Speaker
Description
$\Lambda CDM$ is increasingly challenged by observations in the late-time Universe. Here we consider unparticle cosmology for its potential to alleviate some of these issues. Unparticles offer a scale invariant contribution by an extra parameter $\delta$, here studied for $\delta \in [-6,1]$ (corresponding to scaling dimension $d_u \in [-2,3/2]$). For most values of $\delta$, the model predicts the distant future to be Minkowski or stable de Sitter, the latter in common with $\Lambda CDM$. For some $\delta \approx -3$, it predicts a diverging $H(z)$ in the future of universe accompanied by a turning point at some $-1<$$z<0$. However, in a detailed confrontation with $H(z)$-data within the radius of convergence of this model, the data show a clear preference for the holographic limit $\delta=-2$ without any additional assumptions. This pointer to holography is remarkable because of recent studies suggesting it may ameliorate $H_0$-tension, even though in unparticle cosmology this limit fails to resolve this tension evidenced by a pronounced gap in our $qQ$-diagram.
