  In the decay process of metastable vacua in quantum field theories, the
bounce solution, a classical solution in Euclideanized theories, is helpful in
calculating the decay rate. Recently, the bounce solution with a conical
singularity has attracted wide attention and revealed physical importance. In
this paper, we discuss the bubble of nothing solution, which describes the
decay process of a five-dimensional Kaluza-Klein vacuum, and study the
consequence of including conical singularity. We found that the bounce solution
with singularities has a higher decay rate than those without. This effect
suggests that a singular solution can play a dominant role in vacuum decay of
theories with compact internal space. We also discuss the enhanced decay rate
from a thermodynamic perspective.
