- #1

LCSphysicist

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- Homework Statement
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- Relevant Equations
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If we add to the Lagrangian of SM a term $$\frac{{\phi}F_{\mu v}F^{\mu v}}{F_{\phi}}$$

How does the fine structure constant ##\alpha## changes as $$\phi = A_\phi cos(m_{\phi} t)$$?

I am having some hard time to finding out where i should start. I remember see the strucutre constant arrising when we evaluate vertices on feynman diagrams for QED interactions... But i am too ignorant to know how to proceed..