Energy Loss of an Infinitely Massive Half-Bogomol'nyi-Prasad-Sommerfeld Particle by Radiation to All Orders in 1/N

We use the AdS/CFT correspondence to compute the energy radiated by an infinitely massive half-Bogomol'nyi-Prasad-Sommerfeld particle charged under N = 4 super Yang-Mills theory, transforming in the symmetric or antisymmetric representation of the gauge group, and moving in the vacuum, to all orders in 1 / N and for large 't Hooft coupling. For the antisymmetric case we consider D 5 -branes reaching the boundary of five-dimensional anti-de Sitter space ( AdS 5 ) at arbitrary timelike trajectories, while for the symmetric case, we consider a D 3 -brane in AdS 5 that reaches the boundary at a hyperbola. We compare our results to the one obtained for the fundamental representation, deduced by considering a string in AdS 5

Probing N=2 superconformal field theories with localization

We use supersymmetric localization to study probes of four dimensional Lagrangian N=2 superconformal field theories. We first derive a unique equation for the eigenvalue density of these theories. We observe that these theories have a Wigner eigenvalue density precisely when they satisfy a necessary condition for having a holographic dual with a sensible higher-derivative expansion. We then compute in the saddle-point approximation the vacuum expectation value of 1/2-BPS circular Wilson loops, and the two-point functions of these Wilson loops with the Lagrangian density and with the stress-energy tensor. This last computation also provides the corresponding Bremsstrahlung functions and entanglement entropies. As expected, whenever a finite fraction of the matter is in the fundamental representation, the results are drastically different from those of N=4 supersymmetric Yang-Mills theory

VLX-Stories: a semantically linked event platform for media publishers

In the recent years, video sharing in social media from different video recording devices has resulted in a exponential growth of videos on the Internet. Such video data is continuously increasing with daily recordings related to a wide number of topics. In this context, video understanding has become a critical problem to address. Video search and indexation benefits from the use of keyword tags related to the video content, but most of the shared video content does not contain these tags. Although the use of deep learning has become essential for image analysis in several areas, video domain is still a relatively unexplored field for these type of methods. On the other hand knowledge graphs as Freebase or WordNet store high quantities of information about the word and relations that can be used to disambiguate concepts and relate them through contextual information In this research project we search to explore and improve the understanding of video content through the use of automatic tagging models based on Machine Learning and Deep Learning techniques, improved by the use of knowledge bases.Peer ReviewedPostprint (published version

Enhancing online knowledge graph population with semantic knowledge

Knowledge Graphs (KG) are becoming essential to organize, represent and store the world’s knowledge, but they still rely heavily on humanly-curated structured data. Information Extraction (IE) tasks, like disambiguating entities and relations from unstructured text, are key to automate KG population. However, Natural Language Processing (NLP) methods alone can not guarantee the validity of the facts extracted and may introduce erroneous information into the KG. This work presents an end-to-end system that combines Semantic Knowledge and Validation techniques with NLP methods, to provide KG population of novel facts from clustered news events. The contributions of this paper are two-fold: First, we present a novel method for including entity-type knowledge into a Relation Extraction model, improving F1-Score over the baseline with TACRED and TypeRE datasets. Second, we increase the precision by adding data validation on top of the Relation Extraction method. These two contributions are combined in an industrial pipeline for automatic KG population over aggregated news, demonstrating increased data validity when performing online learning from unstructured web data. Finally, the TypeRE and AggregatedNewsRE datasets build to benchmark these results are also published to foster future research in this field.This work was partially supported by the Government of Catalonia under the industrial doctorate 2017 DI 011.Peer ReviewedPostprint (author's final draft

Exact results for static and radiative fields of a quark in N=4 super Yang-Mills

In this work (which supersedes our previous preprint arXiv:1112.2345) we determine the expectation value of the N=4$ SU(N) SYM Lagrangian density operator in the presence of an infinitely heavy static particle in the symmetric representation of SU(N), by means of a D3-brane probe computation. The result that we obtain coincides with two previous computations of different observables, up to kinematical factors. We argue that these agreements go beyond the D-brane probe approximation, which leads us to propose an exact formula for the expectation value of various operators. In particular, we provide an expression for the total energy loss by radiation of a heavy particle in the fundamental representation.Comment: 14 pages. This submission supersedes our previous preprint arXiv:1112.2345. v2: numerical factors fixed, minor clarifications, added reference