2,048 research outputs found

    Microscopic Description of Deeply Virtual Compton Scattering off Spin-0 Nuclei

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    We evaluate within a microscopic calculation the contributions of both coherent and incoherent deeply virtual Compton scattering from a spin-0 nucleus. The coherent contribution is obtained when the target nucleus recoils as a whole, whereas for incoherent scattering break-up configurations for the final nucleus into a an outgoing nucleon and an A−1A-1 system are considered. The two processes encode different characteristics of generalized parton distributions.Comment: 7 pages, 3 figure

    Nuclear Medium Modifications of Hadrons from Generalized Parton Distributions

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    We study the structure of generalized parton distributions in spin 0 nuclei within a microscopic approach for nuclear dynamics. GPDs can be used on one side as tools to unravel the deep inelastic transverse structure of nuclei in terms of both transverse spatial and transverse momentum degrees of freedom. On the other, one can obtain information on GPDs themselves by observing how they become modified in the nuclear environment. We derive the structure of the nuclear deeply virtual Compton scattering tensor and generalized parton distributions at leading order in QQ in a field-theoretical framework. The nuclear generalized parton distributions are calculated using a two step process -- the convolution approach -- where the scattering process happens from a quark inside a nucleon, itself inside a nucleus, disregarding final state interactions with both the nuclear and nucleon debris. We point out that details of the nuclear long range interactions such as two-body currents, can be disregarded compared to the deep inelastic induced modifications of the bound GPDs. We show how the pattern of nuclear modifications predicted, and in particular the deviations of off-shell effects from the longitudinal convolution provide clear signals to be sought in experimental measurements. Finally, we find interesting relationships by studying Mellin moments in nuclei: in particular we predict the AA-dependence for the DD-term of GPDs within a microscopic approach, and the behavior with tt of the total momentum carried by quarks in a nucleus. The latter provides an important element for the evaluation of nuclear hadronization phenomena which are vital for interpreting current and future data at RHIC, HERMES and Jefferson Lab.Comment: 29 pages, 10 figure

    An Evaluation of Multiple Perceptions of Digital Rights Management

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    Digital Rights Management (DRM) solutions have generated much interest because of their influence on the expectations and responsibilities of customers and related organizations. It was created to restrict piracy and enhance digital media sales, however, it is found to be unable to fulfill its objectives. We find the protections by DRM lack an understanding of the end user and the evolving nature of copyright and fair use. The potential motives for pirating appear to increase as DRM becomes more intrusive causing a conflict in the objectives of DRM. Thus, adjustments must be made to the current DRM model in order for it to become beneficial for both the producer and the consumer. Our research identifies the needs, desires, and responsibilities of the various DRM stakeholders so that a successful use of DRM technologies can be modeled: a challenge faced by the media industry

    Generalized Parton Distributions from Hadronic Observables: Zero Skewness

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    We propose a physically motivated parametrization for the unpolarized generalized parton distributions. At zero value of the skewness variable, ζ\zeta, the parametrization is constrained by simultaneously fitting the experimental data on both the nucleon elastic form factors and the deep inelastic structure functions. A rich phenomenology can be addressed based on this parametrization. In particular, we track the behavior of the average: {\it i)} interparton distances as a function of the momentum fraction, XX, {\it ii)} XX as a function of the four-momentum transfer, tt; and {\it iii)} the intrinsic transverse momentum k⊄k_\perp as a function of XX. We discuss the extension of our parametrization to ζ≠0\zeta \neq 0 where additional constraints are provided by higher moments of the generalized parton distributions obtained from {\it ab initio} lattice QCD calculations.Comment: 42 pages, 21 figure

    Mass and Number and Its Chemical Composition Distribution of Particulate Matter in Different Microenvironments

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    Adverse health effects from exposure to air pollution are a global challenge and of widespread concern. Therefore, the present study attempted to pave the way in the study of indoor air pollution by coarse and fine particulate matter and picturesque its relation with the different indoor microenvironment. A campaign study was conducted in the city of Taj “Agra,” India in which different microenvironments were selected (i.e., offices, shops, and commercial centers). For each site, two different locations were chosen to examine the coarse particles (PM10 and PM5.0) and fine particles (PM2.5, PM1.0, PM0.5 and PM0.25) concentrations and metal concentration of Zn, Pb, Ni, Fe, Cr, Cd, Mg and Cu in PM2.5 and for their related health effects. The exposure factor and health risk assessment for carcinogenic effects due to heavy metal contaminants have also been calculated for adults working in different microenvironment by following the methodology prescribed by US EPA
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