1,742 research outputs found

    The double parton distributions in the hard pomeron model

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    We study the double parton interaction process in collisions between highly virtual qqˉq{\bar q} pairs in the BFKL regime. Explicit expressions for the double parton distributions are obtained both in the case of direct coupling of the BFKL pomerons to the qqˉq{\bar q} pair and in the case of triple pomeron interaction.Comment: 29 pages, 6 figure

    The N - Jet Inclusive Cross-Section in the Hard Pomeron Model

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    The inclusive production of several jets is studied in the framework of the hard pomeron model. The average jet momenta are found to be strongly ordered and growing towards the central c.m. rapidity, as expected. Strong positive correlations are found for pairs of jets neighbouring in rapidity, both in the forward-backward and forward-forward directions.Comment: 20 pages, latex, one figure (fig.2), an hard copy of fig.1 can be obtained on reques

    The bootstrap for impact factors and the gluon wave function

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    Using the results recently obtained for the non-forward quark and gluon impact factors, it is shown that their form in the gluon colour channel is consistent with the ``third bootstrap condition'', namely, that they should be proportional to the gluon wave function. The gluon wave function found from this assumption is used to write the full bootstrap condition for the gluonic potential in the next-to-leading order.Comment: Latex, 7 page

    Energy loss as the origin of an universal scaling law of the elliptic flow

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    It is shown that the excellent scaling of the elliptic flow found for all centralities, species and energies from RHIC to the LHC for pTp_{T} less than the saturation momentum is a consequence of the energy lost by a parton interacting with the color field produced in a nucleus-nucleus collision. In particular, the deduced shape of the scaling curve describes correctly all the data. We discuss the possible extensions to higher pTp_{T}, proton-nucleus and proton-proton collisions as well as higher harmonics.Comment: 10 pages, 2 figure

    Evolution of the gluon density in x with a running coupling constant

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    This is a draft describing the calculation of the evolution of the gluon density in xx from an initial value x=x0=0.01x=x_{0}=0.01 to smaller values, up to x=108x=10^{-8} in the hard pomeron formalism with a running coupling introduced on the basis of the bootstrap equation. The obtained gluon density is used to calculate the singlet part of the proton structure function. Comparison with experiment and the results following from the fixed coupling evolution is made.Comment: 10 pages, Latex, 10 postscript figure

    Jet production from the perturbative QCD pomeron with a running coupling constant

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    An analysis of minijet production from the hard pomeron with a running coupling constant is performed. Two supercritical pomerons found in the numerical study are taken into account. The calculated inclusive jet production rate is finite at small kk_{\bot} and behaves like 1/k41/k^{-4}_{\bot} at high kk_{\bot} modulo factors coming from logarithmic terms. The average kk_{\bot} is found to be very large (1013GeV/c\sim 10-13 GeV/c) and practically independent of energy. This is interpreted as an indication that at present energies we are still far from the asymptotics and that, apart from supercritical pomerons, other states contribute significantly

    The Effectiveness of using Total System Power for Fault Detection in Rooftop Units

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    Previous research has been presented that suggests using instantaneous system power measurements can be used to perform fault detection for rooftop units. The methodology generates a normal system power model using measurements of system power and outdoor-air temperature, which can be then used to determine if system performance has deviated due to the presence of faults. This work presents data collected from several rooftop units subjected to different faults and ambient conditions using psychrometric chamber test facilities. The results of the testing show that total system power is not very sensitive to many common faults affecting direct-expansion air-conditioning equipment. In fact, only condenser fouling faults increase instantaneous power at significant levels. Other faults, such as improper refrigerant charge level, liquid-line restriction, or compressor valve leakage, may lead to total power reduction and also, in general, have relatively weak impacts on total system power.  Virtual sensor measurements of total cooling capacity or coefficient of performance (COP) are more sensitive fault detection indicators than system power

    Lab and Field Evaluation of Fault Detection and Diagnostics for Advanced Roof Top Unit

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    In this paper, the results of lab and field evaluation of several RTU FDD technologies will be presented and discussed. The focus the study was on RTUs that provide cooling of small and medium commercial buildings. This work was conducted by UTRC in close collaboration Purdue University within Consortium for Building Energy Innovation (CBEI). The goal of the lab activity was to engineer and assess low-cost, embeddable fault detection and diagnostics (FDD) for a new RTU product that exceeds DOE\u27s High Performance RTU performance specification. Primary focus of evaluation was on overall unit performance degradation (COP and capacity) resulted from single and multiple operational faults. High confidence and low false alarm rate of COP degradation were demonstrated. The cost effectiveness of FDD will be discussed. Due to high interest and close engagement of Original Equipment Manufacturer (OEM) and National Account Customer field evaluation of FDD became possible. Several commercial sited with state-of-the-art RTUs were instrumented for continues monitoring of RTU performance and assessment of frequency of typical operational faults. Also some operational faults are intentionally injected in order evaluate FDD effectiveness. Several levels of FDD applicable in the field will be discussed

    Finite formation time effects in quasi-elastic (e,e)(e,e') scattering on nuclear targets

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    The problem of the final state interaction in quasi-elastic (e,e)(e,e') scattering at large Q2Q^2, is investigated by exploiting the idea that the ejected nucleon needs a finite amount of time to assume its asymptotic form. It is shown that when the dependence of the scattering amplitude of the ejected nucleon on its virtuality is taken into account, the final state interaction is decreased. The developed approach is simpler to implement than the one based on the color transparency description of the damping of the final state interaction, and is essentially equivalent to the latter in the case of the single rescattering term. The (e,e)(e,e') process on the deuteron is numerically investigated and it is shown that, at x=1x=1, appreciable finite formation time effects at Q2Q^2 of the order of 10 (GeV/c)2^2 are expected.Comment: 23 pages, 3 figure
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