603 research outputs found

    Enhancement of prompt photons in ultrarelativistic proton-proton collisions from nonlinear gluon evolution at small-xx

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    In this paper we estimate the influence of nonlinear gluon evolution in the production of prompt photons at the LHC pp collider. We assume the validity of collinear factorization and consider the EHKQS parton distributions, which are solutions of the GLR-MQ evolution equations and describe quite well the DESY epep HERA data, as input in our calculations. We find that both single and double photon production are enhanced for low-pTp_T photons and central rapidities, while this effect is absent for the high-pTp_T photons. The implications of this effect for the Quark-Gluon Plasma searches and for the QCD background to Higgs are also discussed.Comment: 4 pages, 4 figures. Version to be published in Physical Review

    Nuclear Medium Effects in J/ΨJ/\Psi Production at HERA-B

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    In this paper we estimate the influence of the shadowing effect and initial state parton energy loss in the quarkonium production at HERA-B. We analyze the xFx_F behavior of the effective exponent α(xF)\alpha (x_F) and present a comparison with the preliminary HERA-B data for J/ΨJ/\Psi production. Moreover, we estimate the magnitude of these effects in the J/ΨJ/\Psi production at RHIC.Comment: 9 pages, 4 figure

    Prompt J/psi production at the LHC

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    Models with essential non-perturbative QCD dynamics for the production of charmonium are extrapolated to give predictions of prompt J/psi production at the LHC. Differences of up to an order of magnitude occurs, although the different models all describe the Tevatron data on high-pT charmonium. An important point is here the treatment of higher order perturbative QCD effects. We also discuss the large rate of prompt J/psi from these models as a background to CP violation studies.Comment: 8 pages, 8 eps figure

    Diffractive Higgs boson production at the Tevatron and LHC

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    Improved possibilities to find the Higgs boson in diffractive events, having less hadronic activity, depend on whether the cross section is large enough. Based on the soft color interaction models that successfully describe diffractive hard scattering at HERA and the Tevatron, we find that only a few diffractive Higgs events may be produced at the Tevatron, but we predict a substantial rate at the LHC.Comment: 4 pages, 4 figures, uses Revtex

    Viscosity, Boson Peak and Elastic Moduli in the Na2O-SiO2 System

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    The temperature and chemical dependence of the melt viscosity are ubiquitous in the model development of the volcanic dynamics, as well as in the glass production and design. We focussed on the yet-explored relationship between the bulk and shear moduli ratio and boson peak with the melt fragility of their parental glasses. Here, we explored the extension of the observed trend by testing the conventional binary system Na2O-SiO2, thus providing new evidence supporting the link between the flow of melts and supercooled liquids and the vibrational dynamics of their parental glasses. This was accomplished by integrating new low-frequency Raman measurements and integrating data from the literature on Brillouin light scattering and viscometry. This approach allows us to feed the MYEGA equation with reliable input parameters to quantitatively predict the viscosity of the Na2O-SiO2 system from the liquid up to the glass transition

    Controle químico da ferrugem (Hemileia vastatrix Berk & BR.) do cafeeiro (Coffea arabica, L.) e seus efeitos na produção, nas condições do estado de Rondônia.

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    Durante cinco anos consecutivos foi desenvolvido no município de Cacoal, RO, um experimento visando avaliar o comportamento da ferrugem do cafeeiro e determinar um programa adequado de aplicação de produto químico, para o seu controle. A doença desenvolveu-se rapidamente, durante os meses de dezembro e janeiro e se manteve em níveis elevados ate a colheita, depois declinou progressivamente, ate o mês de agosto, permanecendo em baixo índice ate outubro. O retardamento do inicio das aplicações de fungicida permitiu a livre evolução da ferrugem nesse período, o que proporcionou efeito negativo, principalmente no programa de pulverizações janeiro-abril. O mesmo comportamento da ferrugem foi observado, adiantando-se o termino das aplicações, pois a incidência da doença a níveis elevados ocorreu após fevereiro, causando danos a produção do ano seguinte. Os programas de maior eficiência no controle da ferrugem e aumento da produção, foram os que estabeleceram pulverizações nos períodos de outubro a abril e novembro a abril

    Integrating virtual reality and gis tools for geological mapping, data collection and analysis: An example from the metaxa mine, santorini (Greece)

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    In the present work we highlight the effectiveness of integrating different techniques and tools for better surveying, mapping and collecting data in volcanic areas. We use an Immersive Virtual Reality (IVR) approach for data collection, integrated with Geographic Information System (GIS) analysis in a well-known volcanological site in Santorini (Metaxa mine), a site where volcanic processes influenced the island’s industrial development, especially with regard to pumice mining. Specifically, we have focused on: (i) three-dimensional (3D) high-resolution IVR scenario building, based on Structure from Motion photogrammetry (SfM) modeling; (ii) subsequent geological survey, mapping and data collection using IVR; (iii) data analysis, e.g., calculation of extracted volumes, as well as production of new maps in a GIS environment using input data directly from the IVR survey; and finally, (iv) presentation of new outcomes that highlight the importance of the Metaxa Mine as a key geological and volcanological geosite

    Fabrication and Results of the First MgB2 Round Coil Superferric Magnet at LASA

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    The LASA Laboratory (INFN, Milan) is working in the High Luminosity LHC program to develop, in collaboration with CERN, six different types of High Order corrector magnets. In this framework, in parallel with a conventional design of superferric magnets with LTS conductor, the LASA is focusing on the research of new superconducting materials which may have applications in particle accelerator magnets. To this purpose, LASA is developing a new type of superferric magnet suitable to arbitrary multipole order, called Round Coil Superferric Magnets (RCSM). The iron yoke shaped with an arbitrary number of poles is able to create the desired harmonic component using only one single round coil with a large bending radius suitable for very strain-sensitive superconductors. The electromagnetic design of a sextupole configuration of the magnet and the production of the first superconducting MgB2 round coil prototype have been already presented. In this paper, we expose the optimization of the iron yoke and polar expansions assembly of the first magnet semi-module prototype. The results of the whole powering test are described in detail and the analysis of the magnetic performances are compared with those of classical superferric correctors
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