Feynman Propagators: Invariant Amplitude vs Loop Integrals

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The discussion clarifies the distinction between two types of Feynman propagators used in quantum field theory: \(\frac{i}{q^2-m^2}\) is specifically utilized for scalar particles, while \(\frac{i(p/+m)}{p^2-m^2}\) is designated for spin-1/2 particles, such as fermions. This differentiation is crucial for understanding their applications in invariant amplitude calculations and loop integrals. The participants confirm that the top propagator corresponds to scalar fields, while the bottom one pertains to fermionic fields.

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ryanwilk
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Hi, this is probably very simple but what is the difference between these two Feynman propagators:

\frac{i}{q^2-m^2}
\frac{i(p/+m)}{p^2-m^2}

E.g. Is one used for the invariant amplitude and the other for loop integrals? Or is one for a fermion and the other for a boson? =s

Thanks!
 
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The top one is for a scalar, the bottom one for a spin-1/2 particle.
 
Thank you!
 

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