Recently BICEP2 collaboration has announced the detection of the primordial gravitational waves at high confidence level. In light of the results of B-modes power spectrum from BICEP2 and using the based ACDM, a const...Recently BICEP2 collaboration has announced the detection of the primordial gravitational waves at high confidence level. In light of the results of B-modes power spectrum from BICEP2 and using the based ACDM, a constraint on the tensor-to-scalar ratio r = 0.20-0.05＋0.07 （68% C.L.） can be obtained, however, this result is in apparent tension with the limit on standard inflation models from the recent PLANCK measurement, r 〈 0.11 （95% C.L.）. Herein we review the recent progress on the cosmological studies after BICEP2 and discuss on different ways of reconciling the tension between PLANCK and BICEP2 data. We will discuss possible modifications on the standard cosmological model, such as including the running of scalar spectral index or other cosmological parameters correlated with inflationary cosmological parameters, or tilting the primordial power spectrum at large scales by introducing a cut off which can be predicted by bouncing cosmology. We will also comment on another possibility of generating extra B-modes of CMB polarization, namely by a non-zero polarization rotation angle during its transferring from the last scattering surface.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 11033005, 11322325, 11075074, 11121092, 11033005 and 11375202)the National Basic Research Program of China (Grant No. 2010CB83300)+1 种基金the Program for New Century Excellent Talents in Universitythe National Youth Thousand Talents Program and the Strategic Priority Research Program "The Emergence of Cosmological Structures" of the Chinese Academy of Sciences (Grant No. XDB09000000)
文摘Recently BICEP2 collaboration has announced the detection of the primordial gravitational waves at high confidence level. In light of the results of B-modes power spectrum from BICEP2 and using the based ACDM, a constraint on the tensor-to-scalar ratio r = 0.20-0.05＋0.07 （68% C.L.） can be obtained, however, this result is in apparent tension with the limit on standard inflation models from the recent PLANCK measurement, r 〈 0.11 （95% C.L.）. Herein we review the recent progress on the cosmological studies after BICEP2 and discuss on different ways of reconciling the tension between PLANCK and BICEP2 data. We will discuss possible modifications on the standard cosmological model, such as including the running of scalar spectral index or other cosmological parameters correlated with inflationary cosmological parameters, or tilting the primordial power spectrum at large scales by introducing a cut off which can be predicted by bouncing cosmology. We will also comment on another possibility of generating extra B-modes of CMB polarization, namely by a non-zero polarization rotation angle during its transferring from the last scattering surface.
