1,721,161 research outputs found
Phenomena Beyond the Standard Model: What do we expect for New Physics to look like?
No full textThis eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contac
Generalized Holographic Principle, Gauge Invariance and the Emergence of Gravity à la Wilczek
Full text linkWe show that a generalized version of the holographic principle can be derived from the Hamiltonian description of information flow within a quantum system that maintains a separable state. We then show that this generalized holographic principle entails a general principle of gauge invariance. When this is realized in an ambient Lorentzian space-time, gauge invariance under the Poincaré group is immediately achieved. We apply this pathway to retrieve the action of gravity. The latter is cast à la Wilczek through a similar formulation derived by MacDowell and Mansouri, which involves the representation theory of the Lie groups SO (Formula presented.) and SO (Formula presented.)
Explorando física nova num modelo com três dubletos de Higgs e fermiões do tipo vetorial
Full text linkThe success of the Standard model (SM) can not be understated, however, the
existence of both theoretical questions as well as experimental observations without
an answer in the SM favours the study of New Physics theories. In this thesis, a
new model featuring three Higgs doublets and vector-like fermions is presented.
It is based upon a supersymmetric Grand Unified Theory where all fundamental
interactions described by the SM gauge group G = SU(3) C× SU(2) L× U(1) Y
as well as the observed flavour structure in nature are ultimately unified under the
E 8 symmetry group. The supersymmetric high-energy limit of this theory is provided
in order to motivate the various parameter choices and mass scales involved in the
numerical studies. The low-energy effective limit of this model is constructed to be
invariant under the transformations of the gauge group G. Besides new scalars and
three generations of vector-like fermions, the model also provides a rich neutrino
sector, with twelve new states, where the lightest one is sterile. In this thesis, and
using deep learning techniques, we perform the first phenomenological analysis of
this model focusing on the study of new charged vector-like leptons (VLLs) and
their possible signatures at CERN’s Large Hadron Collider (LHC). In our numerical
analysis, we consider signal events for vector-boson fusion and VLL pair production
topologies, both involving a final state containing a pair of charged leptons and two
sterile neutrinos that act as missing energy. For the SM background processes we
consider the quantum chromodynamics (QCD) (t t¯) and the W+W− fusion events.
Monte Carlo simulations are performed for LHC proton-proton collisions at a total
centre of mass energy √s = 14 TeV. All calculated observables are provided as
data sets for deep learning analysis, where a neural network with 5 layers (1 input
+ 3 hidden + 1 output) is constructed. The neural network successfully separates
background from signal events with approximately 100% accuracy and where a
boosted decision tree (BDT) is implemented in order to offer a better identification
of the different types of background and signal. Taking into account the effect of
both analysed topologies, the maximal combined significance for the observation
of new VLLs at the LHC is of 13.62 σ if their mass is 200 GeV, becoming smaller than 2
σ if the lightest VLL mass is beyond 1 TeV. The results obtained show
that our model can be tested at future LHC runs and, in particular, constraining
the energy scale for which new gauge symmetries emergent from the unification
picture can be manifest.O sucesso do Modelo Padrão (MP) não deve ser substimado, no entanto, a existência tanto de questões teóricas como de observações experiementais sem resposta no MP favorecem o estudo de teorias com Nova Física. Nesta tese um novo modelo contendo três dubletos de Higgs e fermiões do tipo vetorial é apresentado. Este é baseado em princípios de grande unificação supersimétrica e, em particular, inspirado pela unificação das interações fundamentais sob o grupo de simetria E 8, que contem o grupo de gauge do MP, G = SU(3) C × SU(2) L × U(1) Y . O limite supersimétrico de alta energia é apresentado de modo a contextualizar e justificar as escolhas de parâmetros e escalas de massa envolvidas nos estudos numéricos. O limite de baixas energia deste modelo é construído de forma a ser invariante sob transformações do grupo de gauge G. Além de novos escalares e três gerações de fermiões do tipo vetorial, o modelo também oferece um vasto setor de neutrinos com doze novos estados, sendo o mais leve estéril. Nesta tese, e recorrendo a métodos baseados em aprendizagem profunda, apresentamos a primeira análise fenomenológica deste modelo focando-nos no estudo de novos leptões carregados (do tipo vetorial) e suas possíveis assinaturas no grande colisor de protões do CERN, o LHC. A nossa análise numérica considera eventos de sinal para topologias de fusão de bosões vetoriais e topologias associadas `a produção de pares de leptões do tipo vetorial, ambas envolvendo um estado final contendo um par de leptões carregados bem como dois neutrinos estéreis que atuam como energia em falta. Para processos de fundo do MP consideramos eventos de cromodinâmica quântica (CDQ) ( t t¯) e eventos de fusão ( W + W −). As simulações de Monte Carlo são realizadas para colisões protão-protão como no LHC, a uma energia de centro de massa √ s = 14 TeV. Todas as observáveis calculadas são fornecidas para análise de aprendizagem profunda, onde uma rede neural com 5 camadas (1 entrada + 3 escondidas + 1 saída) é construída. A rede neural separa com sucesso eventos de fundo de eventos de sinal com uma precisão de quase 100% e uma ´arvore de decisão aprimorada (ADA) é implementada de modo a proporcionar uma melhor identificação dos diferentes tipos de fundo e de sinal. Tendo em conta as duas topologias analisadas, a significância máxima combinada para a observação de novos leptões do tipo vetorial no LHC ´e de 13.62σ se a sua massa for de 200 GeV, decaindo a mesma para valores inferiores a 2 σ se a massa destes estiver acima de 1 TeV. Os resultados obtidos oferecem a possibilidade de testar o modelo em futuras runs do LHC e, em particular, constranger a escala de energia à qual novas simetrias de gauge emergentes do cenário de Unificação se poderão manifestar.Mestrado em Engenharia Físic
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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