Emergent family of Tsallis entropies from the $q$-deformed combinatorics

Abstract: We revisit the derivation of a formula for the $q$-generalised multinomial coefficient rooted in the $q$-deformed algebra, a foundational framework in the study of nonextensive statistics. Previous approximate expressions in the literature diverge as $q$ approaches 2 (or 0, depending on convention). In contrast, our derived formula provides an exact, smooth function for all real values of $q$, expressed as an infinite series expansion involving Tsallis entropies with sequential entropic indices, coupled with Bernoulli numbers. This formulation is achieved through the analytic continuation of the Riemann zeta function, stemming from the $q$-deformed factorials. Our formula thus offers a distinctive characterisation of Tsallis entropy within the $q$-deformed combinatorics. Throughout this exploration, we also highlight a symmetry within the $q$-deformed theory that links different values of the entropic parameter. Furthermore, we discuss extending our results to encompass more general, affinity-sensitive cases, building on the previously established framework of affinity-based extended entropy.