# IR-safe and UV-safe integrands in the EFTofLSS with exact time dependence

## TL;DR

This paper develops IR- and UV-safe integrands for the one-loop power spectrum in the EFTofLSS with exact time dependence, improving numerical efficiency and accuracy for cosmological predictions.

## Contribution

It introduces a formulation of the one-loop power spectrum integrand that is free of IR and UV divergences, extending previous approximations to exact time dependence.

## Key findings

- IR and UV divergences cancel in the integrand
- The IR- and UV-safe integrand improves computational efficiency
- Enhanced agreement with N-body simulations at two-loop level

## Abstract

Because large-scale structure surveys may very well be the next leading sources of cosmological information, it is important to have a precise understanding of the cosmological observables; for this reason, the Effective Field Theory of Large-Scale Structure (EFTofLSS) was developed. So far, most results in the EFTofLSS have used the so-called Einstein-de Sitter approximation, an approximation of the time dependence which is known to be accurate to better than one percent. However, in order to reach even higher accuracy, the full time dependence must be used. The computation with exact time dependence is sensitive to both infrared (IR) and ultraviolet (UV) effects in the loop integrands, and while these effects must cancel because of diffeomorphism invariance, they make numerical computation much less efficient. We provide a formulation of the one-loop, equal-time exact-time-dependence power spectrum of density perturbations which is manifestly free of these spurious IR and UV divergences at the level of the integrand. We extend our results to the total matter mode with clustering quintessence, show that IR and UV divergences cancel, and provide the associated IR- and UV-safe integrand. This also establishes that the consistency conditions are satisfied in this system. We then use our one-loop result to do an improved precision comparison of the two-loop dark-matter power spectrum with the Dark Sky N-body simulation.