2.6k citations
Counting papers with at most 25 authors, so collaboration author lists do not stand in for the people here.
- Instituto Superior TécnicoPT388 papers
- Centro de Física Teórica de Partículas54 papers
- University of ViennaAT37 papers
- Centre National de la Recherche ScientifiqueFR34 papers
- University of LisbonPT34 papers
- University of MississippiUS31 papers
- Universitat de ValènciaES27 papers
- California Institute of TechnologyUS25 papers
- University of CoimbraPT19 papers
- European Organization for Nuclear ResearchCH18 papers
- Instituto de TelecomunicaçõesPT18 papers
- Instituto Politécnico de LisboaPT17 papers
21 papers · 1 filter
Swarms on Continuous Data
Vitorino Ramos, Ajith Abraham
While being it extremely important, many Exploratory Data Analysis (EDA) systems have the inhability to perform classification and visualization in a continuous basis or to self-or…
Web Usage Mining Using Artificial Ant Colony Clustering and Genetic Programming
Ajith Abraham, Vitorino Ramos
The rapid e-commerce growth has made both business community and customers face a new situation. Due to intense competition on one hand and the customer's option to choose from sev…
Global embedding of D-dimensional black holes with a cosmological constant in Minkowskian spacetimes: Matching between Hawking temperature and Unruh temperature
Nuno Loureiro Santos, Oscar J. C. Dias, José P. S. Lemos
We study the matching between the Hawking temperature of a large class of static D-dimensional black holes and the Unruh temperature of the corresponding higher dimensional Rindler…
New instability for rotating black branes and strings
Vitor Cardoso, José P. S. Lemos
The evolution of small perturbations around rotating black branes and strings, which are low energy solutions of string theory, are investigated. For simplicity, we concentrate on…
On a model with two zeros in the neutrino mass matrix
W. Grimus, L. Lavoura
We consider a Majorana neutrino mass matrix with , in the basis where the charged-lepton mass matrix is diagonal. W…
Zeros of the inverted neutrino mass matrix
L. Lavoura
I investigate viable textures with two texture zeros for the inverted neutrino mass matrix, and present the predictions of those textures for the neutrino masses and for lepton mix…
On the Classification of Asymptotic Quasinormal Frequencies for d-Dimensional Black Holes and Quantum Gravity
Jose Natario, Ricardo Schiappa
We provide a complete classification of asymptotic quasinormal frequencies for static, spherically symmetric black hole spacetimes in d dimensions. This includes all possible types…
Quasinormal modes and stability of the rotating acoustic black hole: numerical analysis
Vitor Cardoso, Jose' P. S. Lemos, Shijun Yoshida
The study of the quasinormal modes (QNMs) of the 2+1 dimensional rotating draining bathtub acoustic black hole, the closest analogue found so far to the Kerr black hole, is perform…
Softly broken lepton number L_e - L_μ- L_τwith non-maximal solar neutrino mixing
W. Grimus, L. Lavoura
We consider the most general neutrino mass matrix which leads to , and present the formulae needed for obtaining the neutrino masses and mixing parameters in that case.…
Renormalization of the neutrino mass operators in the multi-Higgs-doublet Standard Model
W. Grimus, L. Lavoura
We derive the renormalization group equations (RGE) for the flavour coupling matrices of the effective dimension-five operators which yield Majorana neutrino masses in the multi-Hi…
Nonholonomic Clifford Structures and Noncommutative Riemann--Finsler Geometry
Sergiu I. Vacaru
We survey the geometry of Lagrange and Finsler spaces and discuss the issues related to the definition of curvature of nonholonomic manifolds enabled with nonlinear connection stru…
Non-vanishing and from a broken symmetry
Walter Grimus, Anjan S. Joshipura, Satoru Kaneko +3
It is shown that the neutrino mass matrices in the flavour basis yielding a vanishing are characterized by invariance under a class of symmetries. A specific i…
Multifrequency analysis of 21 cm fluctuations from the Era of Reionization
M. G. Santos, A. Cooray, L. Knox
We study the prospects for extracting detailed statistical properties of the neutral Hydrogen distribution during the era of reionization using the brightness temperature fluctuati…
Lepton mixing angle with a horizontal symmetry
W. Grimus, A. S. Joshipura, S. Kaneko +2
We discuss a model for the lepton sector based on the seesaw mechanism and on a family symmetry. The model predicts the mixing angle to vanish. The solar mixing angl…
Some consequences of a noncommutative space-time structure
Rui Vilela Mendes
The existence of a fundamental length (or fundamental time) has been conjecture in many contexts. Here one discusses some consequences of a fundamental constant of this type, which…
Models of maximal atmospheric neutrino mixing and leptogenesis
W. Grimus, L. Lavoura
We discuss two extensions of the Standard Model based on the seesaw mechanism and on non-abelian family symmetry groups O(2) and , respectively. Both models have a twofold-deg…
Symmetry realization of texture zeros
W. Grimus, A. S. Joshipura, L. Lavoura +1
We show that it is possible to enforce texture zeros in arbitrary entries of the fermion mass matrices by means of Abelian symmetries; in this way, many popular mass-matrix texture…
A lower bound to the spectral threshold in curved tubes
P. Exner, P. Freitas, D. Krejcirik
We consider the Laplacian in curved tubes of arbitrary cross-section rotating together with the Frenet frame along curves in Euclidean spaces of arbitrary dimension, subject to Dir…
Spectroscopic Observations and Analysis of the Peculiar SN 1999aa
G. Garavini, G. Folatelli, A. Goobar +55
We present an extensive new time-series of spectroscopic data of the peculiar SN 1999aa in NGC 2595. Our data set includes 25 optical spectra between -11 and +58 days with respect…
Complex Behavior of Stock Markets: Processes of Synchronization and Desynchronization during Crises
Tanya Araújo, Francisco Louçã
This paper investigates the dynamics of in the S&P500 index from daily returns for the last 30 years. Using a stochastic geometry technique, each S&P500 yearly batch of data is emb…
Extension of the Buchalla-Safir bound
L. Lavoura
I provide a simple derivation of the Buchalla-Safir bound on gamma. I generalize it to the case where an upper bound on the phase of the penguin pollution is assumed. I apply the B…