Positivity Bounds on Effective Field Theories: Galileon Theories as a Case Study

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Jalali, Mohammad Hossein | 2018

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 51661 (05)
University: Sharif University of Technology
Department: Physics
Advisor(s): Torabian, Mahdi
Abstract:
Effective field theory is a practical method for model building and explaining experimental/observational data. These theories are constructed based on knowing low energy degrees of freedom and symmetries (accidental or fundamental). By construction, these theories are applicable up to a cut-off scale and their predictions beyond that are not reliable. For applications to higher energies a UV completion is needed through which modifications are applied or new heavy degrees of freedom are introduced. In order to complete a theory in a Wilsonian approach, scattering amplitudes must satisfy some constraints. These constraints are derived from basic assumptions like Lorentz invariance, unitarity, analyticity and being power law in momenta. In this dissertation, we study these constraints in details and apply them to Gialileon theory. We study what conditions it must satisfy in order to be UV completed in a more fundamental theory
Keywords:
Positivity Bounds ; Analiticity ; Locality ; Unitarity ; Crossing Symmetry