EXOTIC MESONS FROM QUANTUM CHROMODYNAMICS WITH IMPROVED GLUON AND QUARK ACTIONS ON THE ANISOTROPIC LATTICE

Abstract

Hybrid (exotic) mesons, which are important predictions of quantum chromodynamics (QCD), are states of quarks and antiquarks bound by excited gluons. First principle lattice study of such states would help us understand the role of "dynamical" color in low energy QCD and provide valuable information for experimental search for these new particles. In this paper, we apply both improved gluon and quark actions to the hybrid mesons, which might be much more efficient than the previous works in reducing lattice spacing error and finite volume effect. Quenched simulations were done at β=2.6 and on a ξ=3 anisotropic 12 ³×36 lattice using our PC cluster. We obtain 2013±26±71 MeV for the mass of the 1 ^-+ hybrid meson [Formula: see text] in the light quark sector, and 4369±37±99 MeV in the charm quark sector; the mass splitting between the 1 ^-+ hybrid meson [Formula: see text] in the charm quark sector and the spin averaged S-wave charmonium mass is estimated to be 1302±37±99 MeV. As a byproduct, we obtain 1438±32±57 MeV for the mass of a P-wave 1 ⁺⁺[Formula: see text] or [Formula: see text] meson and 1499±28±65 MeV for the mass of a P-wave 1 ⁺⁺[Formula: see text] meson, which are comparable to their experimental value 1426 MeV for the f ₁(1420) meson. The first error is statistical, and the second one is systematical. The mixing of the hybrid meson with a four quark state is also discussed.