标题： 背景演化对弯曲子非高斯性的影响 显示英文标题

标题： Effect of Background Evolution on the Curvaton Non-Gaussianity

摘要： 我们研究了背景演化如何影响由曲率子生成的曲率扰动，假设曲率子势能可能略微偏离二次形式，并将背景流体密度参数化为 \( \text\{\rho \propto \} a^\text\{{-\alpha }\} \)，其中 \( a \) 是尺度因子，\alpha 取决于背景流体。结果表明，偏离二次情况的程度越大，曲率扰动对\alpha 的依赖性就越明显。我们还证明背景对非高斯性参数 \( f_\text\{NL\} \) 和 \( g_\text\{NL\} \) 有显著影响。 例如，如果在曲线子振荡开始时，势能存在 6 维度的贡献，占 5% 的比例，并且在曲线子衰变时其能量占总能量的 1%，我们发现物质主导和辐射主导背景之间存在 \Delta f_NL \sim \mathcal{O} (10) 和 \Delta g_NL \sim \mathcal{O} (10^4) 的变化。 此外，我们证明了 f_NL 和 g_NL 之间存在一种关系，可以用来探测曲线子势能的形式和背景流体的状态方程。 显示英文摘要

摘要： We investigate how the background evolution affects the curvature perturbations generated by the curvaton, assuming a curvaton potential that may deviate slightly from the quadratic one, and parameterizing the background fluid density as \rho\propto a^{-\alpha}, where a is the scale factor, and \alpha depends on the background fluid. It turns out that the more there is deviation from the quadratic case, the more pronounced is the dependence of the curvature perturbation on \alpha. We also show that the background can have a significant effect on the nonlinearity parameters f_NL and g_NL. As an example, if at the onset of the curvaton oscillation there is a dimension 6 contribution to the potential at 5 % level and the energy fraction of the curvaton to the total one at the time of its decay is at 1 %, we find variations \Delta f_NL \sim \mathcal{O}(10) and \Delta g_NL \sim \mathcal{O}(10^4) between matter and radiation dominated backgrounds. Moreover, we demonstrate that there is a relation between f_NL and g_NL that can be used to probe the form of the curvaton potential and the equation of state of the background fluid.