An alternative view on the electroweak interactions

We discuss an alternative to the Higgs mechanism which leads to gauge invariant masses for the electroweak bosons. The key idea is to reformulate the gauge invariance principle which, instead of being applied as usual at the level of the action, is applied at the level of the quantum fields. In other words, we define gauge invariant quantum fields which are used to build the action. In that framework, the Higgs field is not necessarily a physical degree of freedom but can merely be a dressing field that does not propagate. If the Higgs boson is not propagating, the weak interactions must become strongly coupled below 1 TeV and have a non-trivial fixed point and would thus be renormalizable at the non-perturbative level. On the other hand, if a gauge invariant Higgs boson is introduced in the model, its couplings to the fermions and the electroweak bosons can be quite different from those expected in the standard model.Comment: 10 page

Tunable entanglement distillation of spatially correlated down-converted photons

We report on a new technique for entanglement distillation of the bipartite continuous variable state of spatially correlated photons generated in the spontaneous parametric down-conversion process (SPDC), where tunable non-Gaussian operations are implemented and the post-processed entanglement is certified in real-time using a single-photon sensitive electron multiplying CCD (EMCCD) camera. The local operations are performed using non-Gaussian filters modulated into a programmable spatial light modulator and, by using the EMCCD camera for actively recording the probability distributions of the twin-photons, one has fine control of the Schmidt number of the distilled state. We show that even simple non-Gaussian filters can be finely tuned to a ~67% net gain of the initial entanglement generated in the SPDC process.Comment: 12 pages, 6 figure

Coexistence of Pairing Tendencies and Ferromagnetism in a Doped Two-Orbital Hubbard Model on Two-Leg Ladders

Using the Density Matrix Renormalization Group and two-leg ladders, we investigate an electronic two-orbital Hubbard model including plaquette diagonal hopping amplitudes. Our goal is to search for regimes where charges added to the undoped state form pairs, presumably a precursor of a superconducting state.For the electronic density $\rho=2$, i.e. the undoped limit, our investigations show a robust $(\pi,0)$ antiferromagnetic ground state, as in previous investigations. Doping away from $\rho=2$ and for large values of the Hund coupling $J$, a ferromagnetic region is found to be stable. Moreover, when the interorbital on-site Hubbard repulsion is smaller than the Hund coupling, i.e. for $U'<J$ in the standard notation of multiorbital Hubbard models, our results indicate the coexistence of pairing tendencies and ferromagnetism close to $\rho=2$. These results are compatible with previous investigations using one dimensional systems. Although further research is needed to clarify if the range of couplings used here is of relevance for real materials, such as superconducting heavy fermions or pnictides, our theoretical results address a possible mechanism for pairing that may be active in the presence of short-range ferromagnetic fluctuations.Comment: 8 pages, 4 Fig

Quantum key distribution session with 16-dimensional photonic states

The secure transfer of information is an important problem in modern telecommunications. Quantum key distribution (QKD) provides a solution to this problem by using individual quantum systems to generate correlated bits between remote parties, that can be used to extract a secret key. QKD with D-dimensional quantum channels provides security advantages that grow with increasing D. However, the vast majority of QKD implementations has been restricted to two dimensions. Here we demonstrate the feasibility of using higher dimensions for real-world quantum cryptography by performing, for the first time, a fully automated QKD session based on the BB84 protocol with 16-dimensional quantum states. Information is encoded in the single-photon transverse momentum and the required states are dynamically generated with programmable spatial light modulators. Our setup paves the way for future developments in the field of experimental high-dimensional QKD.Comment: 8 pages, 3 figure

Perturbed nuclear matter studied within density functional theory with a finite number of particles

Nuclear matter is studied within the density functional theory framework. Our method employs a finite number of nucleons in a box subject to periodic boundary conditions, in order to simulate infinite matter and study its response to an external static potential. We detail both the theoretical formalism and its computational implementation for pure neutron matter and symmetric nuclear matter with Skyrme-like energy density functionals (EDFs). The implementation of spin-orbit, in particular, is carefully discussed. Our method is applied to the problem of the static response of nuclear matter and the impact of the perturbation on the energies, densities, and level structure of the system is investigated. Our work is a crucial step in our program of ab initio based nuclear EDFs [Phys. Rev. C 104, 024315 (2021)] as it paves the way towards the goal of constraining the EDF surface terms on ab initio calculations

High-dimensional decoy-state quantum key distribution over 0.3 km of multicore telecommunication optical fibers

