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Results tagged with perturbation-theory
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user 24699
Perturbation theory refers to methods for understanding physical systems by treating them as small modifications to exactly solvable systems.
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Minus sign in perturbative expansion via Green's function (Schwartz QFT)?
In Schwartz's QFT textbook Section 3.5, the Lagrangian for the graviton $$\mathcal{L}=-\frac{1}{2}h\Box h+\frac{1}{3}\lambda h^3+Jh$$ with EOM $\Box h-\lambda h^2-J=0$ is perturbatively expanded in $h …
- 365
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Minus sign in perturbative expansion via Green's function (Schwartz QFT)?
Figured this out as I was typing the question...
The d'Alembertian $\Box_y=\partial_y\partial_y$, so to 'swap' it with an adjacent element, it requires two uses of integration by parts.
That is, $\i …
- 365