4,586 research outputs found

    Scalar and higher even spin glueball masses from an anomalous modified holographic model

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    In this work, within an anomalous modified holographic softwall model, we calculate analytically the masses of the scalar glueball with its radial excitations and higher even glueball spin states, with P=C=+1P=C=+1, from a single mass equation. Using this approach we achieved an unified treatment for both scalar and high even spin glueballs masses. Furthermore, we also obtain the Regge trajectory associated with the pomeron compatible with other approaches.Comment: V4: 14 pages, 3 tables, 1 figure. Text improved. New references included. Typos corrected. Results slightly modified due to the improvement of the statistical analysis. This version matches the published one in EP

    Holographic Description of Chiral Symmetry Breaking in a Magnetic Field in 2+1 Dimensions with an Improved Dilaton

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    We consider a holographic description of the chiral symmetry breaking in an external magnetic field in (2+1) (2+1) -dimensional gauge theories from the softwall model using an improved dilaton field profile given by Φ(z)=kz2+(k+k1)z2tanh(k2z2)\Phi(z) = - kz^2 + (k+k_1)z^2\tanh (k_{2}z^2). We find inverse magnetic catalysis for BBcBB_c, where BcB_c is the pseudocritical magnetic field. The transition between these two regimes is a crossover and occurs at B=BcB=B_c, which depends on the fermion mass and temperature. We also find spontaneous chiral symmetry breaking (the chiral condensate σ0\sigma \not=0) at T=0T=0 in the chiral limit (mq0m_q\to 0) and chiral symmetry restoration for finite temperatures. We observe that changing the kk parameter of the dilaton profile only affects the overall scales of the system such as BcB_c and σ\sigma. For instance, by increasing kk one sees an increase of BcB_c and σ\sigma. This suggests that increasing the parameters k1k_1 and k2k_2 will decrease the values of BcB_c and σ\sigma.Comment: V2: 13 pages, 10 figures. New figure added. Text improved. Typos corrected. New references added. Results unchanged. This version matches the published one in EP

    Reação da cultivar Navelina ISA 315 (Citrus sinensis L. Osb.), à clorose variegada dos citros em condições de campo.

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    A clorose variegada dos citros (CVC), causada pela bactéria Xylella fastidiosa, está presente no Estado de São Paulo desde 1987. Todas as variedades comerciais de laranjas doces são afetadas. Causa redução da produção, principalmente pela acentuada redução no tamanho dos frutos. (LARANJEIRA et al., 2005). A CVC é transmitida por meio de borbulhas contaminadas e por cigarrinhas das famílias Cicadellidae, em citros existem diversas espécies transmissoras de X. fastidiosa, porém a eficiência na transmissão é inferior a 15%, e este índice pode variar entre espécies em função de mecanismos fisiológicos e comportamentais (YAMAMOTO, 2007; LOPES, 1996). Os sintomas característicos da doença são cloroses internervais amareladas na face superior da folha com correspondente necroses de tons de marrom na face inferior, a frutificação tem tendência de ser em pencas onde os frutos tornam-se rígidos, pequenos e com uma concentração de açúcar maior que o normal (LARANJEIRA et al., 2005).pdf 12

    Production, breeding and potential of cowpea crop in Brazil.

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    About 50 years ago cowpea was reported as a relatively minor tropical legume. However, in the last years, it has been emerging as one of the most important food legume of the 21st century (SINGH, 2010). Brazil is not out of this panorama. Brazilian agriculture is undergoing major technological changes and, in addition, globalization in agribusiness has caused impacts on the production chain of several crops, particularly those heavily dependent on the use of a large volume of agricultural inputs, mainly fertilizers and pesticides. Such crops have had a higher production cost each year. On the other hand, this situation has brought new opportunities. Business farmers have sought new alternatives for their production arrangements. In this context cowpea constitutes one of the best options.bitstream/item/85620/1/Doc-216-Production.pd

    THE ADO METHOD FOR SOLVING ONE-DIMENSIONAL DEEP-PENETRATION TRANSPORT PROBLEMS

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    In this work, the Analytical Discrete Ordinate method (ADO method) is used to solve deep-penetration transport problems in one-dimensional Cartesian geometry, subject to isotropic and linear anisotropic scattering effects. The regime is considered permanent, the media are homogeneous, and the fluxes are caused by sources located on the boundaries of the domain. In addition, the energy fluctuations will be considered as not significant, characterizing the phenomena as monoenergetic problems. In order to validate the code, method and provide benchmark results, some test problems will be treated and results will be discussed. In particular, the ADO method generated fairly accurate results when compared to other methods based on SN approaches, at a relatively low computational cost

    Capture of field stars by globular clusters in dense bulge regions

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    The recent detection of a double Red Giant Branch in the optical color-magnitude diagram (CMD) of the bulge globular cluster HP1 (Ortolani et al. 1997), a more populated metal-poor steep one corresponding to the cluster itself, and another metal-rich curved, led us to explore in the present Letter the possibility of capture of field stars by a globular cluster orbiting in dense bulge regions over several gigayears. Analytical arguments, as well as N-body calculations for a cluster model of 10^5 solar masses in a bulge-like environment, suggest that a significant fraction of cluster stars may consist of captures. Metal-poor globular clusters in the inner bulge, like HP1, contrasting at least in Delta [Fe/H] = 1.0 dex with respect to the surrounding metal-rich stars, are ideal probes to further test the capture scenario. In turn, if this scenario is confirmed, the double RGB of HP1 could provide direct estimates of blanketing amounts, which is fundamental for the photometric calibration of metal-rich stellar populations.Comment: 6 pages, 2 included figures, aas2pp4,sty Latex style. To be published in Astrophysical Journal Letter
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