We study the bispectrum in the Effective Field Theory of Large Scale Structure , consistently accounting for the effects of short-scale dynamics .
We begin by proving that , as long as the theory is perturbative , it can be formulated to arbitrary order using only operators that are local in time .
We then derive all the new operators required to cancel the UV-divergences and obtain a physically meaningful prediction for the one-loop bispectrum .
In addition to new , subleading stochastic noises and the viscosity term needed for the one-loop power spectrum , we find three new effective operators .
The three new parameters can be constrained by comparing with N -body simulations .
The best fit is precisely what is suggested by the structure of UV-divergences , hence justifying a formula for the EFTofLSS bispectrum whose only fitting parameter is already fixed by the power spectrum .
This result predicts the bispectrum of N -body simulations up to k _ { max } \approx 0.22 h \text { Mpc } ^ { -1 } at z = 0 , an improvement by nearly a factor of two as compared to one-loop standard perturbation theory .