Miao LiUniversity of Science and Technology of China, HefeiWei SongInstitute of Theoretical Physics,Academia SinicaYushu SongInstitute of Theoretical Physics,Academia Sinica, Beijing
We quantize a string in the de Sitter background, and we find that the mass spectrum is modified by a term which is quadratic in oscillating numbers, and also proportional to the square of the Hubble constant.