1,333 research outputs found

    Geometric scaling in diffractive deep inelastic scattering

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    The geometric scaling property observed in the HERA data at small x, that the deep inelastic scattering (DIS) total cross-section is a function of only the variable Q^2*x^\lambda, has been argued to be a manifestation of the saturation regime of QCD and of the saturation scale Q^2_s(x) x^{-\lambda}. We show that this implies a similar scaling in the context of diffractive DIS and we observe, for several diffractive observables, that the experimental data from HERA confirm the expectations of this scaling.Comment: 9 pages, 3 figures, references added, version to appear in PL

    Gluon production and diffraction in the dipole picture

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    Using the eikonal approximation, we show that inclusive gluon production is related to the scattering of a gluon-gluon dipole while diffractive gluon production in DIS is related to a two-qqˉq\bar q dipole scattering amplitude. Hence diffractive photon dissociation cross-sections are observables that provide potential information on dipole correlations, which represent an open issue in high-energy QCD.Comment: 4 pages, 2 figures, Proceedings of the 10th International Baryons Conference (Baryons04), Ecole Polytechnique, Palaiseau, France, October 25-29 200

    Gaps between jets in double-Pomeron-exchange processes at the LHC

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    The possibility to measure jet-gap-jet final states in double-Pomeron-exchange events at the LHC is presented. In the context of the ATLAS experiment with additional forward physics detectors, cross sections for different experimental settings and gap definitions are estimated. This is done in the framework of the Forward Physics Monte Carlo interfaced with a perturbative QCD model that successfully reproduces standard jet-gap-jet cross sections at the Tevatron. The extrapolation to LHC energies follows from the Balitsky-Fadin-Kuraev-Lipatov dynamics, implemented in the model at next-to-leading logarithmic accuracy.Comment: 8 pages, 5 figures, version to appear in PR

    Energy loss and thermalization of heavy quarks in a strongly-coupled plasma

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    Using the AdS/CFT correspondence, we compute the medium-induced energy loss of a decelerating heavy quark moving through a strongly-coupled supersymmetric Yang Mills plasma. In the regime where the deceleration is small, a perturbative calculation is possible and we obtain the first two corrections to the energy-loss rate of a heavy quark with constant velocity. The thermalization of the heavy quark is also discussed.Comment: 4 pages, no figures, Proceedings of the 21st International Conference on Ultra-Relativistic Nucleus Nucleus Collisions (QM09), Knoxville, USA, March 30-April 4 200

    Next-leading BFKL effects in forward-jet production at HERA

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    We show that next-leading logarithmic (NLL) Balitsky-Fadin-Kuraev-Lipatov (BFKL) effects can be tested by the forward-jet cross sections recently measured at HERA. For d\sigma/dx, the NLL corrections are small which confirms the stability of the BFKL description. The triple differential cross section d\sigma/dxdk_T^2dQ^2 is sensitive to NLL effects and opens the way for an experimental test of the full BFKL theoretical framework at NLL accuracy.Comment: 5 pages, 4 figures, NLL-BFKL saddle-point approximation now compared with exact integration, version to appear in PL

    Dihadron momentum imbalance and correlations in d+Au collisions

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    We calculate in perturbative QCD the transverse momentum imbalance of dijet and dihadron production in high energy p+A (d+A) collisions. We evaluate the effect of both initial- and final-state multiple scattering, which determines the strength of this transverse momentum imbalance. Combining this new result with the suppression of the cross section in d+Au collisions, which arises from cold nuclear matter energy loss and coherent power corrections, we are able to describe the dihadron correlations measured by both PHENIX and STAR collaborations at RHIC, including mid-mid, mid-forward, and forward-forward rapidity hadron pairs.Comment: 12 pages, 6 figure
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