Hybrid Quarkonia with Dynamical Sea Quarks

We present a first dynamical lattice calculation with 2 flavours for bottomonium states with an additional gluonic excitation. Using improved actions for the quarks and gauge fields at a lattice spacing of $a \approx 0.1$ fm, we estimate 11.02(18) GeV for the energy of the lowest lying $b\bar bg$-hybrid. In a parallel quenched simulation we demonstrate explicitly that vacuum polarisation effects are less than 10% of the splitting with the ground state.