| 書(shū)目名稱(chēng) | What is the iε for the S-matrix? | | 編輯 | Holmfridur Sigridar Hannesdottir,Sebastian Mizera | | 視頻video | http://file.papertrans.cn/1028/1027822/1027822.mp4 | | 概述 | Provides a pedagogical introduction to the analytic properties of the S-matrix.Reviews the rich literature on singularities of scattering amplitudes.Presents a new prescription for analytically contin | | 叢書(shū)名稱(chēng) | SpringerBriefs in Physics | | 圖書(shū)封面 |  | | 描述 | .This book provides a modern perspective on the analytic structure of scattering amplitudes in quantum field theory, with the goal of understanding and 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 mass gap at low momentum transfer, where the S-matrix is analytic everywhere except at normal-threshold branch cuts. We ask whether an analogous picture extends to realistic theories, such as the Standard Model, that include massless fields, UV/IR divergences, and unstable particles. Especially in the presence of light states running in the loops, the traditional iε prescription for approaching physical regions might break down, because causality requirements for the individual Feynman diagrams can be mutually incompatible. We demonstrate that such analyticity problems are not in contradiction with unitarity. Instead, they should be thought of as finite-width effects that disappear in the idealized 2→2 scattering amplitudes with no unstabl | | 出版日期 | Book 2022 | | 關(guān)鍵詞 | Scattering Matrix; Feynman integrals; QFT and Causality; Anomalous thresholds; Landau equation; Schwinger | | 版次 | 1 | | doi | https://doi.org/10.1007/978-3-031-18258-7 | | isbn_softcover | 978-3-031-18257-0 | | isbn_ebook | 978-3-031-18258-7Series ISSN 2191-5423 Series E-ISSN 2191-5431 | | issn_series | 2191-5423 | | copyright | The Author(s), under exclusive license to Springer Nature Switzerland AG 2022 |
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