Hard gluon evolution in the last stage of the bottom-up thermalization

The study of how fast thermalization in heavy ion collisions occurs has been one of the central topics in the heavy ion community. In the weak coupling picture this thermalization occurs from 'the bottom up': high energy partons, formed early in the collision, radiate low energy gluons which then proceed to equilibrate among themselves, forming a thermal bath that brings the high energy sector to equilibrium. In this scheme we apply a model on parton energy loss to discuss the effects of medium expansion on the thermalization problem and estimate the average transverse momentum diffusivity for thermalization in a Bjorken expanding medium.Comment: 8 pages, 4 figures. Current version includes updated references and a more detailed discussion on the underlying assumption

On the renormalization group flow of f(R)-gravity

We use the functional renormalization group equation for quantum gravity to construct a non-perturbative flow equation for modified gravity theories of the form $S = \int d^dx \sqrt{g} f(R)$. Based on this equation we show that certain gravitational interactions monomials can be consistently decoupled from the renormalization group (RG) flow and reproduce recent results on the asymptotic safety conjecture. The non-perturbative RG flow of non-local extensions of the Einstein-Hilbert truncation including $\int d^dx \sqrt{g} \ln(R)$ and $\int d^dx \sqrt{g} R^{-n}$ interactions is investigated in detail. The inclusion of such interactions resolves the infrared singularities plaguing the RG trajectories with positive cosmological constant in previous truncations. In particular, in some $R^{-n}$-truncations all physical trajectories emanate from a Non-Gaussian (UV) fixed point and are well-defined on all RG scales. The RG flow of the $\ln(R)$-truncation contains an infrared attractor which drives a positive cosmological constant to zero dynamically.Comment: 55 pages, 7 figures, typos corrected, references added, version to appear in Phys. Rev.

Fractional Hamiltonian analysis of higher order derivatives systems

The fractional Hamiltonian analysis of 1+1 dimensional field theory is investigated and the fractional Ostrogradski's formulation is obtained. The fractional path integral of both simple harmonic oscillator with an acceleration-squares part and a damped oscillator are analyzed. The classical results are obtained when fractional derivatives are replaced with the integer order derivatives.Comment: 13 page

Integração lavoura-pecuária-floresta. 2. Identificação e implantação de forrageiras na integração lavoura-pecuária.

RESUMO: Nos sistemas de integração Lavoura-Pecuária (iLP) existem arranjos e métodos de formação de pastagens que permitem aumentar a produção animal e alterar o ambiente, tornando-o mais favorável à produção de grãos. O cultivo de forrageiras solteiras ou em consórcio com culturas tem crescido, mas este assunto é novo para muitos técnicos e agricultores que têm dificuldade na identificação das espécies e cultivares de forrageiras. Com isso, eles têm dificuldade em implantar as pastagens e estabelecer seu manejo. Existem algumas características morfológicas, relacionadas à folha, à presença de cera e pelos e ao tipo de inflorescência, que permitem a identificação das cultivares de forrageira no campo, com facilidade. Entre as forrageiras disponíveis no mercado existem algumas como milheto, sorgo, Panicum maximum e Brachiaria spp., que apresentam características mais favoráveis ao cultivo em sistemas de iLP. Algumas forrageiras estabelecem com facilidade e são mais produtivas durante a estação seca e, ainda, são controladas com menor dose de herbicida e morrem com maior rapidez. Assim, é necessário menos tempo entre a dessecação e o estabelecimento de uma nova cultura em sucessão. Crop-Livestock-Forest Integration System. 2. Identifying and Establishing Forages in Integrated Crop-Livestock. ABSTRACT: There are arrangements and methods to establishing pasture in croplivestock integration systems (CLI) that may increase animal production and change cropping environment, making it more favorable to grain production. Cultivation of forages, either alone or mixed with other crops, has been improved, but this is a new subject to many farmers and technicians who have difficulty in identifying forage species and cultivars. Therefore, it is hard to assess forage establishment and appropriate management. There are some morphological characteristics related to leaves, to waxy and pubescence and to type of inflorescence which make easy to identify different cultivars in the field. Pearl millet, sorghum, Panicum maximum and Brachiaria spp. are some commercial forages which are suitable to CLI systems. Some forages are easily established and are more productive during dry season; additionally, they are burned down with a lower dose of herbicide and die more quickly. So, the time between the desiccation and the establishment of a new crop in succession is shorter.bitstream/item/60551/1/DOC.111.2011.CPAO.pd

Avaliação da resistência de variedades de mangueira Mangifera indica L., do BAG manga da Embrapa Mandioca e Fruticultura, ao fungo Coletotrichum gloeosporioides, Penz.).

O Brasil está entre os nove principais produtores de manga do mundo, com uma área de 67 mil hectares. Atualmente, a Tommy Atkins é a variedade mais produzida e a que possui a maior participação no volume comercializado no mundo, devido, principalmente, as suas características fenológicas e organolépticas

Nuclear transverse momentum imbalance in the color dipole approach at the LHC regime

Transverse momentum broadening of a parton propagating through a large nucleus is evaluated in the color dipole approach using different models for the dipole cross section or unintegrated gluon distribution, which lead to different values of the coefficient $C_{\mathcal{F}}(0,s)$. Numerical calculations are compared to data extracted from LHCb and ALICE experiments for nuclear broadening of $J/\psi$. We find that different models which describe the small-$x$ data predict values of $\Delta p_T^2$ that agree reasonably well with experiment, specially for forward rapidity. The centrality dependence was also analysed and the models are consistent with the ALICE measurements.Comment: 6 pages, 2 figure, 2 table