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Details: frequently used expressions

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For gluons we have

Leading quark distributions

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QCD evolution

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Evolution equations

For flavor singlet combinations we have coupled equations:

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First momentum

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Data from CERN, SLAC & HERMES

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The isotopic SU(2) invariance of strong interactions,

We have two sum rules and can express sggdu AA and , trought and 8

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Experiment:

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are determined as matrix elements of conserved currents and do not depend on 2Q

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Remember:

Spin “puzzle”: s or G ????