Cai, Y (reprint author), Univ Chinese Acad Sci, Sch Phys, Beijing 100049, Peoples R China.
文章类型:
Article
英文摘要:
In low-energy effective string theory and modified gravity theories, the propagating speed c(T) of primordial gravitational waves may deviate from unity. We find that the steplike variation of c(T) during slow-roll inflation may result in an oscillating modulation to the B-mode polarization spectrum, which can hardly be imitated by adjusting other cosmological parameters, and the intensity of the modulation is determined by the dynamics of c(T). Thus provided that the foreground contribution is under control, high-precision cosmic microwave background (CMB) polarization observations will be able to put tight constraint on the variation of c(T), and so the corresponding theories.
