- #1
dman12
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Hello. I am doing some reading on QED and am getting a bit confused on the different conventions used. In Matthew Schwartz's book we have the Lagrangian given as:
LQED = -¼ FμνFμν + iψ*γμ(∂μ + ieAμ)ψ - V(ψ*ψ)
And the path integral factor is exp(iS).
In another text, however, I see the QED lagrangian given as:
LQED = ¼ FμνFμν + ψ*γμ(∂μ + eAμ)ψ - V(ψ*ψ)
And the exponential factor in the path integral is exp(-S).
How can I see that these two conventions are physically the same? In particular, what is the difference between using exp(iS) and exp(-S) in the path integral?
Thanks!
LQED = -¼ FμνFμν + iψ*γμ(∂μ + ieAμ)ψ - V(ψ*ψ)
And the path integral factor is exp(iS).
In another text, however, I see the QED lagrangian given as:
LQED = ¼ FμνFμν + ψ*γμ(∂μ + eAμ)ψ - V(ψ*ψ)
And the exponential factor in the path integral is exp(-S).
How can I see that these two conventions are physically the same? In particular, what is the difference between using exp(iS) and exp(-S) in the path integral?
Thanks!