguities in boundary conditions. We propose exact boundary states describing the D0-brane, and clarify physical interpretations of various boundary states constructed from different boundary conditions. As it falls into the black hole, the D0-brane radiates off to the horizon and to the infinity. From the boundary states constructed, we compute physical observables of such radiative process. We find that part of the radiation to infinity is in effective thermal distribution at the Hawking temperature. We also find that part of the radiation to horizon is in the Hagedorn distribution, dominated by massive, highly non-relativistic closed string states, much like the tachyon matter. Remarkably, such distribution emerges only after string worldsheet effects are taken exactly into account. From these results, we observe that nature of the radiation distribution changes dramatically across the conifold geometry k=1 (k=3 for the bosonic case), exposing the `string - black hole transition' therein.