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Paper IPM / P / 15109  


Abstract:  
A perturbative description of Large Scale Structure is a cornerstone of our understanding of the observed distribution of matter in the universe. Renormalization is an essential and deï¬ning step to make this description physical and predictive. Here we introduce a systematic renormalization procedure, which neatly associates counterterms to the UVsensitive diagrams order by order, as it is commonly done in quantum ï¬eld theory. As a concrete example, we renormalize the oneloop power spectrum and bispectrum of both density and velocity. In addition, we present a series of results that are valid to all orders in perturbation theory. First, we show that while systematic renormalization requires temporally nonlocal counterterms, in practice one can use an equivalent basis made of local operators. We give an explicit prescription to generate all counterterms allowed by the symmetries. Second, we present a formal proof of the wellknown general argument that the contribution of short distance perturbations to large scale density contrast Î´ and momentum density Ï(k) scale as k2 and k, respectively. Third, we demonstrate that the common practice of introducing counterterms only in the Euler equation when one is interested in correlators of Î´ is indeed valid to all orders.
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