The flavor universality of some mass splittings in hadrons

Abstract

The approximate chiral invariance of the two-flavor (QCD) is known to be spontaneously broken. This effect explains the relatively small pion mass and, as is widely believed, the mass splittings of would-be chiral partners — the hadrons of equal spin but opposite parity lying in one multiplet of the chiral symmetry. We present experimental evidences that in reality such mass splittings in the meson sector seem to be approximately flavor-independent in all cases where they can be tested experimentally — the spin 0 and 1. In addition, a partial flavor independence holds for spin-1/2 baryons (namely among states in which at least one of the quark is not u or d one). This property allow to predict masses and quantum numbers for 10 new hadrons. The given flavor-independence, if confirmed for higher spins, hints at the existence of universal scale Λ strong ~300 MeV in the strong interactions which, in contrast to Λ QCD , is flavor and scheme independent. Some manifestations of Λ strong are discussed.