828 research outputs found

    The BFKL-Pomeron In Deep Inelastic Diffractive Dissociation near t=0

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    The small-tt behaviour of the deep inelastic diffractive dissociation cross section in the triple Regge region is investigated, using the BFKL approximation in perturbative QCD. We show that the cross section is finite at t=0t=0, but the diffusion in lnkt2\ln{k_t^2} leads to a large contribution of small momenta at the triple Pomeron vertex. We study the dependence upon the total energy and the invariant mass. At t=0t=0, there is a decoupling of the three BFKL singularities which is a consequence of the conservation of the conformal dimension. For large invariant masses, the four gluon state in the upper t-channel plays an important role and cannot be neglected.Comment: 43 pages, LaTex , 11 ps-figures (uuencoded) appende

    Treatment of dogs with compensated myxomatous mitral valve disease with spironolactone-a pilot study

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    Spironolactone improves outcome in dogs with advanced myxomatous mitral valve disease (MMVD). Its efficacy in preclinical MMVD is unknown. The hypothesis was the administration of spironolactone to dogs with compensated MMVD demonstrating risk factors for poorer prognosis will decrease the rate of disease progression. The aim was to provide pilot data to evaluate preliminary effects and sample size calculation for a definitive clinical trial

    The potential hazard of staphylococci and micrococci to human subjects in a life support systems evaluator and on a diet of precooked freeze dehydrated foods

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    Distribution, and hazards of indigenous microbial populations in humans during prolonged space flight simulatio

    The γγ\gamma^*\gamma^* Total Cross Section and the BFKL Pomeron at e+ee^{+}e^{-} Collider

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    We present a numerical estimate of the γγ\gamma^* \gamma^* total cross section at LEP and at the designed e+ee^+e^- Next Linear Collider (NLC), based upon the BFKL Pomeron. We find for the linear collider that the event rate is substantial provided electrons scattered under small angles can be detected, and a measurement of this cross section provides an excellent test of the BFKL Pomeron. For LEP, although the number of events is substantially smaller, an initial study of this process is feasible.Comment: 10 pages, latex, 5 figures included using epsfi

    Relationship of the Membrane ATPase from Halobacterium saccharovorum to Vacuolar ATPases

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    Polyclonal antiserum against subunit A (67 kDa) of the vacuolar ATPase from Neurospora crassa reacted with subunit I (87 kDa) from a membrane ATPase of the extremely halophilic archaebacterium Halobacterium saccharovorum. The halobacterial ATPase was inhibited by nitrate and N-ethylmaleimide; the extent of the latter inhibition was diminished in the presence of adenosine di- or triphosphates. 4-Chloro-7-nitrobenzofurazan in- hibited the hatobacterial ATPase also in a nucleotide- protectable manner; the bulk of inhibitor was associated with subunit II (60 kDa). The data suggested that this halobacterial ATPase may have conserved structural features from both the vacuotar and the F-type ATPases

    Inclusive 1-jet Production Cross Section at Small x in QCD: Multiple Interactions

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    We study corrections due to two Pomeron exchanges to the inclusive 1-jet production cross section in the Regge limit of perturbative QCD for a finite number of colors. By considering deep inelastic scattering on a weakly bound two-nucleon system, we carefully follow the logic of the AGK cutting rules and show, for the single inclusive cross section, that, due to the reggeization of the gluon, modifications of the AGK cutting rules appear. As our main result, we investigate and calculate the jet production vertex in the presence of a two-Pomeron cut correction. Compared to previous studies, we find a novel structure of the jet vertex which has not been considered before. We discuss a few implications of this new piece.Comment: 42 pages, 22 figures, few references and comments added, to appear on JHE

    Azimuthal Distribution of Quark-Antiquark Jets in DIS Diffractive Dissociation

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    We investigate the azimuthal distribution of quark-antiquark jets in DIS diffractive dissociation with large transverse momentum. In this kinematical region the matrix element is expressed in terms of the gluon structure function. For the transverse part of the cross section we find a cos(2ϕ)\cos(2 \phi)-distribution with the maximum at ϕ=±π/2\phi = \pm \pi/2, i.e.\ the jets prefer a direction perpendicular to the electron plane. This is in contrast to boson gluon fusion where the qqˉq\bar{q} jet cross section for transversely polarized bosons peaks at ϕ=0\phi=0 and ϕ=π\phi=\pi. We discuss the origin of this striking difference and present numerical results relevant for the diffractive dissociation at HERA.Comment: 12 pages, latex, 7 figure

    Diffractive Meson Production and the Quark-Pomeron Coupling

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    Diffractive meson production at HERA offers interesting possibilities to investigate diffractive processes and thus to learn something about the properties of the pomeron. The most succesful phenomenological description of the pomeron so far assumes it to couple like a C=+1C = +1 isoscalar photon to single quarks. This coupling leads, however, to problems for exclusive diffractive reactions. We propose a new phenomenological pomeron vertex, which leads to very good fits to the known data, but avoids the problems of the old vertex.Comment: 20 pages, latex with uuencoded postscript, revised versio
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