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arXiv 1211.2154astro-ph.COhep-ph
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用宇宙学数据检验标准和非标准中微子物理学

Testing standard and non-standard neutrino physics with cosmological data

Elena Giusarma, Roland de Putter, Olga Mena

摘要:

利用最新的宇宙学数据计算了标准和非标准情况下中微子质量和中微子种类有效数量的宇宙学约束。我们的宇宙学数据集包括重子振荡光谱巡天(BOSS)的数据发布9 CMASS样本中的重子声振荡(BAO)特征的测量。我们详细研究了参数之间的不同退化,以及分析中使用的不同数据集的影响。当考虑三个活跃中微子质量之和的界限时,来自星系团测量的BAO信号中的信息与来自物质功率谱的形状信息大致相同。我们发现最严格的界限是在95%CL下总和m_nu<0.32 eV。当非标准的中微子的情况下,neff无质量或大质量的中微子物种进行检查,功率谱形状测量提供稍好的界限比BAO信号只,由于参数简并的打破。最近的BOSS数据结合CMB和哈勃空间望远镜的测量,在无质量中微子情况下得到neff=3.66^{+0.20 +0.73}-0.21 -0.69},在有质量中微子情况下得到类似的结果。因此,当考虑到最新的宇宙学数据集时,文献中经常声称的额外辐射neff>3的证据仍然停留在2 σ水平。威尔金森微波各向异性探测器的测量结合哈勃空间望远镜的哈勃参数,在限制三个活跃中微子质量的总和或无质量中微子种类的数量方面非常强大。然而,如果允许前两个参数自由变化,那么这两个宇宙学探测器组合的边界会变差一个数量级。

英文摘要:

Cosmological constraints on the sum of neutrino masses and on the effective number of neutrino species in standard and non-standard scenarios are computed using the most recent available cosmological data. Our cosmological data sets include the measurement of the Baryonic Acoustic Oscillation (BAO) feature in the Data Release 9 CMASS sample of the Baryon Oscillation Spectroscopic Survey (BOSS). We study in detail the different degeneracies among the parameters, as well as the impact of the different data sets used in the analyses. When considering bounds on the sum of the three active neutrino masses, the information in the BAO signal from galaxy clustering measurements is approximately equally powerful as the shape information from the matter power spectrum. The most stringent bound we find is sum m_nu<0.32 eV at 95 % CL. When non-standard neutrino scenarios with neff massless or massive neutrino species are examined, power spectrum shape measurements provide slightly better bounds than the BAO signal only, due to the breaking of parameter degeneracies. Recent BOSS data combined with CMB and Hubble Space Telescope measurements give neff=3.66^{+0.20 +0.73}_{-0.21 -0.69} in the massless neutrino scenario, and similar results are obtained in the massive case. The evidence for extra radiation neff>3 often claimed in the literature therefore remains at the 2 sigma level when considering up-to-date cosmological data sets. Measurements from the Wilkinson Microwave Anisotropy Probe combined with a prior on the Hubble parameter from the Hubble Space Telescope are very powerful in constraining either the sum of the three active neutrino masses or the number of massless neutrino species. If the former two parameters are allowed to freely vary, however, the bounds from the combination of these two cosmological probes get worse by an order of magnitude.

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