Zero average values of cosmological perturbations as an indispensable   condition for the theory and simulations
  We point out a weak side of the commonly used determination of scalar cosmological perturbations lying in the fact that their average values can be nonzero for some matter distributions. It is shown that introduction of the finite-range gravitational potential instead of the infinite-range one resolves this problem. The concrete illustrative density profile is investigated in detail in this connection. 
Maxim Eingorn, Maxim Brilenkov, Branislav Vlahovic
astro-ph.CO gr-qc hep-th