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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…

General Relativity and Quantum Cosmology · Physics 2012-12-03 Naonori S. Sugiyama , Toshifumi Futamase

Constraining cosmological parameters from large-scale structure observations requires precise and accurate tools to compute its properties. While perturbation theory (PT) approaches can serve this purpose, exploration of large parameter…

Cosmology and Nongalactic Astrophysics · Physics 2024-03-12 Ken Osato , Takahiro Nishimichi , Atsushi Taruya , Francis Bernardeau

In a recent Letter, Dornheim et al. [PRL 125, 085001 (2020)] have investigated the nonlinear density response of the uniform electron gas in the warm dense matter regime. More specifically, they have studied the cubic response function at…

A new computational scheme for the nonlinear cosmological matter power spectrum (PS) is presented. Our method is based on evolution equations in time, which can be cast in a form extremely convenient for fast numerical evaluations. A…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Stefano Anselmi , Massimo Pietroni

We consider one-loop corrections to the bispectrum and skewness of cosmological density fluctuations induced by gravitational evolution. As has been established by comparison with numerical simulations, tree-level perturbation theory (PT)…

Astrophysics · Physics 2009-10-28 Roman Scoccimarro

We develop a framework to compute the redshift space power spectrum (PS), with kernels beyond Einstein-de Sitter (EdS), that can be applied to a wide variety of generalized cosmologies. We build upon a formalism that was recently employed…

Cosmology and Nongalactic Astrophysics · Physics 2021-04-16 Alejandro Aviles , Georgios Valogiannis , Mario A. Rodriguez-Meza , Jorge L. Cervantes-Cota , Baojiu Li , Rachel Bean

We develop a new approach to study the nonlinear evolution in the large-scale structure of the Universe both in real space and in redshift space, extending the standard perturbation theory of gravitational instability. Infinite series of…

Astrophysics · Physics 2008-11-26 Takahiko Matsubara

Nonlinear effects are crucial in order to compute the cosmological matter power spectrum to the accuracy required by future generation surveys. Here, a new approach is presented, in which the power spectrum, the bispectrum and higher order…

Astrophysics · Physics 2009-11-13 Massimo Pietroni

Cosmological linear perturbation theory predicts that the peculiar velocity $V(x)$ and the matter overdensity $\delta(x)$ at a same point $x$ are statistically independent quantities, as log as the initial density fluctuations are random…

Astrophysics · Physics 2009-10-31 Naoki Seto

We present the leading order non-linear density and velocity power spectra in the complete form; previous studies have omitted the vector- and tensor-type perturbations simultaneously excited by the scalar-type perturbation in nonlinear…

Cosmology and Nongalactic Astrophysics · Physics 2016-04-22 Jai-chan Hwang , Donghui Jeong , Hyerim Noh

In this paper the non-linear effect of massive neutrinos on cosmological structures is studied in a conceptually new way. We have solved the non-linear continuity and Euler equations for the neutrinos on a grid in real space in $N$-body…

Cosmology and Nongalactic Astrophysics · Physics 2022-03-02 Jeppe Dakin , Jacob Brandbyge , Steen Hannestad , Troels Haugbølle , Thomas Tram

Perturbation theory makes it possible to calculate the probability distribution function (PDF) of the large scale density field in the small variance limit. For top hat smoothing and scale-free Gaussian initial fluctuations, the result…

Astrophysics · Physics 2015-06-24 S. Colombi , F. Bernardeau , F. R. Bouchet , L. Hernquist

Density matrix perturbation theory [Phys. Rev. Lett. Vol. 92, 193001 (2004)] provides an efficient framework for the linear scaling computation of response properties [Phys. Rev. Lett. Vol. 92, 193002 (2004)]. In this article, we generalize…

Computational Physics · Physics 2009-11-11 Anders M. N. Niklasson , Valery Weber , Matt Challacombe

Precise understanding of nonlinear evolution of cosmological perturbations during inflation is necessary for the correct interpretation of measurements of non-Gaussian correlations in the cosmic microwave background and the large-scale…

General Relativity and Quantum Cosmology · Physics 2013-05-30 Naonori S. Sugiyama , Eiichiro Komatsu , Toshifumi Futamase

We compute the non-Gaussian contribution to the covariance of the matter power spectrum at one-loop order in Standard Perturbation Theory (SPT), and using the framework of the effective field theory (EFT) of large scale structure (LSS). The…

Cosmology and Nongalactic Astrophysics · Physics 2016-06-08 Daniele Bertolini , Katelin Schutz , Mikhail P. Solon , Jonathan R. Walsh , Kathryn M. Zurek

We provide a comparison between the matter bispectrum derived with different flavours of perturbation theory at next-to-leading order and measurements from an unprecedentedly large suite of $N$-body simulations. We use the $\chi^2$…

Cosmology and Nongalactic Astrophysics · Physics 2022-03-14 Davit Alkhanishvili , Cristiano Porciani , Emiliano Sefusatti , Matteo Biagetti , Andrei Lazanu , Andrea Oddo , Victoria Yankelevich

Realistic models of particle physics include many scalar fields. These fields generically have nonminimal couplings to the Ricci curvature scalar, either as part of a generalized Einstein theory or as necessary counterterms for…

Cosmology and Nongalactic Astrophysics · Physics 2010-09-27 David I. Kaiser , Audrey T. Todhunter

We study the energy level spacing of perturbed conformal minimal models in finite volume, considering perturbations of such models that are massive but not necessarily integrable. We compute their spectrum using a renormalization group…

Statistical Mechanics · Physics 2015-05-18 G. P. Brandino , R. M. Konik , G. Mussardo

Based on the Effective Field Theory (EFT) of cosmological perturbations, we explicitly clarify the pathology in nonsingular cubic Galileon models and show how to cure it in EFT with new insights into this issue. With the least set of EFT…

General Relativity and Quantum Cosmology · Physics 2017-06-13 Yong Cai , Hai-Guang Li , Taotao Qiu , Yun-Song Piao

Ensembling is now recognized as an effective approach for increasing the predictive performance and calibration of deep networks. We introduce a new approach, Parameter Ensembling by Perturbation (PEP), that constructs an ensemble of…

Machine Learning · Computer Science 2020-10-27 Alireza Mehrtash , Purang Abolmaesumi , Polina Golland , Tina Kapur , Demian Wassermann , William M. Wells