Bounds on Species Scale and the Distance Conjecture

Understand

The species scale $\Lambda_s\leq M_{pl}$ serves as a UV cutoff in the gravitational sector of an EFT and can depend on the moduli of the theory as the spectrum of the theory varies.

• We argue that the dependence of the species scale $\Lambda_s (\phi)$ on massless (or light) modes $\phi^i$ satisfies $M_{pl}^{d-2} |\Lambda_s'/\Lambda_s|^2< \mathcal{O}(1)$.
• This bound is true at all points in moduli space including also its interior.
• The argument is based on the idea that the short distance contribution of massless modes to gravitational terms in the EFT cannot dramatically affect the black hole entropy.