Exotic hybrid mesons from lattice QCD

Abstract:

The fact that gluons carry color charge suggests that they, like quarks, could be ``valence'' constituents of hadrons. In other words, we expect that the spectrum of QCD should contain glueballs and hybrids, or particles with both quarks and gluons as valence constituents. Hybrid mesons can have exotic quantum numbers, or J^PC combination not possible with a quark-antiquark state. I will discuss efforts by the MILC collaboration to determine the mass of the exotic J^PC=1^-+ hybrid meson. We use both quenched and full lattice QCD with improved Kogut-Susskind fermions. Extrapolation of our quenched results to the physical light quark mass allows comparison with experimental candidates for such states.