Oliver Schlotterer: From loop integrals to modular graph forms

Wednesday 1 Apr 2026, 13:30 → 14:30 Europe/Stockholm

Å92110 (Ångströmslaboratoriet)

The low-energy expansion of loop-level string amplitudes features discontinuities in Mandelstam invariants to all orders in alpha’ which reflect matrix elements of higher-derivative operators Tr(D^{2k} F^n) and D^{2k} R^n in the effective action. The UV divergences of the one-loop matrix elements at fixed order in alpha’ were observed in 2107.08009 to encode the cusp asymptotics of modular graph forms, namely the non-holomorphic modular forms that govern the analytic-in-Mandelstam parts of one-loop string amplitudes. In joint work with Enrico and Michele, we generalize this link to obtain the cusp asymptotics of *arbitrary* modular graph forms (also those beyond massless string amplitudes) from the UV regime of stringy generating series of one-loop Feynman integrals.