On the internal consistency of holographic dark energy models

Abstract

Holographic dark energy (HDE) models, underpinned by an effective quantum field theory(QFT) with a manifest UV/IR connection, have become convincing candidates forproviding an explanation of the dark energy in the universe. On the other hand, themaximum number of quantum states that a conventional QFT for a box of sizeL is capable of describing relates to those boxes which are on the brink of experiencing asudden collapse to a black hole. Another restriction on the underlying QFT is that the UVcut-off, which cannot be chosen independently of the IR cut-off and thereforebecomes a function of time in a cosmological setting, should stay the largestenergy scale even in the standard cosmological epochs preceding a dark energydominated one. We show that, irrespective of whether one deals with the saturatedform of HDE or takes a certain degree of non-saturation in the past, the aboverestrictions cannot be met in a radiation dominated universe, an epoch in the history ofthe universe which is expected to be perfectly describable within conventionalQFT.