摘要
We study adiabatic regularization of a coupling massless scalar field in general spatially flat Robertson-Walker(RW)spacetimes.For the conformal coupling,the 2nd-order regularized power spectrum and 4th-order regularized stress tensor are zero,and no trace anomaly exists in general RW spacetimes.This is a new result that exceeds those found in de Sitter space.For the minimal coupling,the regularized spectra are also zero in the radiationdominant and matter-dominant stages,as well as in de Sitter space.The vanishing of these adiabatically regularized spectra is further confirmed by direct regularization of the Green's function.For a general coupling and general RW spacetimes,the regularized spectra can be negative under the conventional prescription.At a higher order of regularization,the spectra will generally become positive,but will also acquire IR divergence,which is inevitable for a massless field.To avoid the IR divergence,the inside-horizon regularization is applied.Through these procedures,nonnegative UV-and IR-convergent power spectrum and spectral energy density will eventually be achieved.
作者
张杨
王博
叶翾
Yang Zhang;Bo Wang;Xuan Ye(Department of Astronomy,CAS Key Laboratory for Researches in Galaxies and Cosmology,School of Astronomy and Space Sciences,University of Science and Technology of China,Hefei 230026,China)
基金
Supported by NSFC(11421303,11675165,11633001,11961131007)
B.Wang is supported by CPSF(2019M662168)。