Five-leg photon-neutrino interactions

In a first part, we justify the feasibility of substituting a photon leg by a neutrino current in the Euler-Heisenberg Lagrangian to obtain an effective Lagrangian for the process $\gamma\nu\to\gamma\gamma \nu$ and its crossed reactions. We establish the link between these processes and the four-photon scattering in both the Standard Model and the effective theory. As an application, we compute in this effective theory the processes $\gamma\nu\to\gamma\gamma\nu$ and $\gamma\gamma\to\gamma{\nu}\bar\nu$ and show how to use the $\gamma\gamma\to\gamma\gamma$ results as a check. We settle the question of the disagreement between two computations in the literature concerning the reaction $\gamma\gamma\to \gamma \nu\bar\nu$. In the second part, we present results of the direct computation of the photon-neutrino five-leg processes in the Standard Model, discuss possible astrophysical implications of our results, and provide simple fits to the exact expressions.Comment: 6 pages, axodraw, ltwol2e, 5 figures, contributed paper to the 29th International Conference on High Energy Physics (Vancouver

Inelastic photon-neutrino interactions using an effective Lagrangian

We justify the feasibility of substituting a photon leg by a neutrino current in the Euler-Heisenberg Lagrangian to obtain an effective Lagrangian for the process $\gamma\nu\to\gamma\gamma \nu$ and its crossed reactions. We establish the link between these processes and the four-photon scattering in both the Standard Model and the effective theory. As an application, we compute the processes $\gamma\nu\to\gamma\gamma\nu$ and $\gamma\gamma\to\gamma{\nu}\bar\nu$, give their polarized cross sections, and show how to use the $\gamma\gamma\to\gamma\gamma$ results as a check. We settle the question about the disagreement between two computations in the literature concerning the reaction $\gamma\gamma\to \gamma \nu\bar\nu$.Comment: 14 pages, RevTeX, axodraw, 3 figures, comment adde

Omniscopes: Large Area Telescope Arrays with only N log N Computational Cost

We show that the class of antenna layouts for telescope arrays allowing cheap analysis hardware (with correlator cost scaling as N log N rather than N^2 with the number of antennas N) is encouragingly large, including not only previously discussed rectangular grids but also arbitrary hierarchies of such grids, with arbitrary rotations and shears at each level. We show that all correlations for such a 2D array with an n-level hierarchy can be efficiently computed via a Fast Fourier Transform in not 2 but 2n dimensions. This can allow major correlator cost reductions for science applications requiring exquisite sensitivity at widely separated angular scales, for example 21cm tomography (where short baselines are needed to probe the cosmological signal and long baselines are needed for point source removal), helping enable future 21cm experiments with thousands or millions of cheap dipole-like antennas. Such hierarchical grids combine the angular resolution advantage of traditional array layouts with the cost advantage of a rectangular Fast Fourier Transform Telescope. We also describe an algorithm for how a subclass of hierarchical arrays can efficiently use rotation synthesis to produce global sky maps with minimal noise and a well-characterized synthesized beam.Comment: Replaced to match accepted PRD version. 10 pages, 9 fig

CMB Polarization Experiments

We discuss the analysis of polarization experiments with particular emphasis on those that measure the Stokes parameters on a ring on the sky. We discuss the ability of these experiments to separate the $E$ and $B$ contributions to the polarization signal. The experiment being developed at Wisconsin university is studied in detail, it will be sensitive to both Stokes parameters and will concentrate on large scale polarization, scanning a $47^o$ degree ring. We will also consider another example, an experiment that measures one of the Stokes parameters in a $1^o$ ring. We find that the small ring experiment will be able to detect cosmological polarization for some models consistent with the current temperature anisotropy data, for reasonable integration times. In most cosmological models large scale polarization is too small to be detected by the Wisconsin experiment, but because both $Q$ and $U$ are measured, separate constraints can be set on $E$ and $B$ polarization.Comment: 27 pages with 12 included figure

Structured Deformations of Continua: Theory and Applications

The scope of this contribution is to present an overview of the theory of structured deformations of continua, together with some applications. Structured deformations aim at being a unified theory in which elastic and plastic behaviours, as well as fractures and defects can be described in a single setting. Since its introduction in the scientific community of rational mechanicists (Del Piero-Owen, ARMA 1993), the theory has been put in the framework of variational calculus (Choksi-Fonseca, ARMA 1997), thus allowing for solution of problems via energy minimization. Some background, three problems and a discussion on future directions are presented.Comment: 11 pages, 1 figure, 1 diagram. Submitted to the Proceedings volume of the conference CoMFoS1

Tagetes minuta - uma nova alternativa no controle fitoterápico de carrapatos.

