Spontaneous Creation of the Brane World and Direction of the Time Arrow
  In this note we consider the spontaneous creation of the brane world in five-dimensional space with nondynamical external four-form field via spherically asymmetric bounce solution. We argue that spherically asymmetric bounce suggests several inequivalent directions of the time arrow upon the analytic continuation to the space-time with Lorentzian signature. It it shown that S-branes in the imaginary time emerge naturally upon the particular continuation. 
A.Gorsky