标题： 高曲率弦背景下的张量扰动 显示英文标题

标题： Tensor perturbations in high-curvature string backgrounds

摘要： 我们推导了宇宙背景中张量扰动演化的广义方程，考虑了高曲率贡献以及弦框架中对标量场的树级耦合。 该方程通过在$\alpha'$的一级展开来扰动引力-标量弦有效作用量获得。 $\alpha'$校正可以修改低能扰动谱，但当弦框架中的背景曲率保持恒定时，修正被证明很小。 显示英文摘要

摘要： We derive a generalized equation for the evolution of tensor perturbations in a cosmological background, taking into account higher-curvature contributions and a tree-level coupling to the dilaton in the string frame. The equation is obtained by perturbing the gravi-dilaton string effective action, expanded up to first order in $\alpha'$. The $\alpha'$ corrections can modify the low-energy perturbation spectrum, but the modifications are shown to be small when the background curvature keeps constant in the string frame.