Joint Theory Seminar
Speaker:Prashant Saraswat (Caltech)
Title: The Weak Gravity Conjecture, Effective Field Theory, and Inflation
Host: Verhaaren
Room: 432
Abstract: The Weak Gravity Conjecture (WGC) is a proposed constraint on theories with gauge fields and gravity, requiring the existence of light charged particles and/or imposing an upper bound on the field theory cutoff. If taken as a consistency requirement for effective field theories (EFTs), the WGC rules out possibilities for model-building including some models of cosmic inflation. Arguments for the WGC based on black hole properties appear at first to be universal in nature, independent of detailed UV physics. However, I will show how UV theories which satisfy the WGC may have low-energy EFT descriptions which badly violate it, while avoiding any pathologies in black hole physics. I'll argue that parametric violation of the WGC at low energies can be achieved only at the cost of non-minimal field content in the UV. I'll discuss the implications of these results for inflationary model-building and phenomenology. I also propose a new parametric constraint, much weaker than the WGC that should in fact apply to EFTs, motivated by black hole entropy bounds.
