Nonlinear structure formation in Bound Dark Energy
  We study nonlinear structure formation in the Bound Dark Energy model (BDE),
where dark energy (DE) corresponds to a light scalar meson particle $\phi$
dynamically formed at a condensation energy scale $\Lambda_c$. The evolution of
this dark-energy meson is determined by the potential
$V(\phi)=\Lambda_c^{4+2/3}\phi^{-2/3}$, with a distinguishing phenomenology
from other quintessence scenarios. Particularly, the expansion rate of the
universe is affected not only at late times, but also when the condensation of
$\phi$ occurs, which in linear theory leads to an enhancement (with respect to
standard $\Lambda$CDM) of matter perturbations on small scales. We study how
much of this signature is still present at late times as well as the properties
of dark matter halos in the nonlinear regime through N-body simulations. Our
results show that nonlinear corrections wash out this feature from the matter
power spectrum even before DE becomes dominant. There is, however, a small but
clear suppression of the BDE spectrum of $2\%$ today on the largest scales due
to the distinct late-time dynamics of DE. The differences on the clustering
power between BDE and $\Lambda$CDM are reflected in the halo mass function,
where small halos are more abundant in BDE as opposed to large heavy
structures, whose formation is delayed because of the expansion history of the
universe. This result is well captured by the semi-analytical Sheth-Tormen
formula. However, despite these differences, the halo concentration parameter
is essentially the same in both models, which suggest that clustering inside
the halos decouple from the general expansion once the halos form.
