Title: Primordial Nucleosynthesis as a Test of the Friedmann Equation in the Early Universe Show Chinese title

Title: 原初核合成作为早期宇宙中弗里德曼方程的检验

Abstract: In the standard hot big bang model, the expansion of the early universe is given by the Friedmann equation with an energy density dominated by relativistic particles. Since in a variety of models this equation is altered, we introduce modifications in the Friedmann equation and show that we can constrain them using big bang nucleosynthesis data. When there is no neutrino/antineutrino asymmetry these modifications are tightly bounded but in presence of an asymmetry the bounds become much looser. As an illustration, we apply our results to a model where the second and third families couple to gravity differently than the first family (non-universal gravity). Show Chinese abstract

Abstract: 在标准热大爆炸模型中，早期宇宙的膨胀由弗里德曼方程给出，其能量密度由相对论粒子主导。 由于在各种模型中该方程会发生变化，我们引入了弗里德曼方程的修改，并表明可以利用大爆炸核合成数据对其进行约束。 当没有中微子/反中微子不对称性时，这些修改受到严格限制，但在存在不对称性的情况下，限制会变得宽松得多。 作为示例，我们将结果应用于一个模型，其中第二代和第三代粒子与引力的耦合方式不同于第一代（非普遍引力）。