Theory HEP Seminar

Landau-Ginzburg orbifolds and symmetries of K3 CFTs

Sarah Harrison

Harvard

Moonshine is a mysterious relationship in mathematics between finite groups and modular forms, which appears to have deep connections to physics and string theory. I will first review the well-understood case of monstrous moonshine, a connection between the modular J-function and the largest sporadic finite simple group. Then I will discuss "Umbral moonshine," a new moonshine phenomenon which relates mock modular forms to automorphism groups of Niemeier lattices. I will explain how Umbral moonshine has connections to symmetries of sigma models arising from string compactification on K3 surfaces. Finally, I will discuss work to elucidate this connection by studying K3 CFTs which can be realized as IR limits of Landau-Ginzburg models.