2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/214819We show that the semi-leptonic decay B+ -> pi+ pi- l+ ν_l can be used as a source of information for two-pion distribution amplitudes. The connection between these amplitudes and the B-meson decay width is achieved by the light cone sum rule method. We show the relevant distribution amplitudes and give the formula for the decay width.8 pages, 4 figures, LaTeX, two minor typos in the text corrected, two references updated. Version to be published in EJPCHigh Energy Physics - Phenomenologytext