38 research outputs found
Isospin breaking effects in the X(3872) resonance
In this paper we study the effects of isospin breaking in the dynamical
generation of the X(3872) state. We also calculate the ratio of the branching
fractions of the decaying into with two and three pions, which has
been measured experimentally to be close to unity. Together with the X(3872),
of positive C-parity, we predict the existence of a negative C-parity state and
we comment on which decay channel is more promising to observe this state.Comment: 10 pages, 6 figures, study on the line shape of the X(3872) adde
Charm and Hidden Charm Scalar Resonances in Nuclear Matter
We study the properties of the scalar charm resonances and
, and the theoretical hidden charm state X(3700) in nuclear matter.
We find that for the and X(3700) resonances, with negligible and
small width at zero density, respectively, the width becomes about and at normal nuclear matter density, accordingly. For
the change in width is relatively less important. We discuss the
origin of this new width and trace it to reactions occurring in the nucleus. We
also propose a possible experimental test for those modifications in nuclear
matter, which will bring valuable information on the nature of those scalar
resonances and the interaction of mesons with nucleons.Comment: 3 pages, 3 figures, to appear in the proceedings of the International
Conference on Particles And Nuclei (PANIC08), Eilat, Israel, November 9-14,
200
An algorithm for network community structure determination by surprise
Graphs representing real world systems may be studied from their underlying
community structure. A community in a network is an intuitive idea for which
there is no consensus on its objective mathematical definition. The most used
metric in order to detect communities is the modularity, though many
disadvantages of this parameter have already been noticed in the literature. In
this work, we present a new approach based on a different metric: the surprise.
Moreover, the biases of different community detection algorithms and benchmark
networks are thoroughly studied, identified and commented about.Comment: 29 pages, 6 figures, 7 table
To Google or not : differences on how online searches predict names and faces
Word and face recognition are processes of interest for a large number of fields, including both clinical psychology and computer calculations. The research examined here aims to evaluate the role of an online frequency’s ability to predict both face and word recognition by examining the stability of these processes in a given amount of time. The study will further examine the differences between traditional theories and current contextual frequency approaches. Reaction times were recorded through both a logarithmic transformation and through a Bayesian approach. The Bayes factor notation was employed as an additional test to support the evidence provided by the data. Although differences between face and name recognition were found, the results suggest that latencies for both face and name recognition are stable for a period of six months and online news frequencies better predict reaction time for both classical frequentist analyses. These findings support the use of the contextual diversity approach
The small-world of 'Le Petit Prince': Revisiting the word frequency distribution
[EN] Many complex systems are naturally described through graph theory, and different
kinds of systems described as networks present certain important characteristics
in common. One of these features is the so-called scale-free distribution
for its node s connectivity, which means that the degree distribution for the
network s nodes follows a power law. Scale-free networks are usually referred
to as small-world because the average distance between their nodes do not scale
linearly with the size of the network, but logarithmically. Here we present a
mathematical analysis on linguistics: the word frequency effect for different translations
of the Le Petit Prince in different languages. Comparison of word association
networks with random networks makes evident the discrepancy between
the random Erdo¿s-Re¿ny model for graphs and real-world networks.Gamermann ., D.; Moret-Tatay, C.; Navarro Pardo, E.; Fernández De Córdoba, P. (2016). The small-world of 'Le Petit Prince': Revisiting the word frequency distribution. Digital Scholarship in the Humanities. 32(2):301-311. doi:10.1093/llc/fqw005S30131132
Large scale evaluation of differences between network-based and pairwise sequence-alignment-based methods of dendrogram reconstruction
[EN] Dendrograms are a way to represent relationships between organisms. Nowadays, these are inferred based on the comparison of genes or protein sequences by taking into account their differences and similarities. The genetic material of choice for the sequence alignments (all the genes or sets of genes) results in distinct inferred dendrograms. In this work, we evaluate differences between dendrograms reconstructed with different methodologies and for different sets of organisms chosen at random from a much larger set. A statistical analysis is performed to estimate fluctuations between the results obtained from the different methodologies that allows us to validate a systematic approach, based on the comparison of the organisms' metabolic networks for inferring dendrograms. This has the advantage that it allows the comparison of organisms very far away in the evolutionary tree even if they have no known ortholog gene in common. 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