  Motivated by an apparent puzzle of the light-front vacua incompatible with
the axial anomaly, we have considered the two-dimensional massless Schwinger
model for an arbitrary interpolating angle of the quantization surface. By
examining spectral deformation of the Dirac sea under an external electric
field semiclassically, we have found that the axial anomaly is quantization
angle independent. This indicates an intricate nontrivial vacuum structure
present even in the light-front limit.
