6,504 research outputs found

    The unpolarized two-loop massive pure singlet Wilson coefficients for deep-inelastic scattering

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    We calculate the massive two--loop pure singlet Wilson coefficients for heavy quark production in the unpolarized case analytically in the whole kinematic region and derive the threshold and asymptotic expansions. We also recalculate the corresponding massless two--loop Wilson coefficients. The complete expressions contain iterated integrals with elliptic letters. The contributing alphabets enlarge the Kummer-Poincar\'e letters by a series of square-root valued letters. A new class of iterated integrals, the Kummer-elliptic integrals, are introduced. For the structure functions F2F_2 and FLF_L we also derive improved asymptotic representations adding power corrections. Numerical results are presented.Comment: 42, pages Latex, 8 Figure

    Are Neutron-Rich Elements Produced in the Collapse of Strange Dwarfs ?

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    The structure of strange dwarfs and that of hybrid stars with same baryonic number is compared. There is a critical mass (M~0.24M_sun) in the strange dwarf branch, below which configurations with the same baryonic number in the hybrid star branch are more stable. If a transition occurs between both branches, the collapse releases an energy of about of 3x10^{50} erg, mostly under the form of neutrinos resulting from the conversion of hadronic matter onto strange quark matter. Only a fraction (~4%) is required to expel the outer neutron-rich layers. These events may contribute significantly to the chemical yield of nuclides with A>80 in the Galaxy, if their frequency is of about one per 1500 years.Comment: Accepted for publication in IJMP

    The O(α2)O(\alpha^2) Initial State QED Corrections to e+e−e^+e^- Annihilation to a Neutral Vector Boson Revisited

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    We calculate the non-singlet, the pure singlet contribution, and their interference term, at O(α2)O(\alpha^2) due to electron-pair initial state radiation to e+e−e^+ e^- annihilation into a neutral vector boson in a direct analytic computation without any approximation. The correction is represented in terms of iterated incomplete elliptic integrals. Performing the limit s≫me2s \gg m_e^2 we find discrepancies with the earlier results of Ref.~\cite{Berends:1987ab} and confirm results obtained in Ref.~\cite{Blumlein:2011mi} where the effective method of massive operator matrix elements has been used, which works for all but the power corrections in m2/sm^2/s. In this way, we also confirm the validity of the factorization of massive partons in the Drell-Yan process. We also add non-logarithmic terms at O(α2)O(\alpha^2) which have not been considered in \cite{Berends:1987ab}. The corrections are of central importance for precision analyzes in e+e−e^+e^- annihilation into γ∗/Z∗\gamma^*/Z^* at high luminosity.Comment: 4 pages Latex, 2 Figures, several style file

    Gravitational Model of High Energy Particles in a Collimated Jet

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    Observations suggest that relativistic particles play a fundamental role in the dynamics of jets emerging from active galactic nuclei as well as in their interaction with the intracluster medium. However, no general consensus exists concerning the acceleration mechanism of those high energy particles. A gravitational acceleration mechanism is here proposed, in which particles leaving precise regions within the ergosphere of a rotating supermassive black hole produce a highly collimated flow. These particles follow unbound geodesics which are asymptotically parallel to the spin axis of the black hole and are characterized by the energy EE, the Carter constant Q{\cal Q} and zero angular momentum of the component LzL_z. If environmental effects are neglected, the present model predicts at distances of about 140 kpc from the ergosphere the presence of electrons with energies around 9.4 GeV. The present mechanism can also accelerate protons up to the highest energies observed in cosmic rays by the present experiments.Comment: 27 pages and 5 figures. Accepted for publication in Astrophysical Journal. arXiv admin note: text overlap with arXiv:1011.654

    The Unborn and A, B, & C v Ireland

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    From text: A, B, and C v Ireland (ABC-case) arose from an application lodged on 15 July 2005 to the European Court of Human Rights, which was directly referred to the Grand Chambers (thus indicating the importance of the case) for a hearing which commenced on 9 December 2009

    Doramectin e levamizole no controle dos helmintos de bovinos no início da estação seca.

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    Sessenta bovinos da raça Canchim, com idade aproximada de 15 meses e mantidos em pastagem de Brachiaria decumbens Slapf, foram distribuídos aleatoriamente em três tratamentos (l) com 20 animais cada, para controle de nematódeos gastrintestinais (TI- controle; Tj; Dorameclin, ml(/50kg/peso vivo, correspondendo a 200,ug/kg; e TJ Levamizole e ml(/40kg/peso vivo, equivalente a 3, 75mg do princípio ativo por quilograma de peso) A aplicação foi feita via parenteral, Subcutânea, sendo as infecções verminóticas obtidas naturalmente a pasto, O experimento foi realizado na fazenda Canchim, base física do Centro de Pesquisa de Pecuária do Sudeste (CPPSE), em São Carlos, SP, de abril a ,junho de 1995. Foram avaliados o peso corporal (PC), número de ovos por grama de fezes (OPG) e volume corpuscular médio (VCM), por seis períodos (P): 0, 14, 28, 42, 56 e 70 dias pós-dosificação. O modelo de análise incluiu, além da média, os efeitos de T: de P e da interação T x P. A partir dos 14 dias de avaliação, 0 Doraqmectin foi o que apresentou o menor OPG (P0,05) entre esses dois grupos a partir dos 42 dias. Os animais tratados apresentaram ganho de peso semelhantes (P>0,05) até o 42. dia Quanto ao controle, observou-se redução no ganho de peso (P0,05) entre si em toda a fase experimental, observando-se no entanto, valores inferiores (P,0,05) desta variável a partir dos 28 dias no grupo controle

    Prevention of advancing degradation and recovery of degraded lands.

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    This chapter presents an overview on the main technological contributions of Embrapa and partners to halt land degradation, accelerated erosive processes, desertification, sanding, salinization, and to restore degraded lands, as established in target 15.3 (United Nations, 2018): By 2030, combat desertification, restore degraded land and soil, including land affected by desertification, drought and floods, and strive to achieve a land degradation-neutral world.bitstream/item/204882/1/Prevention-of-advancing-degradation-and-recovery-of-degraded-lands-2019.pd
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