Particles and Shells

The current understanding of particle masses in terms of quarks and their binding energy is not satisfactory. Both in atoms and in nuclei the organizing principle of stability is the shell structure, while this does not seem to play any role for particles. In order to explore the possibility that shells might also be relevant at this inner level of aggregation, atomic and nuclear stability are expressed by "stablines", alignments of the 1/3 power of the total number of constituents of the most stable configurations. Could similar patterns be found in the particle spectrum? By analyzing the distribution of particle lifetimes as a function of mass, stability peaks are recognized for mesons and for baryons and indeed the cube roots of their masses follow two distinct stablines. Such alignments would be a strong indication that the particles themselves are shell structured assuming only that each constituent contributes a constant amount to the total mass. This is incompatible with the prevalent view that the partons---real physical constituents seen in deep-inelastic scattering experiments---are the quarks. The mass of the Bc predicted by interpolation with the meson stabline is 7.4 ±0.2 GeV. On the baryon stabline two missing states are predicted at 3.9 and 7.6 GeV.