In the cosmological concordance model, dark matter is assumed to be cold,
non-interacting and covariantly conserved. An interesting possibility to
consider is a violation of the third assumption in this simple picture,
namely the conversion of a small fraction of dark matter to an invisible
form of radiation.
So far, surprisingly little attention has been given to this option...
In my talk, will argue that the Hubble tension might be the signature of new physics in the early Universe. First, I will describe the conditions new physics has to satisfy to stand a chance of addressing the Hubble tension without compromising the fit of the CMB. Secondly, I will argue that this new physics could be related to a new phase of dark energy that decays in a first-order phase...
