Dark Neutrino interactions phase out the Hubble tension

TL;DR

This paper proposes new neutrino-dark matter interactions that modify the cosmic microwave background and matter power spectrum, reducing the Hubble tension and predicting observable signatures in future experiments.

Contribution

It introduces a novel neutrino interaction model that alleviates the Hubble tension without altering relativistic degrees of freedom.

Findings

Hubble tension reduced to ~2.1 sigma with the model

Predicts observable modifications in CMB B-modes

Enhances matter power spectrum through neutrino perturbations

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\le 0.12 h \ {\rm Mpc}^{-1} ) $ data, we demonstrate that in this model the Hubble tension reduces to approximately $ 2.1 \sigma$. Our model predicts potentially observable modifications of the CMB B-modes and the matter power spectrum that can be observed in future data sets.