On the Hubble expansion in a Big Bang quantum cosmology

Abstract

The Hubble expansion of the Universe is considered in the classical limit of a Big Bang quantum cosmology. In an IR-consistent coupling to the bare cosmological constant, we infer a dark energy as a relic of the Big Bang by loss of time-translation invariance on a Hubble time-scale. This dark energy is identified with the trace J of the Schouten tensor permitting an analytic solution $H\left(z\right)$. Anchored by the Baryonic Accoustic Oscillations, JCDM predicts a Hubble constant $H_0=\sqrt{6/5}{H}_0^{\Lambda }$ alleviating $H_0$-tension between the Local Distance Ladder and $H_0^{\Lambda }$ in ΛCDM, whose dark energy Λ is a constant. Emulated by $w\left(a\right)\Lambda$CDM, a CAMB analysis shows a JCDM fit to the Planck 2018 $C_l^{TT}$ power spectrum on par with ΛCDM with small positive curvature consistent with Planck-ΛCDM with no extra relativistic degrees of freedom. In late-time cosmology, JCDM is also consistent with the BAO recently measured by DESI. JCDM offers a novel framework to address $H_0$-tension, predicting background quantities consistent with the uncertainties in BAO measurements and early-Universe observations. It predicts a deceleration parameter $q_0\simeq -1$, that may be tested with upcoming low-redshift galaxy surveys.