Nuclear Physics B, cilt.1025, 2026 (SCI-Expanded, Scopus)
In this paper, a new class of two-variable Gegenbauer-type polynomials is introduced via a derivative-based construction. The definition incorporates an additional variable through finite sums involving higher-order derivatives of classical Gegenbauer polynomials with shifted parameters. Explicit representation and a generating function are obtained, leading to recurrence relations, differential relations, and an integral representation. Several addition formulas and properties involving Stirling numbers and power sums are also derived. Furthermore, new relations are established, leading to families of bilinear and bilateral generating functions. These results provide a systematic analytic description of the two-variable Gegenbauer polynomials.