Positivity in electron-positron scattering:testing the axiomatic quantum field theory principles and probing the existence of UV states

• 来源期刊: 中国物理C（英文版）
• 年，卷（期）: 2021,（2）
• 所属期刊栏目: PARTICLES AND FIELDS
• 页码范围: 176-199
• 页数: 24页
• 语种: 英文
• DOI: 10.1088/1674-1137/abcd8c

摘要

We consider the positivity bounds on dimension-8 four-electron operators and study two related phe-nomenological aspects at future lepton colliders.First,if positivity is violated,probing such violations will revolu-tionize our understanding of the fundamental pillars of quantum field theory and the S-matrix theory.We observe that positivity violation at scales of 1-10 TeV can potentially be probed at future lepton colliders even if one as-sumes that dimension-6 operators are also present.Second,the positive nature of the dimension-8 parameter space often allows us to either directly infer the existence of UV-scale particles together with their quantum numbers or ex-clude them up to certain scales in a model-independent way.In particular,dimension-8 positivity plays an important role in the test of the Standard Model.If no deviations from the Standard Model are observed,it allows for simultan-eous exclusion limits on all kinds of potential UV-complete models.Unlike the dimension-6 case,these limits apply regardless of the UV model setup and cannot be removed by possible cancellations among various UV contributions.This thus consists of a novel and universal test to confirm the Standard Model.We demonstrate with realistic ex-amples how all the previously mentioned possibilities,including the test of positivity violation,can be achieved.Hence,we provide an important motivation for studying dimension-8 operators more comprehensively.