Symmetries of mesons after unbreaking of chiral symmetry and their string interpretation

Understand

Using the chirally invariant overlap Dirac operator we remove its lowest-lying quasizero modes from the valence quark propagators and study evolution of isovector mesons with J=1.

• At the truncation level about 50 MeV SU(2)_L \times SU(2)_R and U(1)_A symmetries get restored.
• However, we observe a degeneracy not only within the chiral and U(1)_A multiplets, but also a degeneracy of all possible chiral multiplets, i.e., the observed quantum levels have a symmetry larger than U(2)_L \times U(2)_R and their energy does not depend on the spin orientation of quarks and their parities.
• We offer a possible interpretation of these energy levels as the quantum levels of the dynamical QCD string.