Chiral multiplets of excited mesons

It is shown that experimental meson states with spins J=0,1,2,3 in the energy range 1.9 - 2.4 GeV obtained in recent partial wave analysis of proton-antiproton annihilation at LEAR remarkably confirm all predictions of chiral symmetry restoration. Classification of excited \ q q mesons according to the representations of chiral U(2)L \× U(2)R group is performed. There are two important predictions of chiral symmetry restoration in highly excited mesons: (i) physical states must fill out approximately degenerate parity-chiral multiplets; (ii) some of the physical states with the given I,JPC are members of one parity-chiral multiplet, while the other states with the same I,JPC are members of the other parity-chiral multiplet. For example, while some of the excited \ρ(1,1⁻⁻) states are systematically degenerate with a₁(1,1⁺⁺) states forming (0,1)+(1,0) chiral multiplets, the other excited \ρ(1,1⁻⁻) states are degenerate with h₁(0,1⁺⁻) states ((1/2,1/2) chiral multiplets). Hence, one of the predictions of chiral symmetry restoration is that the combined amount of a₁(1,1⁺⁺) and h₁(0,1⁺⁻) states must coincide with the amount of \ρ(1,1⁻⁻) states in the chirally restored regime. It is shown that the same rule applies (and experimentally confirmed) to many other meson states.