2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/228160We discuss the flavor content of the nucleon in an unquenched quark model in which the effects of quark-antiquark pairs (up, down and strange) are taken into account in an explicit form. It is shown that the inclusion of quark-antiquark pairs leads to an excess of anti-d over anti-u quarks in the proton and to a large contribution of orbital angular momentum to the spin of the proton.4 pages, invited talk at XIII Mexican School of Particles and Fields, San Carlos, Sonora, Mexico, October 6-11, 2008, to be published in AIP Conference ProceedingsNuclear Theorytext