Titlebook: What is the iε for the S-matrix?; Holmfridur Sigridar Hannesdottir,Sebastian Mizera Book 2022 The Author(s), under exclusive license to Sp

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Primer on the Analytic S-matrix, many of which have never appeared in the previous literature. In particular, one of the goals is to understand the ingredients leading to different ways of implementing . prescriptions for scattering amplitudes in perturbation theory. While rather elementary, the bubble example will allow us to dev

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,Singularities as?Classical Saddle Points,grals. Using the Schwinger-parameterized form, we explain how to determine their analytic properties in terms of algebraic conditions on the worldline action .. In particular, we find that branch cuts of the integral occur when ., and the causal branch is obtained by taking .. We analyze conditions

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Branch Cut Deformations,ut analyticity near the physical regions for . scattering of stable particles, and then move on to the analysis of concrete examples in later sections. These examples illustrate cases in which branch cuts run along the whole real .-axis, and they reveal two different situations: one when the branch

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Carcinogen

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Book 2022d exploiting consequences of unitarity, causality, and locality. It focuses on the question: Can the S-matrix be complexified in a way consistent with causality? The affirmative answer has been well understood since the 1960s, in the case of 2→2 scattering of the lightest particle in theories with a

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processes has significantly expanded over the past decade. Although well appreciated, the structural and biochemical complexity and the dynamic nature of the living matrix are still under extensive inv- tigation, yielding a growing number of methods with varying degree of sophistication and intricac

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