134,574 research outputs found

    Large multiplicity fluctuations and saturation effects in onium collisions

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    This paper studies two related questions in high energy onium-onium scattering: the probability of producing an unusually large number of particles in a collision, where it is found that the cross section for producing a central multiplicity proportional to kk should decrease exponentially in k\sqrt{k}. Secondly, the nature of gluon (dipole) evolution when dipole densities become so high that saturation effects due to dipole-dipole interactions become important: measures of saturation are developed to help understand when saturation becomes important, and further information is obtained by exploiting changes of frame, which interchange unitarity and saturation corrections.Comment: 30 pages LaTeX2e, 11 figures included using epsfig. Compressed postscript of whole paper also available at http://www.hep.phy.cam.ac.uk/theory/papers

    High energy scattering in QCD as a statistical process

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    The scattering of two hadronic objects at high energy is similar to a reaction-diffusion process described by the stochastic Fisher-Kolmogorov equation. This basic observation enables us to derive universal properties of the scattering amplitudes in a straightforward way, by borrowing some general results from statistical physics.Comment: 4 pages, 2 figures; talk presented at Baryons 2004, Palaiseau, France, October 200

    From Color Glass to Color Dipoles in high-energy onium--onium scattering

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    Within the Color Glass formalism, we construct the wavefunction of a high energy onium in the BFKL and large-N_c approximations, and demonstrate the equivalence with the corresponding result in the Color Dipole picture. We propose a simple factorization formula for the elastic scattering between two non-saturated ``color glasses'' in the center-of-mass frame. This is valid up to energies which are high enough to allow for a study of the onset of unitarization via multiple pomeron exchanges. When applied to the high energy onium-onium scattering, this formula reduces to the Glauber-like scattering between two systems of dipoles, in complete agreement with the dipole picture.Comment: 35 pages, 2 figure

    The DLLA limit of BFKL in the Dipole Picture

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    In this work we obtain the DLLA limit of BFKL in the dipole picture and compare it with HERA data. We demonstrate that in leading-logarithmic- approximation, where αs\alpha_s is fixed, a transition between the BFKL dynamics and the DLLA limit can be obtained in the region of Q2150GeV2Q^2 \approx 150 GeV^2. We compare this result with the DLLA predictions obtained with αs\alpha_s running. In this case a transition is obtained at low Q2Q^2 (5GeV2)(\le 5 GeV^2). This demonstrates the importance of the next-to-leading order corrections to the BFKL dynamics. Our conclusion is that the F2F_2 structure function is not the best observable for the determination of the dynamics, since there is great freedom in the choice of the parameters used in both BFKL and DLLA predictions.Comment: 14 pages, 2 figures, Accepted for publication in Phys. Lett.

    A Simple Derivation of the JIMWLK Equation

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    A simple derivation of the Jalilian-Marian, Iancu, McLerran, Weigert, Leonidov and Kovner (JIMWLK) equation for the evolution of small-x QCD wavefunctions is given. The derivation makes use of the equivalence between the evolution of a (in general complicated) small-x wavefunction with that of the evolution of the (simple) dipole probing the wavefunction in a high energy scattering.Comment: 11 pages, 3 figures, corrected typo in abstract titl

    Magnetoresistance and localization in bosonic insulators

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    We study the strong localization of hard core bosons. Using a locator expansion we find that in the insulator, unlike for typical fermion problems, nearly all low-energy scattering paths come with positive amplitudes and hence interfere constructively. As a consequence, the localization length of bosonic excitations shrinks when the constructive interference is suppressed by a magnetic field, entailing an exponentially large positive magnetoresistance, opposite to and significantly stronger than the analogous effect in fermions. Within the forward scattering approximation, we find that the lowest energy excitations are the most delocalized. A similar analysis applied to random field Ising models suggests that the ordering transition is due to a delocalization initiated at zero energy rather than due to the closure of a mobility gap in the paramagnet

    Oral Protein Therapy for the Future - Transport of Glycolipid-Modified Proteins: Vision or Fiction?

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    The reliable and early diagnosis of common complex multifactorial diseases depends on the individual determination of all (or as many as possible) polymorphisms of each susceptibility gene together with amount and type of the corresponding gene products and their downstream effects, including the synthesis and flux of metabolites and regulation of signalling processes. In addition, this system's biology-driven personalized diagnosis must be accompanied by options for personalized reliable and early therapy. In the midterm, the direct substitution or inhibition of the proteins encoded by the corresponding defective gene products of the susceptibility genes exerting lower or higher activity by administration of the `normal' proteins or inhibitory antibodies, respectively, seems to be most promising. The critical hurdle of oral bioavailability as well as transport into the cytoplasm of the target cells, if required, could be overcome by therapeutic proteins with carboxy-terminal modification by glycosylphosphatidylinositol (GPI). This may be deduced from recent experiments with rat adipocytes. Here this membrane-anchoring glycolipid structure induces the sequential transport of proteins from special regions of the plasma membrane via the surface of intracellular lipid droplets to special membrane vesicles, which are finally released from the adipocytes together with the associated GPI proteins. It remains to be studied whether similar molecular mechanisms operate in intestinal epithelial cells and may enable the transport of GPI proteins from the intestinal lumen into the blood stream. If so, modification of proteins encoded by (combinations of) susceptibility genes with GPI could significantly facilitate the personalized therapy of common diseases on the basis of `inborn' safety, efficacy, rapid realization and oral application. Copyright (C) 2010 S. Karger AG, Base

    'Daniel Defoe, Master of Genres'

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