منابع مشابه
Systematic errors of bound-state parameters obtained with SVZ sum rules
We study systematic errors of the ground-state parameters obtained by Shifman– Vainshtein–Zakharov (SVZ) sum rules, making use of the harmonic-oscillator potential model as an example. In this case, one knows the exact solution for the polarization operator, which allows one to obtain both the OPE to any order and the parameters (masses and decay constants) of the bound states. We determine the...
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This review article discusses the experimental and theoretical status of various Parton Model sum rules. The basis of the sum rules in perturbative QCD is discussed. Their use in extracting the value of the strong coupling constant is evaluated and the failure of the naive version of some of these rules is assessed. This work was supported by the Director, Office of Energy Research, Office of H...
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The chemical potential for a novel intrinsic graph metric, the resistance distance, is briefly recalled, and then a number of »sum rules« for this metric are established. »Global« and »local« types of sum rules are identified. The sums in the »global« sum rules are graph invariants, and the sum rules provide inter-relations amongst different invariants, some involving the resistance distance wh...
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The history and present status of several sum rules for deep-inelastic lepton scattering are reviewed, with particular attention to the discovery of scaling, partons, quarks and QCD. Two outstanding issues are then discussed in more detail: the singlet (Ellis-Jaffe) nucleon spin sum rule and the Drell-Hearn-Gerasimov-Iddings sum rule. 1 Introduction It is a great pleasure to be here today to ho...
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We u s e a q u a n tum loop expansion to derive sum rule constraints on polarized photoabsorption cross sections in the Standard Model, generalizing earlier results obtained by Altarelli, Cabibbo, and Maiani. We s h o w that the logarithmic integral of the spin-dependent photoabsorption cross section R 1 th dd Born () v anishes for any 2 ! 2 process a! bc in the classical, tree-graph approximat...
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ژورنال
عنوان ژورنال: Scholarpedia
سال: 2013
ISSN: 1941-6016
DOI: 10.4249/scholarpedia.8790