A unified model of particle mass

The quark masses evaluated by the Particle Data Group are consistent with terms in a geometric progression of mass values descending from the Planck Mass. The common ratio of the sequence is 2/pi. The quarks occupy the 'principal' levels of the mass spectrum, characterised by a new quantum number, n. Hadrons occupy mass sub-levels, characterised by fractional values of n. The quark masses of the model are used to formulate hadron mass construction equations based on the masses of neutral precursor particles. Hadron mass partnerships occur, in which mass differences arising from differences in spin, isospin and isospin projection are equal to the masses of principal levels. Mass partnerships also occur between charged leptons and pseudoscalar mesons.