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m v2.05b - Bot T20 CW#61 - Fix errors for CW project (Reference before punctuation) |
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*<math>\beta(\alpha)=\frac{2\alpha^2}{3\pi}~,</math>
written in terms of the [[Fine-structure constant#In non-SI units|fine structure constant]] in natural units, {{math|''α'' {{=}} ''e''<sup>2</sup>/4π}}
This beta function tells us that the coupling increases with increasing energy scale, and QED becomes strongly coupled at high energy. In fact, the coupling apparently becomes infinite at some finite energy, resulting in a [[Landau pole]]. However, one cannot expect the perturbative beta function to give accurate results at strong coupling, and so it is likely that the Landau pole is an artifact of applying perturbation theory in a situation where it is no longer valid.
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