527 research outputs found

    Evidence for breakdown of the DGLAP description in diffractive DIS at HERA

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    HERA data on diffractive DIS show deviations from twist 2 DGLAP predictions below Q25Q^2\sim 5 GeV2^2 at low pomeron ξ\xi, which may reach up to 100%. These deviations are consistent with higher twists effects extracted from the saturation model. It is a first direct evidence for the higher twists in DIS. This finding affects determination of the diffractive parton densities that are used for the predictions at the LHC.Comment: 5 pages, 2 figures, Based on the talk presented at the conference Deep-Inelastic Scattering and Related Subjects (DIS2012), Bonn, 201

    Evidence of strong higher twist effects in diffractive DIS at HERA at moderate Q2

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    We study a twist decomposition of diffractive structure functions in the diffractive deep inelastic scattering (DDIS) at HERA. At low Q2 and at large energy the data exhibit a strong excess, up to about 100%, above the twist 2 NLO DGLAP description. The excess in consistent with higher twist effects. It is found, that complementing the DGLAP fit by twist 4 and 6 components of the GBW saturation model leads to a good description of data at low Q2. We conclude that the DDIS at HERA provides the first, strong evidence of higher twist effects in DIS.Comment: 4 pages, 2 PDF figure

    Failure detection and isolation analysis of a redundant strapdown inertial measurement unit

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    The objective of this study was to define and develop techniques for failure detection and isolation (FDI) algorithms for a dual fail/operational redundant strapdown inertial navigation system are defined and developed. The FDI techniques chosen include provisions for hard and soft failure detection in the context of flight control and navigation. Analyses were done to determine error detection and switching levels for the inertial navigation system, which is intended for a conventional takeoff or landing (CTOL) operating environment. In addition, investigations of false alarms and missed alarms were included for the FDI techniques developed, along with the analyses of filters to be used in conjunction with FDI processing. Two specific FDI algorithms were compared: the generalized likelihood test and the edge vector test. A deterministic digital computer simulation was used to compare and evaluate the algorithms and FDI systems

    Exclusive ηc\eta_c photo- and electroproduction at HERA as a possible probe of the odderon singularity in QCD

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    Theory and phenomenology of the eta_c photo- and electroproduction is developed from the point of view of probing the odderon singularity in QCD which corresponds to the three gluon exchange mechanism. This mechanism leads to the cross-sections which are independent of W^2 for the exchange of three non-interacting gluons or exhibit increase with increasing W^2 (or 1/x) for the odderon intercept above unity. The \eta_c electroproduction in the three gluon exchange mechanism is shown to be entirely controlled by the transversely polarised virtual photons. The magnitude of the eta_c photoproduction cross-section is estimated to be around 11-45pb. The t-dependence of the differential cross-section is also discussed.Comment: 9 pages, LaTeX, uses epsfig.sty; Numerical error corrected. A factor of 1/3 missing in amplitude in Eq.(8) added. Obtained gamma p -> eta_c p cross-section smaller by a factor of 9 than in the original version of the paper. Figures 4 and 5 changed accordingl

    BFKL Pomeron loop contribution in diffractive photoproduction and inclusive hadroproduction of J/ψJ/\psi and Υ\Upsilon

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    We analyze contributions to the heavy vector meson production with large transverse momentum in proton--proton and diffractive photon--proton scattering driven by an exchange of two Balitsky--Fadin--Kuraev--Lipatov Pomerons in the squared amplitudes. The Pomerons couple to a single parton and form a Pomeron loop closed by the vector meson impact factors. For the photon--proton case the diffractive cut of the Pomeron loop contributes, and for the inclusive hadroproduction one finds the loop with two cut Pomerons. We compute both of these Pomeron loop contributions and study in detail their properties. The results are then used to calculate the cross sections for diffractive J/ψJ/\psi photoproduction with large transverse momentum at HERA and the correlated two Pomeron contribution for inclusive J/ψJ/\psi and Υ\Upsilon production cross sections at the LHC. Within a unified approach a good description of the photoproduction data is found, but correlated two Pomeron mechanism gives only a small contribution to hadroproduction of the vector mesons at the LHC.Comment: 34 pages, 16 figure

    I\u27m Never Going to be Arnold Schwarzenegger : A Study on Fitness Culture in Relation to Young Men\u27s Self-Perceptions

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    Senior Project submitted to The Division of Social Studies of Bard College

    Confining interquark potentials from nonabelian gauge theories coupled to dilaton

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    Following a recently proposed confinement generating mechanism, we provide a new string inspired model with a massive dilaton and a new dilaton coupling function [5]. By solving analytically the equations of motion, a new class of confining interquark potentials is derived which includes several popular potential forms given in the literature.Comment: 7 pages, based on hep-th/0311096. Presented at 10th International Symposium on Meson-Nucleon Physics and the Structure of the Nucleon (MENU 2004), Beijing, China, 29 Aug - 4 Sep 200

    Interactions between cardiac activity and conscious somatosensory perception

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    Fluctuations in the heart's activity can modulate the access of external stimuli to consciousness. The link between perceptual awareness and cardiac signals has been investigated mainly in the visual and auditory domain. Here, we investigated whether the phase of the cardiac cycle and the prestimulus heart rate influence conscious somatosensory perception. We also tested how conscious detection of somatosensory stimuli affects the heart rate. Electrocardiograms (ECG) of 33 healthy volunteers were recorded while applying near‐threshold electrical pulses at a fixed intensity to the left index finger. Conscious detection was not uniformly distributed across the cardiac cycle but significantly higher in diastole than in systole. We found no evidence that the heart rate before a stimulus influenced its detection, but hits (correctly detected somatosensory stimuli) led to a more pronounced cardiac deceleration than misses. Our findings demonstrate interactions between cardiac activity and conscious somatosensory perception, which highlights the importance of internal bodily states for sensory processing beyond the auditory and visual domain

    The Interaction of Food-Quantity Differences and Temporal Presentation on the Amount of Food People Consume

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    Previous research suggests that judgments of food quantity affect the amounts of food people eat. In two experiments, we investigated the interaction of food-quantity differences and temporal presentation on participants ’ judgments of food quantity and the amounts they ate. In Experiment 1, participants viewed drawings of two portions of mashed potatoes presented either simultaneously or sequentially and later recalled sizes from memory. In Experiment 2, participants viewed two serving bowls of pasta salad presented either simultaneously or sequentially and ate as much or as little as they wished from the smaller bowl. The amounts they ate were inversely related to biases in judgments of food quantity
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