Measurement of the ratio of the production cross sections times branching fractions of B_c^± → J/ψπ^± and B^± → J/ψK^± and B(B_c^± → J/ψπ^±π^±π^∓)/B(B_c^± → J/ψπ^±) in pp collisions at √s=7 Tev Journal Article