Renormalized Perturbation Theory at Field-level: the LSS bootstrap in GridSPT
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| Format: | Preprint |
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2025
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| author | Peron, Matteo Nishimichi, Takahiro Pietroni, Massimo Taruya, Atsushi |
| author_facet | Peron, Matteo Nishimichi, Takahiro Pietroni, Massimo Taruya, Atsushi |
| contents | We present a first step toward field-level cosmological inference beyond the standard $Λ$CDM model, focusing on optimizing precision tests in the nonlinear regime of large-scale structure (LSS). As an illustrative case, we study the model-independent ``bootstrap'' coefficient of the second-order perturbation theory (PT) kernel for matter in real space, which we use as a proxy for new physics effects in the nonlinear sector. We discuss in details the ultraviolet (UV) cutoff dependence induced by discretizing fields on a grid, which requires proper renormalization to eliminate grid artifacts. We formulate a Wilsonian perturbative framework in which the evolution from a UV theory defined at a high cutoff $Λ_\text{uv}$ down to lower cutoffs is computed analytically, even beyond the validity of a derivative expansion. Within this framework, we develop an extended version of the GridSPT code incorporating the bootstrap parameterization and demonstrate how cutoff-independent predictions can be achieved through the inclusion of appropriate counterterms. We validate our approach at third- and fifth-order in PT, emphasizing the importance of higher-derivative contributions for unbiased parameter extraction. Our framework is readily extendable to biased tracers and redshift-space distortions. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2506_07105 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Renormalized Perturbation Theory at Field-level: the LSS bootstrap in GridSPT Peron, Matteo Nishimichi, Takahiro Pietroni, Massimo Taruya, Atsushi Cosmology and Nongalactic Astrophysics We present a first step toward field-level cosmological inference beyond the standard $Λ$CDM model, focusing on optimizing precision tests in the nonlinear regime of large-scale structure (LSS). As an illustrative case, we study the model-independent ``bootstrap'' coefficient of the second-order perturbation theory (PT) kernel for matter in real space, which we use as a proxy for new physics effects in the nonlinear sector. We discuss in details the ultraviolet (UV) cutoff dependence induced by discretizing fields on a grid, which requires proper renormalization to eliminate grid artifacts. We formulate a Wilsonian perturbative framework in which the evolution from a UV theory defined at a high cutoff $Λ_\text{uv}$ down to lower cutoffs is computed analytically, even beyond the validity of a derivative expansion. Within this framework, we develop an extended version of the GridSPT code incorporating the bootstrap parameterization and demonstrate how cutoff-independent predictions can be achieved through the inclusion of appropriate counterterms. We validate our approach at third- and fifth-order in PT, emphasizing the importance of higher-derivative contributions for unbiased parameter extraction. Our framework is readily extendable to biased tracers and redshift-space distortions. |
| title | Renormalized Perturbation Theory at Field-level: the LSS bootstrap in GridSPT |
| topic | Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2506.07105 |