The global Gan-Gross-Prasad conjecture for Fourier-Jacobi periods on unitary groups

We prove the Gan-Gross-Prasad conjecture for Fourier-Jacobi periods on unitary groups and an Ichino-Ikeda type refinement. Our strategy is based on the comparison of relative trace formulae formulated by Liu. We develop the full coarse spectral and geometric expansions of the relative trace formulae, and compute relevant spectral terms via zeta integrals and truncated periods. We compare all geometric terms and characterize the local geometric comparison in terms of spectral data.