The motive of the Fano surface of lines

The purpose of this note is to prove that the Chow motive of the Fano surface of lines on the smooth cubic threefold is finite-dimensional in the sense of Kimura. This gives an example of a smooth projective variety that is not dominated by a product of curves but whose Chow motive is of Abelian type

Scattering Equations and a new Factorization for Amplitudes I: Gauge Theories

In this work we show how a double-cover (DC) extension of the Cachazo, He and Yuan formalism (CHY) can be used to provide a new realization for the factorization of the amplitudes involving gluons and scalar fields. First, we propose a graphic representation for a color-ordered Yang-Mills (YM) and special Yang-Mills-Scalar (YMS) amplitudes within the scattering equation formalism. Using the DC prescription, we are able to obtain an algorithm (integration-rules) which decomposes amplitudes in terms of three-point building-blocks. It is important to remark that the pole structure of this method is totally different to ordinary factorization (which is a consequence of the scattering equations). Finally, as a byproduct, we show that the soft limit in the CHY approach, at leading order, becomes trivial by using the technology described in this paper.Comment: 50+7 pages and typos fixed. Some modifications were made to improve the tex

Una nueva especie de Bryophaenocladius (Diptera: Chironomidae) de Argentina

Se describe y se dibuja el macho de Bryophaenocladius carolinae sp. nov. La especie puede separarse del resto de las especies Neotropicales porque posee una punta anal hialina y triangular, con su punta redondeada; la volsella inferior sub-rectangular y comparativamente más pequeña; gonostilo ensanchado en su parte media y con una quilla externa; R4+5 finalizando opuesta a la terminación de M3+4; escama setosa, pseudospinas y peine en la tibia de la pata dos, ausentes. Se brinda una clave de identificación de adultos machos neotropicales del género Bryophaenocladius Thienemann.The male of Bryophaenocladius carolinae sp. nov. is described and figured. The species can be separated from all other Neotropical species by having a hyaline, blunt triangular anal point, a comparatively small, sub-rectangular inferior volsella, gonostylus widened medially with an outer heel, R4+5 ending opposite to end of M3+4, setose squama and absence of comb on middle tibia and pseudospurs. A key to the adult males of the Neotropical Bryophaenocladius Thienemann is provided.Fil: Donato, Mariano Humberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Laboratorio de Sistemática y Biología Evolutiva; Argentin