2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/55820Modulo the ideal generated by the derivative fields, the normal ordered product of holomorphic fields in two-dimensional conformal field theory yields a commutative and associative algebra. The zero mode algebra can be regarded as a deformation of the latter. Alternatively, it can be described as an associative quotient of the algebra given by a modified normal ordered product. We clarify the relation of these structures to Zhu's product and Zhu's algebra of the mathematical literature.LaTeX (BibTeX), 6 pages, no figuresHigh Energy Physics - Theorytext