Quintessence axion dark energy and a solution to the hubble tension

Abstract

We present a model in which the question about a nature of the dark energy and the recently raised Hubble tension can be addressed at once. We consider the electroweak axion in the minimal supersymmetric standard model where the axion energy density is identified with the observed dark energy. Along with this, imposing a gauged Z10 symmetry makes it possible to have a gravitino dark matter whose mass amounts to ∼ O(1) GeV. We find that the gravitino with mass ∼ O(1) GeV can be a good candidate of a decaying dark matter of which decay after recombination can reconcile discrepancy in local measurements of the Hubble expansion rate H0 and that inferred from the cosmic microwave background observation.

Trans-Planckian censorship and inflation in grand unified theories

“…In closing, we mention that a similar mass range for gravitino DM as in our scenario has recently been identified in [88], however, for a completely different reason. The starting point of [88] is the extension of the MSSM by a supersymmetric axion multiplet that couples to the electroweak gauge bosons.…”

“…In closing, we mention that a similar mass range for gravitino DM as in our scenario has recently been identified in [88], however, for a completely different reason. The starting point of [88] is the extension of the MSSM by a supersymmetric axion multiplet that couples to the electroweak gauge bosons. This electroweak axion receives an extremely flat potential from SU (2) L instantons, which turns it into a quintessence field that serves as an explanation of dark energy [89,90].…”

“…This electroweak axion receives an extremely flat potential from SU (2) L instantons, which turns it into a quintessence field that serves as an explanation of dark energy [89,90]. The authors of [88] consider the decay of unstable gravitino dark matter into the degrees of freedom contained in the electroweak axion multiplet,G → a +ã, where a denotes the axion quintessence field andã is the corresponding axino. They argue that this decay represents a concrete realization of the decaying-DM mechanism proposed in [91] to resolve the so-called Hubble tension, i.e., to reconcile the CMB measurement of the Hubble parameter H 0 by the PLANCK satellite with the local H 0 value obtained via the cosmic distance ladder and time delay measurements of strongly lensed quasars [92].…”

“…They argue that this decay represents a concrete realization of the decaying-DM mechanism proposed in [91] to resolve the so-called Hubble tension, i.e., to reconcile the CMB measurement of the Hubble parameter H 0 by the PLANCK satellite with the local H 0 value obtained via the cosmic distance ladder and time delay measurements of strongly lensed quasars [92]. The main idea behind this solution to the Hubble tension is to slowly transfer energy from cold dark matter to massless radiation (i.e., axions in [88]) and a subdominant component of warm dark matter (i.e., axinos in [88]). The energy in radiation is then quickly redshifted away, which moves the onset of the dark-energy-dominated era to earlier times.…”

Vacuum arbitrariness and the Hubble tension

“…Among the late-time resolutions one may in particular note the phantom dark energy [5], the interacting dark energy [6] and the vacuum metamorphosis [7] models. On the other hand, the early-time modifications involve the early dark energy [8][9][10][11] and the scalar field [12][13][14] models (some specifically involving axions [15][16][17]). There are also alternative ideas like emerging spatial curvature due to nonlinear evolution of cosmic structures [18], large impact of non-Gaussian correlations between the short and long wavelength CMB modes [20], decaying dark matter [19], frame-dependent effective actions that mimic a cosmological constant [21] and interacting neutrinos [22].…”