Dark energy and particle mixing

Abstract

We show that the vacuum condensate due to particle mixing is responsible of a dynamically evolving dark energy. In particular, we show that values of the adiabatic index close to −1 for vacuum condensates of neutrinos and quarks imply, at the present epoch, contributions to the vacuum energy compatible with the estimated upper bound on the dark energy.

Quantum gravity, flavour vacua and supersymmetry

“…Indeed, such four fermion attractive terms have been discussed in connection with chiral symmetry breaking in the early universe, and induced dark energy in the late eras, but from a different perspective than ours [16]. In our approach, as we have discussed, neutrino condensates in the flavour vacuum do also contribute to the late-times Universe acceleration, in the form of a dark energy fluid [8,12], but the equations of state of fermions and bosons are different, which is an additional way for breaking supersymmetry in initially supersymmetric models, as those obtained from realistic string theories.…”

“…This is not surprising, since we know that in a supersymmetric field-theory model the state with the lowest energy is unique, and corresponds to the usual vacuum |0 , for which 0|T 00 |0 = 0, all other states having positive energies. The difference in energy of the "flavour vacuum" from the mass-eigenstate one is due to the condensation of massive flavoured particle-antiparticle states [8,9,12]. The choice of this vacuum leads therefore to a breaking of supersymmetry, in a novel way, which is explored further by considering the equations of state w B,F = p B,F /ρ B,F of the individual bosonic (B) and fermionic (F) fluid constituents [10]:…”

Cosmological Effects of Quantum Vacuum Condensates

“…where λ = B, F, i = 1, 2 and the reference frame k = (0, 0, |k|) has been adopted [59][60][61][62][63][64]. The Bogoliubov coefficients for mixed bosons are,…”

Fermion Interactions, Cosmological Constant and Space-Time Dimensionality in a Unified Approach Based on Affine Geometry

“…The other problem that arises here is how to generate the 4-fermion interaction from first principles and how to get its contributions to the cosmological constant. An approach where cosmological constant comes out from fermion condensations is discussed in [18].…”