Probability distribution of the vacuum energy density
  As the vacuum state of a quantum field is not an eigenstate of the
Hamiltonian density, the vacuum energy density can be represented as a random
variable. We present an analytical calculation of the probability distribution
of the vacuum energy density for real and complex massless scalar fields in
Minkowski space. The obtained probability distributions are broad and the
vacuum expectation value of the Hamiltonian density is not fully representative
of the vacuum energy density.
