New frequencies and geometries for plasmonics and metamaterials

The manipulation of light at the nanoscale has become a fascinating research field called nanophotonics. It brings together a wide range of topics such as semiconductor quantum dots or molecular optoelectronics and the study of metal optics, or plasmonics, on one hand and the development of finely designed structures with specifically engineered optical properties called metamaterials on the other. As is often the case, it is at the boundary of these two domains that most novel effects can be observed. Plasmonics has for instance enabled the detection of single molecules due to the large field enhancement which exists in the vicinity of nanostructured metals. Thanks to the confinement of electromagnetic waves below the diffraction limit plasmonic systems are also foreseen as ideal conduits connecting electronic and photonic systems. On another hand, when a material is patterned on a scale smaller than the wavelength, its optical properties are reflections of the structure of the patterned material rather than the material itself, a concept known as metamaterial. This has allowed researchers to obtain exotic optical properties such as negative refractive indices and can be implemented in devices acting like invisibility cloaks or perfect lenses. While the prospects for nanophotonics are far-reaching, real-life applications are severely limited by the intrinsic absorption of metals and the current fabrication methods mostly based on electron-beam lithography which is slow and costly. In this thesis, we investigate these issues by considering the potentials of other polaritonic materials such as semiconductors, silicon carbide and graphene for field confinement applications. This is achieved through the combination of both numerical studies and sample fabrication and testing with the help of international collaborators. Our results show much improvement over the metallic structures typically used, with an operating range covering the near- and mid-infrared as well as the terahertz. The field compression can also be much greater compared to conventional plasmonic materials, with near-field enhancements reaching four orders of magnitude. Furthermore, we analyse theoretically the optical properties of metallic gyroids which are obtained by self-assembly - a promising chemical route for fabricating large-scale 3D structures with molecular sized resolution. These materials exhibit unexpected properties such as negative refraction and could in consequence be used as thin lenses or wave-plates. Last, we develop and apply a theoretical formulation of Fano theory for the case of plasmonics. It allows a clear and simple physical understanding of the interference spectra which are commonly encountered in nanooptics.Open Acces

Pesquisa cirúrgica no norte e nordeste do Brasil

PURPOSE: To evaluate the scientific production from the surgical areas from the State University of Para (UEPA), Federal Universities of Para (UFPA) and of Paraiba (UFPB), Brazil. METHODS: The scientific productions of professors in the last five years were classified according to the Qualis system of CAPES-Medicine III (http://qualis.capes.gov.br/webqualis/publico/pesquisaPublicaClassificacao.seam?conversationPropagation=begin) and it was computed the number of guidance of students scientific projects. RESULTS: Seventy-four professors were included, 31 with Master and 43 with PhD degrees. UFPA presented more publications (49% out of the total), which 32% of them in Journals B1 or higher. Otorhinolaryngology presented the greatest number of publications (29% out of the total); however, 98% of them in B3 or lower. Gastroenterological Surgery, which is responsible for 23% out of the total, had 57% of its publications in B1 or higher. The most frequent type of guidance was the one about scientific work of completion of undergraduate course (63%). Gynecology and Obstetrics presented the greatest number of student's guidance (35% out of the total) and Gastroenterological Surgery the largest number of Master's degree and PhD degree supervisions. CONCLUSIONS: The specialties Gynecology and Obstetrics and Gastroenterological Surgery from the State University of Para (UEPA), Federal Universities of Para (UFPA) and of Paraiba (UFPB) presented the greatest number of professors with academic degrees. Gastroenterological Surgery presented the largest scientific productions at higher strata of WebQualis CAPES classification and also the largest number of Master and PhD directed.OBJETIVO: Avaliar titulação e produção de docentes da área cirúrgica das Universidades Estadual do Pará (UEPA), Federal do Pará (UFPA) e Federal da Paraíba (UFPB). MÉTODOS: A produção dos docentes nos últimos cinco anos foi classificada segundo o Qualis da Medicina III da CAPES (http://qualis.capes.gov.br/webqualis/publico/pesquisaPublicaClassificacao.seam?conversationPropagation=begin), e computou-se o número de orientações concluídas. RESULTADOS: Foram incluídos 74 docentes, 31 mestres e 43 doutores. A UFPA apresentou maior produção científica (49% do total de publicações), com 32% destas em periódicos Qualis B1 ou superior. A especialidade com maior número de publicações foi a Otorrinolaringologia (29% do total); entretanto, 98% destas em Qualis B3 ou inferior. Já a Cirurgia Gastroenterológica, responsável por 23% do total, teve 57% de suas publicações em Qualis B1 ou superior. O tipo mais frequente de orientação foi a de trabalhos de conclusão de cursos de graduação (63%). Ginecologia e Obstetrícia apresentou o maior número de orientações concluídas (35% do total), e Cirurgia Gastroenterológica o maior número de orientações de mestrado e doutorado. CONCLUSÕES: As especialidades Ginecologia e Obstetrícia e Cirurgia Gastroenterológica apresentaram o maior número de docentes titulados. A Cirurgia Gastroenterológica apresentou a maior produção nos extratos do Qualis-CAPES, e também o maior número de orientações concluídas de mestrado e doutorado.UEPA Medical SchoolUFPA Medical SchoolUFPB Medical SchoolUNIFESP Plastic Surgery DivisionUNIVÁS Plastic Surgery DivisionUNIFESP Head of Plastic Surgery Division CAPESUNIFESP, Plastic Surgery DivisionUNIFESP, Head of Plastic Surgery Division CAPESSciEL

