142,360 research outputs found

    Axial Anomaly and the Nucleon Spin

    Get PDF
    In this letter, we have taken a particular Lagrangian, which was introduced to resolve U(1) problem, as an effective QCD Lagrangian, and have derived a formula of the quark content of the nucleon spin. The difference between quark content of the proton (\Delta\Sigma_p) and that of the neutron (\Delta\Sigma_n) is evaluated by this formula. Neglecting the higher-order isospin corrections, this formula can reduce to Efremov's results in the large N_c limit.Comment: (1) A few changes and corrections made following Referee. (2) The difference between quark content of the proton (\Delta\Sigma_p) and that of the neutron (\Delta\Sigma_n) is evaluated. Neglecting the higher-order isospin corrections, this formula can reduce to Efremov's results in the large N_c limi

    Identification of Optimal Locations for Sampling Ground Water for Pesticides in the Mississippi Delta Region of Eastern Arkansas

    Get PDF
    Concerns about the presence of pesticides in the Mississippi River Valley alluvial aquifer in the Arkansas Delta have generated the need to develop a map of ground water vulnerability for this region comprised of approximately 10 million acres. Based on the availability of digital data and the scale of this study. we used a modified Pesticide DRASTIC model in a GRASS GIS environment to identify areas that were physically more sensitive to pesticide contamination than other areas within the Delta. Spatial distribution of pesticide loading was estimated from pesticide application rates in different crops and crop distribution map interpreted from satellite imagery. Relative ground water vulnerability index was expressed as a product of aquifer sensitivity index and pesticide loading index. The resulting map showing the spatial distribution of relative ground water vulnerability index values was intended for use in selecting optimal locations for sampling ground water for pesticides in the Arkansas Delta and for aid in implementing the Arkansas Agricultural Chemical Ground-Water Management Plan. The most sensitive areas in the Delta are distributed mostly along major streams where a combination of shallow depth to ground water, thin confining unit, permeable soils, and high recharge rate usually prevails. It is also in many of these areas where large acres of crops are grown, and pesticides are used. Consequently, many areas along major streams are also most vulnerable. These vulnerable areas may be targeted by planners and governmental agencies for further detailed evaluation. Uncertainties in the methodology and mapped input data, plus the dynamic nature of model factors, require continued and improved efforts in ground water vulnerability assessment for the Arkansas Delta

    Green's function for the Relativistic Coulomb System via Sum Over Perturbation Series

    Full text link
    We evaluate the Green's function of the D-dimensional relativistic Coulomb system via sum over perturbation series which is obtained by expanding the exponential containing the potential term V(x)V({\bf x)} in the path integral into a power series. The energy spectra and wave functions are extracted from the resulting amplitude.Comment: 13 pages, ReVTeX, no figure

    Path integral for a relativistic Aharonov-Bohm-Coulomb system

    Full text link
    The path integral for the relativistic spinless Aharonov-Bohm-Coulomb system is solved, and the energy spectra are extracted from the resulting amplitude.Comment: 6 pages, Revte
    corecore