Multiplexing is a strategy to augment the transmission capacity of a communication system. It consists of combining multiple signals over the same data channel and it has been very successful in classical communications. However, the use of enhanced channels has only reached limited practicality in quantum communications (QC) as it requires the complex manipulation of quantum systems of higher dimensions. Considerable effort is being made towards QC using high-dimensional quantum systems encoded into the transverse momentum of single photons but, so far, no approach has been proven to be fully compatible with the existing telecommunication infrastructure. Here, we overcome such a technological challenge and demonstrate a stable and secure high-dimensional decoy-state quantum key distribution session over a 0.3 km long multicore optical fiber. The high-dimensional quantum states are defined in terms of the multiple core modes available for the photon transmission over the fiber, and the decoy-state analysis demonstrates that our technique enables a positive secret key generation rate up to 25 km of fiber propagation. Finally, we show how our results build up towards a high-dimensional quantum network composed of free-space and fiber based linksComment: Please see the complementary work arXiv:1610.01812 (2016

Nodulação e fixação biológica de nitrogênio de acessos de amendoim com estirpes nativas de rizóbios.

A maximização da fixação biológica de nitrogênio (FBN) em espécies tropicais, costuma ser pouco eficiente uma vez que essas espécies nodulam facilmente com rizóbios nativos. 0 sucesso da seleção de uma simbiose eficiente é dependente do conhecimento da variabilidade genética do macro e do microssimbionte. Objetivou-se, neste estudo, avaliar parâmetros relacionados à capacidade de nodu-lação e fixação biológica de nitrogênio entre acessos de amendoim. Nove acessos de amendoim, cultivados em Aargissolo e Planossolo, foram utilizados, sendo avaliado o número e a massa de nó-dulos, a massa da parte aérea e da raiz, o nitrogênio (N) acumulado, e a redução de acetileno, sob o efeito da população nativa de rizóbios. Os acessos lAC Tatu-ST, lAC 886 Runner, Sapucaia Verme-Iha, Sapucaia Bege e CV Tatuí, mostraram desempenho superior sugerindo que existem variações entre os acessos de amendoim as quais podem ser úteis na seleção de associações eficientes. The maximization of biological nitrogen fixation (BNF) in tropical legume species is generally not efficient because these species can nodulate easily with indigenous rhizobial strains. The selection success of an efficient association depends on the genetic variability of the macro and microsymbi-onto This study aimed to compare nodulation and biological nitrogen fixation parameters among different peanut genotypes. Nine genotypes were cultivated in Argisol and Planosol and shoot, root and nodule dry weight, nodule number, shoot total N content and acetylene reduction activity were evaluated. Under espontaneous nodulation, genotypes lAC Tatu-ST, lAC 886 Runner, Sapucaia Ver-melha, Sapucaia Bege and CV Tatuf showed a better development suggesting that there are differen-ces in the biological nitrogen fixation characteristics among the genotypes studied which may be useful for selecting efficient associations.Parceria: UFRP

Qualidade externa de ovos de codornas de postura alimentadas com farelo de arroz integral em diferentes.

A alimentação representa 70% dos custos de uma produção animal, independente do tamanho e da destinação da mesma. Como principais alimentos fornecidos as aves tem-se o milho, farelo de soja e para redução destes custos torna-se interessante o uso de alimentos alternativos. O arroz é um dos grãos mais produzidos em todo o mundo, sendo o Brasil o décimo maior produtor mundial. Santos et al. (2004) afirmam que o FAI é uma matéria-prima disponível no mercado brasileiro, e pode ser utilizado nas dietas, para diminuir os custos de produção, substituindo o milho, que é a matéria-prima que mais dispende custos às rações avícolas. O farelo de arroz integral (FAI), resultante do polimento dos grãos de arroz, é o mais usado na criação de suínos e aves, considerando os farelos de arroz integral e desengordurado como os subprodutos da indústria do arroz que têm sido incluídos nas dietas de aves (Filardi et al, 2007). A presença de elevada quantidade de gordura, constituída principalmente de ácidos graxos insaturados, predispõe à peroxidação, favorecendo a multiplicação de fungos produtores de aflatoxinas e a rancificação oxidativa, que compromete a qualidade do FAI e dificulta o armazenamento de grandes quantidades. Como forma de prevenir a perda do produto, existem no mercado aditivos químicos e orgânicos. Com isso o objetivo do trabalho foi avaliar a qualidade externa dos ovos de codornas alimentadas com farelo de arroz integral armazenado em diferentes tempos