%0 Journal Article %T K-mouflage Cosmology: Formation of Large-Scale Structures %+ Institut de Physique Théorique - UMR CNRS 3681 (IPHT) %A Brax, Philippe %A Valageas, Patrick %Z ANR 2010 BLANC 0413 01 %Z 23 pages %< avec comité de lecture %@ 1550-7998 %J Physical Review D %I American Physical Society %V 90 %P 023508 %8 2014 %D 2014 %Z 1403.5424 %R 10.1103/PhysRevD.90.023508 %Z PACS numbers: 98.80.-k %Z Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO]Journal articles %X We study structure formation in K-mouflage cosmology whose main feature is the absence of screening effect on quasi-linear scales. We show that the growth of structure at the linear level is both affected by a new time dependent Newton constant and a friction term which depend on the background evolution. These combine with the modified background evolution to change the growth rate by up to ten percent since $z\sim 2$. At the one loop level, we find that the non-linearities of the K-mouflage models are mostly due to the matter dynamics and that the scalar perturbations can be treated at tree level. We also study the spherical collapse in K-mouflage models and show that the critical density contrast deviates from its $\Lambda$-CDM value and that, as a result, the halo mass function is modified for large masses by an order one factor. Finally we consider the deviation of the matter spectrum from $\Lambda$-CDM on non-linear scales where a halo model is utilised. We find that the discrepancy peaks around $1\ h{\rm Mpc}^{-1}$ with a relative difference which can reach fifty percent. Importantly, these features are still true at larger redshifts, contrary to models of the chameleon-$f(R)$ and Galileon types. %G English %2 https://cea.hal.science/cea-02929292/document %2 https://cea.hal.science/cea-02929292/file/Bra1.pdf %L cea-02929292 %U https://cea.hal.science/cea-02929292 %~ CEA %~ CNRS %~ OPENAIRE %~ DSM-IPHT %~ CEA-DRF %~ ANR %~ GS-MATHEMATIQUES %~ GS-PHYSIQUE