PIRSA:21020017 Scientific Series Quantum Fields and Strings

DOI10.48660/21020017

Series: Quantum Fields and Strings

Riva, F. (2021). Positive Moments for Scattering Amplitudes . Perimeter Institute. https://pirsa.org/21020017

Riva, Francesco. Positive Moments for Scattering Amplitudes . Perimeter Institute, Feb. 09, 2021, https://pirsa.org/21020017 

@misc{ pirsa_PIRSA:21020017,
  doi = {10.48660/21020017},
  url = {https://pirsa.org/21020017},
  author = {Riva, Francesco},
  keywords = {Quantum Fields and Strings},
  language = {en},
  title = {Positive Moments for Scattering Amplitudes },
  publisher = {Perimeter Institute},
  year = {2021},
  month = {feb},
  note = {PIRSA:21020017 see, \url{https://pirsa.org}}
}

Abstract

I will discuss the conditions satisfied by the 2 → 2 scattering amplitude in unitarity and causal theories, presenting a simple formulation in term of moments of a positive measure. I will identify complete subsets of two-sided constraints, suitable to bound Effective Field Theories (EFTs) at any finite order in the energy expansion. I will also discuss  the importance of IR loop effects on these bounds. A consequence of this study is that EFTs in which the scattering amplitude in some regime grows in energy faster than E6 (e.g. higher spin particles with masses smaller than their inverse size) cannot be UV-completed.

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