2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/49592We investigate the transverse momentum effects in $γγ\toπ^+π^-$ at moderately large total center of mass energy $\sqrt{s}$ in the modified perturbative approach. The calculation of the differential cross section using different approximations shows that the inclusion of $k_\perp$ in the quark and gluon propagators cannot lead to a considerable improvement of the theoretical prediction.6 pages, 3 figures, Talk given at the XVII Autumn School, ``QCD: Perturbative or Nonperturbative'', Lisbon, Portugal, 29. Sept. - 4. Oct. 1999, to appear in the proceedings. Missing figure addedHigh Energy Physics - Phenomenologytext