Bounds on the species scale and Emergent Strings

by Dr Max Wiesner (Center of Mathematical Sciences and Applications, Harvard University)

Wednesday 21 Jun 2023, 14:30 → 16:00 Europe/Berlin

SR2 (Building 2a)

Abstract: The species scale serves as a UV cut-off in the gravitational sector of an effective field theory. Since the spectrum of light states varies as a function of the moduli fields the species scale is in general moduli-dependent. In the first part of this talk, I will discuss the moduli-dependence of this species scale and derive bounds for the species scale that are valid at any point in field space, including interior points. I will further use the species scale to constrain slowly-varying positive potentials and argue that the Emergent String Conjecture (ESC) predicts a bound on the scalar potential that remarkably coincides with the prediction of the TransPlanckian Censorship Conjecture. The ESC is a powerful conjecture stating that in asymptotic weak-coupling limits of gravitational theories a tower of states becomes massless corresponding either to a KK tower or to the tower of excitations of a fundamental string. In the second part of my talk I will argue that universal properties of black holes indeed predict that the leading tower of light states in a gravitational theory is either KK- or string-like thereby providing a bottom-up argument for a central statement of the ESC.