A Viable Alternative To The Standard Model Of Cosmology?

The lamda CDM model also known as the Standard Model of Cosmology, assumes a cosmological constant in the equations of general relativity and cold dark matter (more accurately, any dark matter that doesn't have relativistic velocities).

So far, it has been the reigning model in terms of fits to the data, but there are a variety of tensions with the data. As the paper explains:

During the last two decades observational cosmology has entered an era of unprecedented precision. Cosmic microwave background (CMB) measurements, baryon acoustic oscillations (BAO) and observations of Type Ia Supernovae have shown very good agreement with the predictions of the standard cosmological model (ΛCDM) consisting of dark energy in the form of a cosmological constant Λ and cold dark matter (CDM). 

However this agreement is not perfect: the Planck CMB data are in tension with low redshift data such as cluster counts, redshift space distortions (RSD), weak lensing data and local measurements of the Hubble constant, H₀. More specifically, the low redshift probes point towards a lower rate of structure growth (equivalently, a lower σ8) than the Planck results for the base ΛCDM would prefer. The most significant tensions are the ones coming from the cluster and weak lensing data.

Now, researchers have come up with a model that fits all the data that the lamda CDM model fits just as well, while significantly resolving the tensions that it has with the data.

They use a quintessence model, in lieu of a cosmological constant (i.e. they treat dark energy as an energy field rather than as part of the formula for the law of gravity), and in the model, quintessence "couples" with dark matter, i.e. quintessence a.k.a. dark energy interacts with dark matter in a very particular way.  In this model, dark energy can not transfer energy to dark matter, and visa versa, but momentum is exchanged between dark energy and dark matter in an energy neutral exchange.

This tweak to the Standard Model of Cosmology eases the tensions between the Standard Model of Cosmology and the data without detracting from any of its strengths.

It is probably too early to know if there is some hidden flaw in this new model, but it is one of the most promising developments in cosmology for quite a while.