2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/191660New explicit expressions are derived for the one-loop two-point Feynman integral with arbitrary external momentum and masses $m_1^2$ and $m_2^2$ in D dimensions. The results are given in terms of Appell functions, manifestly symmetric with respect to the masses $m_i^2$. Equating our expressions with previously known results in terms of Gauss hypergeometric functions yields reduction relations for the involved Appell functions that are apparently new mathematical results.19 pages. To appear in Journal of Mathematical PhysicsHigh Energy Physics - TheoryMathematical PhysicsClassical Analysis and ODEstext