The University of Southampton

SHEP Friday Seminar - Sebastian Schenk, Towards the Breakdown of Perturbation Theory at High Energies - Event

10th of December, 2021  @  13:00 - 14:15

Event details

Calculations of high-energy processes involving the         production of a large number of particles in weakly-coupled quantum field theories have previously sparked ideas towards        the need for novel non-perturbative behavior or even new          physical phenomena. In this talk, I will review some           scenarios where already tree-level computations may enter          the regime of large-order perturbation theory and therefore          require a careful investigation. I will argue that in scalar

          quantum field theories with a unique global minimum, where
          suitably resummed perturbative expansions are expected to
          capture all relevant physical effects, perturbation theory
          may still suffer from severe shortcomings in the high-energy
          regime. As an example, I will consider the computation of
          multiparticle threshold amplitudes in scalar field theories
          with (higher-order) self-interactions and demonstrate they
          these may violate unitarity of the quantum theory, even
          after the resummation of all leading quantum corrections.

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