Hoyle band and α condensation in 12C

The excited states in C-12 are investigated by using an extended version of the so-called Tohsaki-Horiuchi-Schuck-Ropke (THSR) wave function, where both the 3 alpha condensate and Be-8 + alpha cluster asymptotic configurations are included. A new method is also used to resolve spurious continuum coupling with physical states. I focus on the structures of the "Hoyle band" states (0(2)(+), 2(2)(+), and 4(2)(+)), which were recently observed above the Hoyle state, and of the 0(3)(+) and 0(4)(+) states, which were also quite recently identified in experiment. Their resonance parameters and decay properties are reasonably reproduced. All these states have dilute density structure of the 3 alpha or Be-8 + alpha clusters with larger root mean square radii than that of the Hoyle state. The Hoyle band is not simply considered to be the Be-8(0(+)) + alpha rotation as suggested by previous cluster model calculations, nor to be a rotation of a rigid-body triangle-shaped object composed of the 3 alpha particles. This is mainly due to the specificity of the Hoyle state, which has the 3 alpha condensate structure and gives rise to the 0(3)(+) state with a prominent Be-8(0(+)) + alpha structure as a result of very strong monopole excitation from the Hoyle state.