AI 中文总结
该研究针对轴子暴胀的强反作用 regime，通过两种微扰控制量化方法发现大耦合下存在扩展温和反作用 regime，且 CMB 非高斯性约束给出了轴子-规范场耦合与哈勃参数乘积的上限。
AI 中文摘要
我们研究轴子暴胀中的强反作用 regime，在此 regime 中，由赝标量相互作用 $\frac{\beta}{4 M_p} \tilde{F} F$ 产生的阿贝尔规范场带来的摩擦，与哈勃摩擦相当。与规范场相关的非线性动力学使该 regime 在现象学上极具研究价值，但用微扰方法研究却极为困难。通过以下两种方式量化对谱反作用的直接影响来评估微扰控制：（i）包含轴子梯度的一阶梯度展开形式；（ii）单圈 in-in 计算，我们发现在大耦合 $\beta$ 下存在一个扩展的温和反作用 regime，其粒子产生参数 $\xi$ 相对较大且近乎恒定。顺便指出，CMB 非高斯性约束对暴胀期间轴子-规范场耦合与哈勃参数的乘积施加了一个通用上限：$\beta H/M_p < 1.4 \times 10^{-3}$，该上限与轴子势的选择无关。
英文摘要
We study the strong backreaction regime in axion inflation, in which the friction from Abelian gauge fields generated via the pseudo-scalar interaction $\fracβ{4 M_p} ϕF {\tilde F}$ is comparable to Hubble friction. The non-linear dynamics associated with the gauge fields render this regime phenomenologically particularly interesting, but also notoriously difficult to study with perturbative methods. Quantifying the perturbative control through the direct impact on the spectral backreaction using (i) a first-order gradient-expansion formalism including axion gradients, and (ii) a one-loop in-in calculation, we discover an extended mild backreaction regime at large couplings $β$, with a relatively large, nearly constant particle production parameter $ξ$. In passing, we point out that CMB non-Gaussianity bounds impose a general upper limit on the product of axion gauge field coupling and Hubble parameter during inflation, $βH/M_p < 1.4\cdot 10^{-3}$, independently of the choice of the axion potential.
Comments32 pages, 9 Figures
