Antonio Segui

N = 2 Supersymmetric Black Attractors in Six and Seven Dimensions

Using a quaternionic formulation of the moduli space M (IIA/K3) of 10D type IIA superstring on a generic K3 complex surface with volume V 0, we study extremal N = 2 black attractors in 6D space-time and their uplifting to 7D. For the 6D theory, we exhibit the role played by 6D N = 1 hypermultiplets and the Z m central charges isotriplet of the 6D N = 2 superalgebra. We construct explicitly the special hyperKahler geometry of M (IIA/K3) and show that the SO(4)×SO(20)

On heat properties of AdS black holes in higher dimensions

A bstractWe investigate the heat properties of AdS Black Holes in higher dimensions. We consider the study of the corresponding thermodynamical properties including the heat capacity explored in the determination of the black hole stability. In particular, we compute the heat latent. To overcome the instability problem, the Maxwell construction, in the (T, S)-plane, is elaborated. This method is used to modify the the Hawking-Page phase structure by removing the negative heat capacity regions. Then, we discuss the thermodynamic cycle and the heat engines using the way based on the extraction of the work from a black hole solution.

The Supermembrane with Central Charges on a G2 Manifold

We construct an 11D supermembrane with topological central charges induced through an irreducible winding on a G2 manifold realized from the T7/Z32 orbifold construction. The Hamiltonian H of the theory on a T7 target has a discrete spectrum. Within the discrete symmetries of H associated with large diffeomorphisms, the Z2 × Z2 × Z2 group of automorphisms of the quaternionic subspaces preserving the octonionic structure is relevant. By performing the corresponding identification on the target space, the supermembrane may be formulated on a G2 manifold, preserving the discreteness of its supersymmetric spectrum. The corresponding 4D low energy effective field theory has N = 1 supersymmetry.

Entropy of pairs of dual attractors in six and seven dimensions

We study the attractor mechanism of dual pairs of black brane bounds in = 2 supergravity in six and seven dimensions. First, we consider the effective potentials of the 6D and 7D black branes as well as their entropies. The contribution coming from the SO(1,1) factor of the moduli spaces M6D and M7D of these theories is carefully analyzed and it is used to motivate the study of the dual black branes bounds; which in turn allow to fix the critical value of the dilaton at horizon. The attractor eqs. of the black branes and the bound pairs are derived by combining the criticality conditions of the corresponding effective potentials and the Lagrange multiplier method capturing constraints eqs. on the fields moduli.

ON F-THEORY QUIVER MODELS AND KAC–MOODY ALGEBRAS

We discuss quiver gauge models with bi-fundamental and fundamental matter obtained from F-theory compactified on ALE spaces over a four-dimensional base space. We focus on the base geometry which consists of intersecting F0 = CP1 × CP1 Hirzebruch complex surfaces arranged as Dynkin graphs classified by three kinds of Kac–Moody (KM) algebras: ordinary, i.e. finite-dimensional, affine and indefinite, in particular hyperbolic. We interpret the equations defining these three classes of generalized Lie algebras as the anomaly cancelation condition of the corresponding N = 1 F-theory quivers in four dimensions. We analyze in some detail hyperbolic geometries obtained from the affine base geometry by adding a node, and we find that it can be used to incorporate fundamental fields to a product of SU-type gauge groups and fields.

On Local F-theory Geometries and Intersecting D7-branes

We discuss local F-theory geometries and their gauge theory dualities in terms of intersecting D7-branes wrapped four-cycles in Type IIB superstring. The manifolds are built as elliptic K3 surface fibrations over intersecting F0 = CP1 × CP1 base geometry according to ADE Dynkin Diagrams. The base is obtained by blowing up the extended ADE hyper-Kahler singularities of eight-dimensional manifolds considered as sigma model target spaces with eight supercharges. The resulting gauge theory of such local F-theory models are given in terms of Type IIB D7-branes wrapped intersecting F0. The four-dimensional N = 1 anomaly cancelation requirement translates into a condition on the associated affine Lie algebras.

Generalized Nariai Solutions for Yang-type Monopoles

A detailed study of the geometries that emerge by a gravitating generalized Yang monopole in even dimensions is carried out, in particular, those which present black hole and cosmological horizons. This two-horizon system is thermally unstable. The process of thermalization will drive both horizons to coalesce. This limit is what is profusely studied in this paper. It is shown that even though coordinate distance shrinks to zero, physical distance does not. So, there is some remaining space whose geometry has been computed and identified as a generalized Nariai solution. The thermal properties of this new spacetime are then calculated. Topics such as the elliptical relation between radii of spheres in the geometry or a discussion about whether a mass-type term should be present in the line element or not are also included.

Engineering of Quantum Hall Effect from Type IIA String Theory on The K3 Surface

Using D-brane configurations on the K3 surface, we give six-dimensional type IIA stringy realizations of the Quantum Hall Effect (QHE) in 1+2 dimensions. Based on the vertical and horizontal lines of the K3 Hodge diamond, we engineer two different stringy realizations. The vertical line presents a realization in terms of D2 and D6-branes wrapping the K3 surface. The horizontal one is associated with hierarchical stringy descriptions obtained from a quiver gauge theory living on a stack of D4-branes wrapping intersecting 2-spheres embedded in the K3 surface with deformed singularities. These geometries are classified by three kinds of the Kac–Moody algebras: ordinary, i.e. finite dimensional, affine and indefinite. We find that no stringy QHE in 1+2 dimensions can occur in the quiver gauge theory living on intersecting 2-spheres arranged as affine Dynkin diagrams. Stringy realizations of QHE can be done only for the finite and indefinite geometries. In particular, the finite Lie algebras give models with fractional filling fractions, while the indefinite ones classify models with negative filling fractions which can be associated with the physics of holes in the graphene.

On Brane inflation potentials and black hole attractors

We propose a new potential in brane inflation theory, which is given by the arctangent of the square of the scalar field. Then we perform an explicit computation for inflationary quantities. This potential has many nice features. In the small field approximation, it reproduces the chaotic and MSSM potentials. It allows one, in the large field approximation, to implement the attractor mechanism for bulk black holes where the geometry on the brane is de Sitter. In particular, we show, up to some assumptions, that the Friedman equation can be reinterpreted as a Schwarzschild black hole attractor equation for its mass parameter.

Graph Theory and Qubit Information Systems of Extremal Black Branes

Using graph theory based on Adinkras, we reconsider the study of extremal black branes in the framework of quantum information. More precisely, we propose a one-to-one correspondence between qubit systems, Adinkras and certain extremal black branes obtained from a type IIA superstring compactified on T n. We accordingly interpret the real Hodge diagram of T n as the geometry of a class of Adinkras formed by bosonic nodes representing n qubits. In this graphic representation, each node encodes information on the qubit quantum states and the charges of the extremal black branes built on T n. The correspondence is generalized to n superqubits associated with odd and even geometries on the real supermanifold . Using a combinatorial computation, general expressions describing the number of the bosonic and the fermionic states are obtained.