Sub-diffractional, volume-confined polaritons in a natural hyperbolic material: hexagonal boron nitride

Strongly anisotropic media where the principal components of the dielectric tensor have opposite signs are called hyperbolic. Such materials length exhibit unique nanophotonic properties enabled by the highly directional propagation of slow-light modes localized at deeply sub-diffractional scales. While artificial hyperbolic metamaterials have been demonstrated, they suffer from high plasmonic losses and require complex nanofabrication, which in turn induces the size-dependent limitations on optical confinement. The low-loss, mid-infrared, natural hyperbolic material, hexagonal boron nitride is an attractive alternative. We observe four series of multiple (up to seven) 'hyperbolic polariton' modes in boron nitride nanocones in two spectral bands. The resonant modes obey the predicted aspect ratio dependence and exhibit record-high quality factors (Q up to 283) in the strong confinement regime (lambda/86 in the smallest structures). These observations assert hexagonal boron nitride as a promising platform for studying novel regimes of light-matter interactions and nanophotonic device engineering

Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

Search for direct stau production in events with two hadronic tau-leptons in root s=13 TeV pp collisions with the ATLAS detector

A search for the direct production of the supersymmetric partners ofτ-leptons (staus) in final stateswith two hadronically decayingτ-leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of139fb−1, recorded with the ATLAS detector at the LargeHadron Collider at a center-of-mass energy of 13 TeV. No significant deviation from the expected StandardModel background is observed. Limits are derived in scenarios of direct production of stau pairs with eachstau decaying into the stable lightest neutralino and oneτ-lepton in simplified models where the two staumass eigenstates are degenerate. Stau masses from 120 GeV to 390 GeV are excluded at 95% confidencelevel for a massless lightest neutralino

Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV

Studies of new Higgs boson interactions through nonresonant HH production in the b¯bγγ fnal state in pp collisions at √s = 13 TeV with the ATLAS detector

A search for nonresonant Higgs boson pair production in the b ¯bγγ fnal state is performed using 140 fb−1 of proton-proton collisions at a centre-of-mass energy of 13 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. This analysis supersedes and expands upon the previous nonresonant ATLAS results in this fnal state based on the same data sample. The analysis strategy is optimised to probe anomalous values not only of the Higgs (H) boson self-coupling modifer κλ but also of the quartic HHV V (V = W, Z) coupling modifer κ2V . No signifcant excess above the expected background from Standard Model processes is observed. An observed upper limit µHH < 4.0 is set at 95% confdence level on the Higgs boson pair production cross-section normalised to its Standard Model prediction. The 95% confdence intervals for the coupling modifers are −1.4 < κλ < 6.9 and −0.5 < κ2V < 2.7, assuming all other Higgs boson couplings except the one under study are fxed to the Standard Model predictions. The results are interpreted in the Standard Model efective feld theory and Higgs efective feld theory frameworks in terms of constraints on the couplings of anomalous Higgs boson (self-)interactions

Model-independent search for the presence of new physics in events including H → γγ with s \sqrt{s} = 13 TeV pp data recorded by the ATLAS detector at the LHC

Abstract A model-independent search for new physics leading to final states containing a Higgs boson, with a mass of 125.09 GeV, decaying to a pair of photons is performed with 139 fb−1 of s $$\sqrt{s}$$ = 13 TeV pp collision data recorded by the ATLAS detector at the Large Hadron Collider at CERN. This search examines 22 final states categorized by the objects that are produced in association with the Higgs boson. These objects include isolated electrons or muons, hadronically decaying τ-leptons, additional photons, missing transverse momentum, and hadronic jets, as well as jets that are tagged as containing a b-hadron. No significant excesses above Standard Model expectations are observed and limits on the production cross section at 95% confidence level are set. Detector efficiencies are reported for all 22 signal regions, which can be used to convert detector-level cross-section limits reported in this paper to particle-level cross-section constraints