Abstract
We replace general relativity (GR) and the cosmological constant (Lambda ) in the standard cosmology (SM–GR–Lambda –CDM) with a Lorentz gauge theory of gravity (LGT) and show that the standard model (SM) neutrinos can be the cold dark matter (CDM) because (1.) the expansion of the universe at early times is not as sensitive to the amount of radiation as in the SM–GR–Lambda –CDM and (2.) in LGT there exists a spin-spin long-range force that is very stronger than the Newtonian gravity and interacts with any fermion including neutrinos. Assuming that neutrinos as heavy as 1 eV are the cold dark matter, the lower bound on the dimensionless coupling constant of LGT is derived to be 10^{-7} which is small enough to be consistent with the upper bound that can be placed by the electroweak precision tests. We also show that the vacuum energy does not gravitate in LGT and a decelerating universe shifts spontaneously to an accelerating one right at the moment that we expect. Therefore, current observations can be explained in our cosmological model (SM–LGT) with lesser assumptions than in the SM–GR–Lambda –CDM.
Highlights
Some cosmological observations are only an indication of a certain expansion profile
A successful model is not the one that has the required expansion profile but instead is the one whose assumptions – predictions – regarding the matter, the radiation, and the vacuum energy are confirmed through other independent observations
The two points coincide with when the standard cosmology shifts from radiation-dominated to matter-dominated era and when the decelerating universe jumps into an accelerating one. At the former point, the standard cosmology puts a stringent constraint on the neutrino radiation
Summary
Some cosmological observations are only an indication of a certain expansion profile. A certain type of expansion is needed at early times to explain the observations of the primordial light elements These observations can be used to draw a theory-independent experimental expansion profile for the universe. At late times, a decelerating universe spontaneously shifts to an accelerating one, i.e. it is not necessary to fine-tune the magnitude of the cosmological constant in order to reach the needed expansion profile. This model only needs an input about the cold matter – whose value is obtained through independent observations. In this paper we show that if neutrinos have a mass of 1eV and the dimensionless coupling constant of LGT is 6 orders of magnitude smaller than the electroweak couplings, cold neutrino dark matter is a viable scenario and the spin-spin force has negligible effects in the electroweak precision tests
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