  By using a powerful reductive perturbation technique, or a multiscale
analysis, a generic Kadomtsev-Petviashvili evolution equation governing the
propagation of femtosecond spatiotemporal optical solitons in quadratic
nonlinear media beyond the slowly varying envelope approximation is put
forward. Direct numerical simulations show the formation, from adequately
chosen few-cycle input pulses, of both stable line solitons (in the case of a
quadratic medium with normal dispersion) and of stable lumps (for a quadratic
medium with anomalous dispersion). Besides, a typical example of the decay of
the perturbed unstable line soliton into stable lumps for a quadratic nonlinear
medium with anomalous dispersion is also given.
