Toward an accurate Dark Matter power spectrum beyond BAO scales

We propose a new approximated expression for non-linear Dark Matter power spectrum much beyond BAO scales. The proposed expression agrees with the result of N-body simulation with the accuracy better than 2 % up to k=1.0 [h/Mpc] and k=0.7 [h/Mpc] at z=3.0 and z=1.0, respectively. Even at z=0.35, the accuracy remains within 10 % up to k=0.8 [h/Mpc]. In doing so, we used an approximation for the kernel functions used in the Standard Perturbation Theory (SPT) which is also used to prove the Reg PT proposed by Bernardeau et al. (2011).