arXiv subjects

Kyriakos Papadodimas

Publications and source records attributed to Kyriakos Papadodimas.

43 records · Page 3Linked to original sources

arXiv2007

Nonsupersymmetric Brane/Antibrane Configurations in Type IIA and M Theory

We study metastable nonsupersymmetric configurations in type IIA string theory, obtained by suspending D4-branes and anti-D4-branes between holomorphically curved NS5's, which are related to those of hep-th/0610249 by T-duality. When the numbers of branes and antibranes are the same, we are able to obtain an exact M theory lift which can be used to reliably describe the vacuum configuration as a curved NS5 with dissolved RR flux for g_s<<1 and as a curved M5 for g_s>>1. When our weakly coupled description is reliable, it is related by T-duality to the deformed IIB geometry with flux of hep-th/0610249 with moduli exactly minimizing the potential derived therein using special geometry. Moreover, we can use a direct analysis of the action to argue that this agreement must also hold for the more general brane/antibrane configurations of hep-th/0610249. On the other hand, when our strongly coupled description is reliable, the M5 wraps a nonholomorphic minimal area curve that can exhibit quite different properties, suggesting that the residual structure remaining after spontaneous breaking of supersymmetry at tree level can be further broken by the effects of string interactions. Finally, we discuss the boundary condition issues raised in hep-th/0608157 for nonsupersymmetric IIA configurations, their implications for our setup, and their realization on the type IIB side.

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arXiv2007

A second order deconfinement transition for large N 2+1 dimensional Yang-Mills theory on a small two-sphere

We study the thermodynamics of large N pure 2+1 dimensional Yang-Mills theory on a small spatial sphere. By studying the effective action for the Polyakov loop order parameter, we show analytically that the theory has a second order deconfinement transition to a phase where the eigenvalue distribution of the Polyakov loop is non-uniform but still spread over the whole unit circle. At a higher temperature, the eigenvalue distribution develops a gap, via an additional third-order phase transition. We discuss possible forms of the full phase diagram as a function of temperature and sphere radius. Our results together with extrapolation of lattice results relevant to the large volume limit imply the existence of a critical radius in the phase diagram at which the deconfinement transition switches from second order to first order. We show that the point at the critical radius and temperature can be either a tricritical point with universal behavior or a triple point separating three distinct phases.

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arXiv2006

A first order deconfinement transition in large N Yang-Mills theory on a small 3-sphere

We give an analytic demonstration that the 3+1 dimensional large N SU(N) pure Yang-Mills theory, compactified on a small 3-sphere so that the coupling constant at the compactification scale is very small, has a first order deconfinement transition as a function of temperature. We do this by explicitly computing the relevant terms in the canonical partition function up to 3-loop order; this is necessary because the leading (1-loop) result for the phase transition is precisely on the borderline between a first order and a second order transition. Since numerical work strongly suggests that the infinite volume large N theory also has a first order deconfinement transition, we conjecture that the phase structure is independent of the size of the 3-sphere. To deal with divergences in our calculations, we are led to introduce a novel method of regularization useful for nonabelian gauge theory on a 3-sphere.

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arXiv2006

The Phase Structure of Low Dimensional Large N Gauge Theories on Tori

In this paper we continue our study of the thermodynamics of large N gauge theories on compact spaces. We consider toroidal compactifications of pure SU(N) Yang-Mills theories and of maximally supersymmetric Yang-Mills theories dimensionally reduced to 0+1 or 1+1 dimensions, and generalizations of such theories where the adjoint fields are massive. We describe the phase structure of these theories as a function of the gauge coupling, the geometry of the compact space and the mass parameters. In particular, we study the behavior of order parameters associated with the holonomy of the gauge field around the cycles of the torus. Our methods combine analytic analysis, numerical Monte Carlo simulations, and (in the maximally supersymmetric case) information from the dual gravitational theories.

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arXiv2005

S-duality and a large N phase transition in N=4 SYM on K3 at strong coupling

We study the supersymmetric partition function of {\cal N}= 4 super Yang-Mills with gauge group SU(N) on K3 in the large N, fixed g limit and show that it undergoes a first order phase transition at the S-duality invariant value of the gauge coupling g. Turning on the θ-angle we find lines of phase transitions on the τplane. The resulting phase diagram and the large N free energy are exactly SL(2,Z) invariant. Similar phase transitions take place in systems related to the {\cal N}=4 on K3 by dualities. One of them is the Dabholkar-Harvey heterotic string system. We consider its mixed (a la Ooguri-Strominger-Vafa) partition function allowing contributions from multi-string states. We find that in the large winding charge limit, it undergoes a phase transition with respect to chemical potential for momentum. It is a short-string, long-string transition that we find interesting in connection with black hole entropy counting.

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arXiv2005

Minisuperspace Quantization of "Bubbling AdS" and Free Fermion Droplets

We quantize the space of 1/2 BPS configurations of Type IIB SUGRA found by Lin, Lunin and Maldacena (hep-th/0409174), directly in supergravity. We use the Crnkovic-Witten-Zuckerman covariant quantization method to write down the expression for the symplectic structure on this entire space of solutions. We find the symplectic form explicitly around AdS_5 x S^5 and obtain a U(1) Kac-Moody algebra, in precise agreement with the quantization of a system of N free fermions in a harmonic oscillator potential, as expected from AdS/CFT. As a cross check, we also perform the quantization around AdS_5 x S^5 by another method, using the known spectrum of physical perturbations around this background and find precise agreement with our previous calculation.

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arXiv2005

The Hagedorn/Deconfinement Phase Transition in Weakly Coupled Large N Gauge Theories

We demonstrate that weakly coupled, large N, d-dimensional SU(N) gauge theories on a class of compact spatial manifolds (including S^{d-1} \times time) undergo deconfinement phase transitions at temperatures proportional to the inverse length scale of the manifold in question. The low temperature phase has a free energy of order one, and is characterized by a stringy (Hagedorn) growth in its density of states. The high temperature phase has a free energy of order N^2. These phases are separated either by a single first order transition that generically occurs below the Hagedorn temperature or by two continuous phase transitions, the first of which occurs at the Hagedorn temperature. These phase transitions could perhaps be continuously connected to the usual flat space deconfinement transition in the case of confining gauge theories, and to the Hawking-Page nucleation of AdS_5 black holes in the case of the N=4 supersymmetric Yang-Mills theory. We suggest that deconfinement transitions may generally be interpreted in terms of black hole formation in a dual string theory. Our analysis proceeds by first reducing the Yang-Mills partition function to a (0+0)-dimensional integral over a unitary matrix U, which is the holonomy (Wilson loop) of the gauge field around the thermal time circle in Euclidean space; deconfinement transitions are large N transitions in this matrix integral.

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