Bremsstrahlung function from Goldstone bosons in AdS$_2$
We study quantum field theory on the AdS$_2$ worldsheet of the fundamental string dual to the half-BPS Wilson line of $\mathcal{N}=4$ super Yang-Mills. We consider a recently proposed gauge-fixed string fluctuation Lagrangian around the AdS$_2$ minimal surface, and focus on the nonlinearly realized $SO(6)/SO(5)$ symmetry. The boundary two-point function of the associated tilt operators, whose normalization coefficient is proportional the Bremsstrahlung function, can be related to the bulk two-point function of the broken-symmetry Noether current through the boundary operator expansion. We evaluate the one-loop diagrams contributing to the current correlator, discussing the role of dimensional regularization and recovering the known strong-coupling correction to the Bremsstrahlung function directly from AdS$_2$ worldsheet quantum field theory.