2014/04/01 by Hong Li, Li, Hong, Jun-Qing Xia +3
Physics and Astronomy · #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph) #astro-ph.CO #hep-ex #hep-ph
paper · pdf · doi:10.48550/arxiv.1404.0238
7 pages, 2 tables and 6 figures
arxiv created 2014/05/07 · arxiv updated 2014/05/08
Recently, BICEP2 collaboration has released their results on the measurements of the CMB polarizations. In the framework of the ΛCDM with a power law form of the scalar primordial power spectrum, this new measurement on the B-mode puts a tight constraint on tensor/scalar ratio r=0.2+0.07-0.05~(1σ), which however is in tension with the Planck limit, r<0.11 (95% C.L.). In this paper, we consider various extensions of the ΛCDM model by introducing extra cosmological parameters such as the equation state of dark energy w, the curvature of the universe Ωk, the running of the scalar power spectrum index αs, the sum of the neutrino mass Σmν, the effective number of neutrinos Neff, the tensor power spectrum index nt, then perform the global fit to the BICEP2, Planck and also the SN and BAO data. Our results show the cosmological parameters αs and nt are highly and directly correlated with the tensor/scalar ratio r. However indirectly the parameters Ωk and Neff are also correlated with r. We will in this paper give the numerical values on the parameters introduced and show explicitly how the tension between the BICEP2 and Planck is effectively alleviated by the inclusion of the parameters Ωk, αs, Neff and nt separately.