2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/179354The generalized *-products, or the $*_N$-products, appear both in the one-loop effective action of noncommutative Yang-Mills theories and in the coupling of a closed string to N open strings on a disk when the D-brane world-volume is noncommutative. Factorization of the string amplitudes provides a uniform understanding of the $*_N$-products and a hint to obtain a simple, explicit formula (in the momentum space) for arbitrary N in the non-Abelian case. Possible extension to a more general ${}_M *_{N}$-product in the M-loop context is discussed.11 pages, 3 figures; v2. a reference added, typos correctedHigh Energy Physics - Theorytext