Asymptotic Freedom in QCD
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From the Bjorken scaling of the nucleon structure functions, we learn that the hadronic constituents probed at small distance or at high energy behave as if they were almost noninteracting or ‘free’. We are confronted with an apparent paradox, since in quantum field theory virtual particles exchanged between partons can have arbitrarily high momenta, quantum fluctuations associated with them naturally occur at short distances. Why do these fluctuations turn themselves off, and the partons behave as if they were free at high energy, whereas at low energy they are strongly bound? How can a model of noninteracting quarks be reconciled with a force that is extremely strong in other circumstances?
KeywordsRenormalization Group Feynman Rule Vacuum Polarization Renormalization Group Equation Vertex Function
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