The tension between the value of the Hubble constant H _ { 0 } determined from local supernovae data and the one inferred from the cosmic microwave background based on the \Lambda CDM cosmological model may indicate the need for new physics .
Here , we show that this ‘ Hubble tension ’ can be resolved in models involving an effective energy flux from the matter sector into dark energy resulting naturally from a combination of unimodular gravity and an energy diffusion process .
The scheme is one where dark energy has the standard equation of state w = -1 .
This proposal provides an alternative phenomenological paradigm accounting for the observations , while offering a general framework to study diffusion effects coming from novel fundamental physical processes .