Nonperturbative δN formalism
| Autor: | Shailee V. Imrith, Arttu Rajantie, David J. Mulryne |
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| Rok vydání: | 2018 |
| Předmět: | |
| Zdroj: | Physical Review D. 98 |
| ISSN: | 2470-0029 2470-0010 |
| DOI: | 10.1103/physrevd.98.043513 |
| Popis: | We revisit the question of how to calculate correlations of the curvature perturbation, $\ensuremath{\zeta}$, using the $\ensuremath{\delta}N$ formalism when one cannot employ a truncated Taylor expansion of $N$. This problem arises when one uses lattice simulations to probe the effects of isocurvature modes on models of reheating. Working in real space, we use an expansion in the cross-correlation between fields at different positions and present simple expressions for observables such as the power spectrum and the reduced bispectrum, ${f}_{\mathrm{NL}}$. These take the same form as those of the usual $\ensuremath{\delta}N$ expressions, but with the derivatives of $N$ replaced by nonperturbative $\ensuremath{\delta}N$ coefficients. We test the validity of this expansion and, when compared to others in the literature, argue that our expressions are particularly well suited for use with simulations. |
| Databáze: | OpenAIRE |
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