Emergent strings and backreacting branes in the non-supersymmetric landscape

by Ivano Basile (UMONS)

Main/0-174 - Auditorium (MPP)

Main/0-174 - Auditorium


also via Zoom:

Recent considerations based on the swampland program dovetail nicely with dimensional arguments, hinting at string-scale supersymmetry breaking as the natural arena to investigate the underpinnings of string theory and its connections to real-world phenomenology. We explore the dramatic consequences of this scenario and its relations with a number of interconnected swampland proposals. We focus on the USp(32) and U(32) orientifolds of the type IIB and type 0B strings, as well as the SO(16) x SO(16) projection of the exceptional heterotic string, which provide non-tachyonic settings with no moduli directly in ten dimensions. While deceptively innocuous at the level of worldsheet perturbation theory, dynamical gravitational tadpoles backreact on spacetime in a dramatic fashion. We discuss how branes can tame this effect to a certain extent, finding that spacetime universally breaks down at a finite distance, ending in a strongly coupled, highly curved singularity. Remarkably, the dynamics of branes in these settings remains consistent among different complementary regimes despite the absence of supersymmetric protection. We connect the resulting picture with the weak gravity, de Sitter and distance conjectures, which are realized via novel mechanisms and provide tantalizing hints for a candidate S-dual heterotic construction of the USp(32) orientifold with “brane supersymmetry breaking”.