Calculating Vacuum Energy as a Possible Explanation of the Dark Energy
  We carried out a study of the properties of the $\lambda \phi^4$ field
solutions. By constructing Gaussian wave packets to calculate the $S$ matrix,
we show that the probability of the vacuum unbroken state transfers to the
broken state is about $10^{-52}$. After adding this probability restriction
condition as modulation factor in the summation of vacuum energy, we thus get a
result that the vacuum energy density is about $10^{-47}GeV^4$, which is exact
same as the observed dark energy density value, and maybe served as a possible
explanation of the dark energy. Also our result shows that the vacuum energy
density is proportional to the square of the universe's age, which fits the
Dirac large numbers hypothesis.
