Abstract
New interactions of neutrinos can stop them from free streaming even after the weak interaction freeze-out. This results in a phase shift in the cosmic microwave background (CMB) acoustic peaks which can alleviate the Hubble tension. In addition, the perturbations in neutrinos do not decay away on horizon entry and contribute to metric perturbation enhancing the matter power spectrum. We demonstrate that this acoustic phase shift can be achieved using new interactions of standard left-handed neutrinos with dark matter without changing the number of effective relativistic degrees of freedom. Using Planck CMB and the WiggleZ galaxy survey $(k\ensuremath{\le}0.12h\text{ }\text{ }{\mathrm{Mpc}}^{\ensuremath{-}1})$ data, we demonstrate that in this model the Hubble tension reduces to approximately $2.1\ensuremath{\sigma}$. Our model predicts potentially observable modifications of the CMB $B$ modes and the matter power spectrum that can be observed in future datasets.
Highlights
The values of the Hubble constant (H0) inferred from cosmic microwave background (CMB) anisotropies (67.5Æ 0.6 km s−1 Mpc−1 [1,2]) and baryon acoustic oscillations (BAO) measurements (66.98 Æ 1.18 km s−1 Mpc−1 [3,4,5,6,7,8]) are significantly smaller than the measurements from observations of the nearby Universe using the distance ladder (74.03 Æ 1.42 km s−1 Mpc−1 [9,10,11])
We propose a new class of solutions in which new physics (NP) solves the Hubble tension by inducing changes in the phase shift φ
We have proposed a qualitatively new framework that ameliorates the Hubble tension by primarily using the phase shift in the acoustic oscillations of the primordial plasma
Summary
The values of the Hubble constant (H0) inferred from cosmic microwave background (CMB) anisotropies (67.5Æ 0.6 km s−1 Mpc−1 [1,2]) and baryon acoustic oscillations (BAO) measurements (66.98 Æ 1.18 km s−1 Mpc−1 [3,4,5,6,7,8]) are significantly smaller than the measurements from observations of the nearby Universe using the distance ladder (74.03 Æ 1.42 km s−1 Mpc−1 [9,10,11]). Pushed higher, to reconcile CMB/BAO or acoustic H0 with local H0 [17,21,22,25,26,27,28,30,31,33,36,37,38,40,41,42,43,44,48,51] Since in these solutions the early expansion history of the Universe [HðzÞ for z > zÃ] is unchanged, rà remains unaltered. All of the solutions that have been proposed so far to alleviate the Hubble tension fall into the above two classes and, in particular, keep the acoustic scale at recombination θà 1⁄4 rÃ=DA fixed even after accommodating a larger Hubble constant
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