Striking regularity in meson and baryon production rates in e+e− annihilations

It is shown that e+e− data on the production rates of all particles (apart from pions) belonging to the SU (3) nonets of the pseudoscalar and vector mesons and to the octet and decuplet of the baryons are determined only by particle spins, isospins and their masses. Contrary to the general belief and popular models, such as the Jetset model, the 2J + 1 spin counting factor works perfectly. The meson and baryon production rates at the Z0 pole at LEP as a function of particle mass squared lie on the one universal curve described by a simple formula 〈N(particle)〉 = 2J+12Im+1a exp(−bM2) with parameters a = 11.28 ± 0.31 and b = 3.872 ± 0.027 (GeVc2)−2 and X2NDF = 1510, where Im is the isospin for baryons or the modified isospin Im for mesons introduced in this paper. A similar universal dependence with the same value of the slope b is observed at PETRA and PEP energies.