Big Steve and the State of the Universe

R. P. Woodard

doi:10.3390/sym15040856

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arXiv · 2303.05111

Big Steve and the State of the Universe

R. P. Woodard

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Abstract

I share some reminiscences of the late Steven Weinberg. Then I discuss a topic in quantum field theory which he taught me: the role of state wave functionals in deriving the $i\epsilon$ term of the Feynman propagator when using the functional formalism. This is perhaps a curiosity for in-out scattering amplitudes on flat space backgrounds, but it is has much greater significance for the in-in amplitudes of the Schwinger-Keldysh formalism in cosmology. It also touches on the fate, about which Weinberg wondered, of the large logarithms one sometimes finds in quantum corrections from inflationary particle production.

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R. P. Woodard. 2023-03-09. Big Steve and the State of the Universe. https://doi.org/10.3390/sym15040856

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