In every text book Ive seen, in order to show that QCD is asymptotically free the first coefficient of the beta function is calculated and shown to be negative. However, neglecting the terms that are higher order in the coupling is only allowed if we know the coupling is small, and we dont know when the coupling is small until we've calculated the beta function! This reasoning seems circular to me. Any explanation of this would be appreciated.(adsbygoogle = window.adsbygoogle || []).push({});

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# Asymptotic freedom

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