Balseiro Institute

About: Balseiro Institute is a education organization based out in Bariloche, Argentina. It is known for research contribution in the topics: Magnetization & Superconductivity. The organization has 1133 authors who have published 2624 publications receiving 49970 citations.

Towards a derivation of holographic entanglement entropy

Abstract: We provide a derivation of holographic entanglement entropy for spherical entangling surfaces. Our construction relies on conformally mapping the boundary CFT to a hyperbolic geometry and observing that the vacuum state is mapped to a thermal state in the latter geometry. Hence the conformal transformation maps the entanglement entropy to the thermodynamic entropy of this thermal state. The AdS/CFT dictionary allows us to calculate this thermodynamic entropy as the horizon entropy of a certain topological black hole. In even dimensions, we also demonstrate that the universal contribution to the entanglement entropy is given by A-type trace anomaly for any CFT, without reference to holography.

D-Branes at Singularities : A Bottom-Up Approach to the String Embedding of the Standard Model

Abstract: We propose a bottom-up approach to the building of particle physics models from string theory. Our building blocks are Type II D-branes which we combine appropriately to reproduce desirable features of a particle theory model: 1) Chirality ; 2) Standard Model group ; 3) N =1 orN = 0 supersymmetry ; 4) Three quark-lepton generations. We start such a program by studying congurations of D = 10, Type IIB D3-branes located at singularities. We study in detail the case of ZZN N =1 ; 0 orbifold singularities leading to the SM group or some left-right symmetric extension. In general, tadpole cancellation conditions require the presence of additional branes, e.g. D7-branes. For the N =1s upersymmetric case the unique twist leading to three quark-lepton generations is ZZ3, predicting sin 2 W =3 =14 = 0:21. The models obtained are the simplest semirealistic string models ever built. In the non-supersymmetric case there is a three-generation model for each ZZN, N> 4, but the Weinberg angle is in general too small. One can obtain a large class of D =4 compact models by considering the above structure embedded into a Calabi Yau compactication. We explicitly construct examples of such compact models using ZZ3 toroidal orbifolds and orientifolds, and discuss their properties. In these examples, global cancellation of RR charge may be achieved by adding anti-branes stuck at the xed points, leading to models with hidden sector gravity-induced supersymmetry breaking. More general frameworks, like F-theory compactications, allow completely N = 1 supersymmetric embeddings of our local structures, as we show in an explicit example.

Social games in a social network

Abstract: We study an evolutionary version of the Prisoner's Dilemma game, played by agents placed in a small-world network. Agents are able to change their strategy, imitating that of the most successful neighbor. We observe that different topologies, ranging from regular lattices to random graphs, produce a variety of emergent behaviors. This is a contribution towards the study of social phenomena and transitions governed by the topology of the community.

Distinguishing noise from chaos.

Abstract: Chaotic systems share with stochastic processes several properties that make them almost undistinguishable. In this communication we introduce a representation space, to be called the complexity-entropy causality plane. Its horizontal and vertical axis are suitable functionals of the pertinent probability distribution, namely, the entropy of the system and an appropriate statistical complexity measure, respectively. These two functionals are evaluated using the Bandt-Pompe recipe to assign a probability distribution function to the time series generated by the system. Several well-known model-generated time series, usually regarded as being of either stochastic or chaotic nature, are analyzed so as to illustrate the approach. The main achievement of this communication is the possibility of clearly distinguishing between them in our representation space, something that is rather difficult otherwise.

Small World Effect in an Epidemiological Model

Abstract: A model for the spread of an infection is analyzed for different population structures. The interactions within the population are described by small world networks, ranging from ordered lattices to random graphs. For the more ordered systems, there is a fluctuating endemic state of low infection. At a finite value of the disorder of the network, we find a transition to self-sustained oscillations in the size of the infected subpopulation.