Simple Gradient Flow Equation for the Bounce Solution
  Motivated by the recent work of Chigusa, Moroi, and Shoji, we propose a new
simple gradient flow equation to derive the bounce solution which contributes
to the decay of the false vacuum. Our discussion utilizes the discussion of
Coleman, Glaser, and Martin and we solve a minimization problem of the kinetic
energy while fixing the potential energy. The bounce solution is derived as a
scale-transformed of the solution of this problem. We also show that the
convergence of our method is robust against a choice of the initial
configuration.
