Identify for $f(\infty)+f(-\infty)$ in quantum field theory
49348
S. Weinberg, “The Quantum theory of fields: Foundations” (1995), Eq. (9.2.15)
107686
Proof that the gamma function is an extension of the factorial function
87951
Normalizable wavefunction that does not vanish at infinity
145183
finding $\int_0^\infty \dfrac{dx}{1+x^4}$ through complex analysis
78008
A conjectured closed form of $\int\limits_0^\infty\frac{x-1}{\sqrt{2^x-1}\ \ln\left(2^x-1\right)}dx$
13018
Why is $1^{\infty}$ considered to be an indeterminate form
31919
What can we say about the inner product $\langle f(t),f'(t) \rangle$?
21917
Mathematical Prerequisites for QFT
156727
A step in the proof of Characterization of $W^{1,\infty}$
111128
The Duals of $l^\infty$ and $L^{\infty}$
111775
$\int_{-\infty}^{+\infty} e^{-x^2} dx$ with complex analysis
82659
How to write $\delta (f(x))$ in terms of $\delta (x)$?
79307
How to analyze $\sup_{x>0}|e^xf(x)| < \infty$ and $\sup_{n\in\mathbb{N}} |f^{(n)}(0)|< \infty$?
89295
The interpretation of mass in quantum field theories
60796
Integrating $\int^{\infty}_0 e^{-x^2}\,dx$ using Feynman's parametrization trick
100004
Differentiating $e^x$ from first principles using limits.
89528
Formalizing Quantum Field Theory