  We study the impact of full unitarity on the moment structure of forward
scattering amplitudes. We introduce the semiarcs, calculable quantities in the
EFT dispersively related to both real and imaginary parts of the UV amplitude
for a fixed number of subtractions. It is observed that large hierarchies
between consecutive moments are forbidden by unitarity. Bounds from full
unitarity compete with the ones stemming from convexity, and become more
important in EFTs where the loop expansion is more important than the
derivative expansion.
