Title: Dark Matter Gravitational Clustering With a Long-Range Scalar Interaction

Abstract: We explore the possibility to improve the $\Lambda$CDM model at megaparsec scales by introducing a scalar interaction which increases the mutual gravitational attraction of dark matter particles. Using N-body simulations, we study the spatial distribution of dark matter particles and halos. We measure the effect of modifications in the Newton's gravity on properties of the two-point correlation function, the dark matter power spectrum and the cumulative halo mass function. The results look promising: the scalar interaction improves the agreement between theoretical predictions and observations at megaparsec scales without spoiling the $\Lambda$CDM successes at larger scales.