2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/45840We analyze the $γγ\to π^0π^0$ and $γγ\to π^+π^-$ reactions using the master formula approach to chiral symmetry breaking. The pertinent vacuum correlators are estimated at tree level, and the results are compared with one- and two-loop chiral perturbation theory. The Compton scattering amplitude and the pion polarizabilities are also discussed.LaTex, 11 pages, 5 PostScript figures (uuencoded)High Energy Physics - PhenomenologyNuclear Theorytext