  Coulomb breakup strengths of 11Li into a three-body 9Li+n+n system are
studied in the complex scaling method. We decompose the transition strengths
into the contributions from three-body resonances, two-body ``10Li+n'' and
three-body ``9Li+n+n'' continuum states. In the calculated results, we cannot
find the dipole resonances with a sharp decay width in 11Li. There is a low
energy enhancement in the breakup strength, which is produced by both the two-
and three-body continuum states. The enhancement given by the three-body
continuum states is found to have a strong connection to the halo structure of
11Li. The calculated breakup strength distribution is compared with the
experimental data from MSU, RIKEN and GSI.
