  In the present work we approximate an ultrarelativistic jet by a homogeneous
beam of null matter with finite width. Then, we study the influence of this
beam over the space-time metric in the framework of higher-derivative gravity.
We find an exact shock wave solution of the quadratic gravity field equations
and compare it with the solution to Einstein's gravity. We show that the effect
of higher-curvature gravity becomes negligible at large distances from the beam
axis. We also observe that only the Ricci-squared term contribute to modify the
Einstein's gravity prediction. Furthermore, we note that this higher-curvature
term contribute to regularize the discontinuities associated to the solution to
Einstein's general relativity.
