  Motivated by a recent controversy on a possible quantum phase in thin films
of relatively clean superconductors under an out-of-plane magnetic field, the
quantum fluctuation effects on the phase diagram and the resistivity are
reexamined. It is argued that most of features seen in the corresponding
resistivity data in relatively clean systems reported recently are explained
within the present theory, and that the fan-shaped resistivity curves,
suggestive of the presence of a superconductor to insulator transition at zero
temperature, in the vortex liquid regime is a consequence of the insulating
behavior of the Aslamasov-Larkin fluctuation conductivity in the quantum
regime.
