“…The generalization of the standard SU(3) Gell-Mann-Okubo mass formula [1] to higher symmetry groups, e.g., SU(4) and SU (5), became a natural subject of investigation after the discovery of the fourth and fifth quark flavors in the mid-70's [2]. Attempts have been made in the literature to derive such a formula, either quadratic or linear in mass, by a) using group theoretical methods [3,4,5,6,7], b) generalizing the perturbative treatment of U(3) × U(3) chiral symmetry breaking and the corresponding Gell-Mann-Oakes-Renner relation [8] to U(4)×U(4) [9,10], c) assuming the asymptotic realization of SU(4) symmetry in the algebra [A α , A β ] = if αβγ V γ (where V α , A β are vector and axial-vector charges, respectively) [11], d) extending the Weinberg spectral function sum rules [13] to accommodate the higher symmetry breaking effects [12], and e) applying alternative methods, such as the linear mass spectrum for meson multiplets 1 [14,15]. In the following 2 , η, η s , η c , η b , K, D, D s , B, B s , B c stand for the masses of the nn (n ≡ u or d), ss, cc, b b, sn, cn, cs, bn, bs, bc mesons, respectively 3 The linear mass relations…”