arXiv subjects

Carlos Nunez

Publications and source records attributed to Carlos Nunez.

99 records · Page 6Linked to original sources

arXiv2001

Supergravity duals of gauge theories from F(4) gauged supergravity in six dimensions

We construct supergravity solutions dual to twisted field theories that are the worldvolume theories of D4-branes wrapped on 2, 3-cycles, and NS-fivebranes on 3-cycles. We first obtain the solutions for the Romans' six-dimensional gauged supergravity theories and then up-lift them to ten dimensions. In particular, we find solutions for field configurations with either non-Abelian fields or B-fields being excited. One of these solutions, in the massless case, is up-lifted to the massless type IIA string theory. This is the first example of such a kind. The cases studied provide new examples of the AdS/CFT duality involving twisted field theories.

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arXiv2001

Brane Worlds, String Cosmology, and AdS/CFT

Using the thin-shell formalism we discuss the motion of domain walls in de Sitter and anti-de Sitter (AdS) time-dependent bulks. This motion results in a dynamics for the brane scale factor. We show that in the case of a clean brane the scale factor describes both singular and non-singular universes, with phases of contraction and expansion. These phases can be understood as quotients of AdS spacetime by a discrete symmetry group. We discuss this effect in some detail, and suggest how the AdS/CFT correspondence could be applied to obtain a non perturbative description of brane-world string cosmology.

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arXiv2001

D6 branes and M theory geometrical transitions from gauged supergravity

We study the supergravity duals of supersymmetric theories arising in the world-volume of D6 branes wrapping holomorphic two-cycles and special Lagrangian three-cycles within the framework of eight dimensional gauged supergravity. When uplifted to 11d, our solutions represent M-theory on the background of, respectively, the small resolution of the conifold and a manifold with G_2 holonomy. We further discuss on the flop and other possible geometrical transitions and its implications.

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arXiv2000

Towards the large N limit of pure N=1 super Yang Mills

We find the gravity solution corresponding to a large number of NS or D fivebranes wrapped on a two sphere so that we have pure ${\cal N}=1$ super Yang-Mills in the IR. The supergravity solution is smooth, it shows confinement and it breaks the $U(1)_R$ chiral symmetry in the appropriate way. When the gravity approximation is valid the masses of glueballs are comparable to the masses of Kaluza Klein states on the fivebrane, but if we could quantize strings on this background it looks like we should be able to decouple the KK states.

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arXiv2000

Quantum Cosmology and AdS/CFT

In this paper we study the creation of brane-worlds in $AdS$ bulk. We first consider the simplest case of onebranes in $AdS_3$. In this case we are able to properly describe the creation of a spherically symmetric brane-world deriving a general expression for its wavefunction. Then, we sketch the $AdS_{d+1}$ set-up within the context of the WKB approximation. Finally, we comment on these scenarios in light of the $AdS/CFT$ correspondence.

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arXiv2000

Supergravity description of field theories on curved manifolds and a no go theorem

In the first part of this paper we find supergravity solutions corresponding to branes on worldvolumes of the form $R^d \times Σ$ where $Σ$ is a Riemann surface. These theories arise when we wrap branes on holomorphic Riemann surfaces inside $K3$ or CY manifolds. In some cases the theory at low energies is a conformal field theory with two less dimensions. We find some non-singular supersymmetric compactifications of M-theory down to $AdS_5$. We also propose a criterion for permissible singularities in supergravity solutions. In the second part of this paper, which can be read independently of the first, we show that there are no non-singular Randall-Sundrum or de-Sitter compactifications for large class of gravity theories.

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arXiv2000

From Noncommutative Bosonization to S-Duality

We extend standard path-integral techniques of bosonization and duality to the setting of noncommutative geometry. We start by constructing the bosonization prescription for a free Dirac fermion living in the noncommutative plane R_θ^2. We show that in this abelian situation the fermion theory is dual to a noncommutative Wess-Zumino-Witten model. The non-abelian situation is also constructed along very similar lines. We apply the techniques derived to the massive Thirring model on noncommutative R_θ^2 and show that it is dualized to a noncommutative WZW model plus a noncommutative cosine potential (like in the noncommutative Sine-Gordon model). The coupling constants in the fermionic and bosonic models are related via strong-weak coupling duality. This is thus an explicit construction of S-duality in a noncommutative field theory.

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arXiv1997

Supersymmetry and Bosonization in Three Dimensions

We discuss on the possible existence of a supersymmetric invariance in purely fermionic planar systems and its relation to the fermion-boson mapping in three-dimensional quantum field theory. We consider, as a very simple example, the bosonization of free massive fermions and show that, under certain conditions on the masses, this model displays a supersymmetric-like invariance in the low energy regime. We construct the purely fermionic expression for the supercurrent and the non-linear supersymmetry transformation laws. We argue that the supersymmetry is absent in the limit of massless fermions where the bosonized theory is non-local.

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arXiv1996

Supersymmetric Electroweak Cosmic Strings

We study the connection between $N=2$ supersymmetry and a topological bound in a two-Higgs-doublet system with an $SU(2)\times U(1)_Y\times U(1)_{Y^{\prime}}$ gauge group. We derive the Bogomol'nyi equations from supersymmetry considerations showing that they hold provided certain conditions on the coupling constants, which are a consequence of the huge symmetry of the theory, are satisfied. Their solutions, which can be interpreted as electroweak cosmic strings breaking one half of the supersymmetries of the theory, are studied. Certain interesting limiting cases of our model which have recently been considered in the literature are finally analyzed.

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