Please use this identifier to cite or link to this item: http://arks.princeton.edu/ark:/88435/dsp01p8418q82n
 Title: On the Uniqueness and Consistency of Scattering Amplitudes Authors: Rodina, Laurentiu Advisors: Arkani-Hamed, Nima Contributors: Physics Department Keywords: BCFWgauge invariancelocalityscattering amplitudeunitarity Subjects: Particle physics Issue Date: 2017 Publisher: Princeton, NJ : Princeton University Abstract: In this dissertation, we study constraints imposed by locality, unitarity, gauge invariance, the Adler zero, and constructability (scaling under BCFW shifts). In the first part we study scattering amplitudes as the unique mathematical objects which can satisfy various combinations of such principles. In all cases we find that locality and unitarity may be derived from gauge invariance (for Yang-Mills and General Relativity) or from the Adler zero (for the non-linear sigma model and the Dirac-Born-Infeld model), together with mild assumptions on the singularity structure and mass dimension. We also conjecture that constructability and locality together imply gauge invariance, hence also unitarity. All claims are proved through a soft expansion, and in the process we end re-deriving the well-known leading soft theorems for all four theories. Unlike other proofs of these theorems, we do not assume any form of factorization (unitarity). In the second part we show how tensions arising between gauge invariance (as encoded by spinor helicity variables in four dimensions), locality, unitarity and constructability give rise to various physical properties. These include high-spin no-go theorems, the equivalence principle, and the emergence of supersymmetry from spin 3/2 particles. We also complete the fully on-shell constructability proof of gravity amplitudes, by showing that the improved bonus'' behavior of gravity under BCFW shifts is a simple consequence of Bose symmetry. URI: http://arks.princeton.edu/ark:/88435/dsp01p8418q82n Alternate format: The Mudd Manuscript Library retains one bound copy of each dissertation. Search for these copies in the library's main catalog: catalog.princeton.edu Type of Material: Academic dissertations (Ph.D.) Language: en Appears in Collections: Physics