Obrigatoriamente os carrapatos são parasitas hematófagos (FREIRE, 1972) da maioria dos animais vertebrados, podendo transmitir uma variedade de agentes patogênicos (ESTRADA-PENA; JONGEJAN, 1999). Depois dos mosquitos os carrapatos são considerados o primeiro grupo de artrópodes ectoparasitos a transmitirem agentes patogênicos aos seres humanos, e ocupam o primeiro lugar na transmissão de agentes causadores de doenças aos animais (JONGEJAN; UILENBERG, 2004; OGRZEWALSKA, 2009). Pertencem ao filo Arthropoda, classe Arachnida, ordem Acari e subordem Ixodida e apresentam uma ampla distribuição geográfica.bitstream/item/109847/1/DOC207.pd

As sementes da Caatinga são...: um levantamento das características das sementes da Caatinga.

O presente trabalho teve por objetivo realizar uma busca ampla sobre a expressão ?As sementes da caatinga são? e encontrar padrões característicos em estudos já realizados. A partir dos resultados da busca pode-se concluir que as sementes da Caatinga são produzidas durante todo o ano, mas a maioria é dispersada no final da estação seca. As sementes da Caatinga apresentam características morfofisiológicas de acordo com os locais onde são produzidas. Algumas sementes da Caatinga apresentam dormência tegumentar, no entanto, é raro encontrar dormência fisiológica. A maioria das sementes da Caatinga são apresentam tolerância a estresses abióticos, embora algumas espécies características deste ecossistema são sensíveis a algumas condições ambientais extremas. A comercialização das sementes da Caatinga ainda é incipiente. As sementes da Caatinga felizmente estão sendo estudadas em várias instituições do Nordeste, do Brasil e do mundo.Edição das Palestras do V Workshop de Tecnologia e Fisiologia de Sementes e Mudas, Petrolina, dez. 2014

Temperature independent band structure of WTe2 as observed from ARPES

Extremely large magnetoresistance (XMR), observed in transition metal dichalcogendies, WTe$_2$, has attracted recently a great deal of research interests as it shows no sign of saturation up to the magnetic field as high as 60 T, in addition to the presence of type-II Weyl fermions. Currently, there has been a lot of discussion on the role of band structure changes on the temperature dependent XMR in this compound. In this contribution, we study the band structure of WTe$_2$ using angle-resolved photoemission spectroscopy (ARPES) and first-principle calculations to demonstrate that the temperature dependent band structure has no substantial effect on the temperature dependent XMR as our measurements do not show band structure changes on increasing the sample temperature between 20 and 130 K. We further observe an electronlike surface state, dispersing in such a way that it connects the top of bulk holelike band to the bottom of bulk electronlike band. Interestingly, similar to bulk states, the surface state is also mostly intact with the sample temperature. Our results provide invaluable information in shaping the mechanism of temperature dependent XMR in WTe$_2$.Comment: 7 pages, 3 figures. arXiv admin note: text overlap with arXiv:1705.0721

The Far-Infrared Background Correlation with CMB Lensing

The intervening large--scale structure distorts cosmic microwave background (CMB) anisotropies via gravitational lensing. The same large--scale structure, traced by dusty star--forming galaxies, also induces anisotropies in the far--infrared background (FIRB). We investigate the resulting inter--dependence of the FIRB and CMB with a halo model for the FIRB. In particular, we calculate the cross--correlation between the lensing potential and the FIRB. The lensing potential can be quadratically estimated from CMB temperature and/or polarization maps. We show that the cross--correlation can be measured with high signal--to--noise with data from the Planck Surveyor. We discuss how such a measurement can be used to understand the nature of FIRB sources and their relation to the distribution of dark matter.Comment: 9 pages, 5 figures, submitted to Ap

Current cosmological constraints from a 10 parameter CMB analysis

We compute the constraints on a ``standard'' 10 parameter cold dark matter (CDM) model from the most recent CMB and data and other observations, exploring 30 million discrete models and two continuous parameters. Our parameters are the densities of CDM, baryons, neutrinos, vacuum energy and curvature, the reionization optical depth, and the normalization and tilt for both scalar and tensor fluctuations. Our strongest constraints are on spatial curvature, -0.24 < Omega_k < 0.38, and CDM density, h^2 Omega_cdm <0.3, both at 95%. Including SN 1a constraints gives a positive cosmological constant at high significance. We explore the robustness of our results to various assumptions. We find that three different data subsets give qualitatively consistent constraints. Some of the technical issues that have the largest impact are the inclusion of calibration errors, closed models, gravity waves, reionization, nucleosynthesis constraints and 10-dimensional likelihood interpolation.Comment: Replaced to match published ApJ version. More details added. 13 ApJ pages. CMB movies and color figs at http://www.hep.upenn.edu/~max/10par_frames.html or from [email protected]