Bridging over p-wave pi-production and weak processes in few-nucleon systems with chiral perturbation theory

I study an aspect of chiral perturbation theory (\chi PT) which enables one to ``bridge'' different reactions. That is, an operator fixed in one of the reactions can then be used to predict the other. For this purpose, I calculate the partial wave amplitude for the p-wave pion production (pp\to pn\pi^+) using the pion production operator from the lowest and the next nonvanishing orders. The operator includes a contact operator whose coupling has been fixed using a matrix element of a low-energy weak process (pp\to de^+\nu_e). I find that this operator does not reproduce the partial wave amplitude extracted from experimental data, showing that the bridging over the reactions with significantly different kinematics is not necessarily successful. I study the dependence of the amplitude on the various inputs such as the NN potential, the \pi N\Delta coupling, and the cutoff. I argue the importance of a higher order calculation. In order to gain an insight into a higher order calculation, I add a higher order counter term to the operator used above, and fit the couplings to both the low-energy weak process and the pion production. The energy dependence of the partial wave amplitude for the pion production is described by the operator consistently with the data. However, I find a result which tells us to be careful about the convergence of the chiral expansion for the pp\to pn\pi^+ reaction.Comment: 30 pages, 13 figures, figures changed, compacted tex

Computing Trees of Named Word Usages from a Crowdsourced Lexical Network

Thanks to the participation of a large number of persons via web-based games, a large-sized evolutionary lexical network is available for French. With this resource, we tackled the question of the determination of the word usages of a term, and then we introduced the notion of similarity between these various word usages. So, for a given term, we were able to build its word usage tree: the root groups together all its possible usages and a search in the tree corresponds to a refinement of these word usages. The labelling of the various nodes of the word usage tree of a term is made during a breadth-first search: the root is labelled by the term itself and each node of the tree is labelled by a term stemming from the clique or quasi-clique this node represents. We show on a precise example that it is possible that some nodes of the tree, often leaves, cannot be labelled without ambiguity. This paper ends with an evaluation about word usages detected in our lexical network.

PP Attachment Ambiguity Resolution with Corpus-Based Pattern Distributions and Lexical Signatures

Invited PaperInternational audienceIn this paper, we propose a method combining unsupervised learning of lexical frequencies with semantic information aiming at improving PP attachment ambiguity resolution. Using the output of a robust parser, i.e. the set of all possible attachments for a given sentence, we query the Web and obtain statistical information about the frequencies of the attachments distributions as well as lexical signatures of the terms on the patterns. All this information is used to weight the dependencies yielded by the parser

Modelling, Detection And Exploitation Of Lexical Functions For Analysis.

Lexical functions (LF) model relations between terms in the lexicon. These relations can be knowledge about the world (Napoleon was an emperor) or knowledge about the language (‘destiny’ is synonym of ‘fate’)

Lexical Functions For Ants Based Semantic Analysis.

Semantic analysis (SA) is a central operation in natural language processing. We can consider it as the resolution of 5 problems: lexical ambiguity, references, prepositional attachments, interpretative paths and lexical functions instanciation

Multilingual Knowledge Base Completion by Cross-lingual Semantic Relation Inference

International audienceIn the present paper, we propose a simple en-dogenous method for enhancing a multilingual knowledge base through the cross-lingual semantic relation inference. It can be run on multilingual resources prior to semantic representation learning. Multilingual knowledge bases may integrate preexisting structured resources available for resource-rich languages. We aim at performing cross-lingual inference on them to improve the low resource language by creating semantic relationships

Conceptual Vectors, A Complementary Tool To Lexical Networks.

There is currently much research in natural language processing focusing on lexical networks. Most of them, in particular the most famous, word-Net, lack syntagmatic information and especially thematic information (“Tennis Problem"). This article describes conceptual vectors that allows the representation of ideas in any textual segment and offers a continuous vision of related thematics, based on the distances between these thematics. We show the characteristics of conceptual vectors and explain how they complement lexico-semantic networks. we illustrate this purpose by adding conceptual vectors to wordNet by emergence

Vectorisation paramétrée des données textuelles

International audienceAutomatic processing of textual data enables users to analyze semi-automatically and on a large scale the data. This analysis is based on two successive processes: (i) representation of texts, (ii) gathering of textual data (clustering). The software described in this paper focuses on the first step of the process by offering expert a parameterized representation of textual data