宇宙中微子背景輻射

估計宇宙中微子背景輻射的溫度

$\sigma\propto gT^3$,

$\left(\frac{g_0}{g_1}\right)^{1/3}=\frac{T_1}{T_0}$,

T0T1分別代表電子-正電子湮滅前、後的溫度。電子-正電子湮滅后的宇宙溫度，即宇宙微波背景輻射的溫度。g0由粒子本身決定:[3]

• 光子：g0=2，因爲它們是玻色子
• 電子：g0=2；正電子：g0=7/8。它們都是費米子

$\frac{T_\nu}{T_\gamma} = \left(\frac{4}{11}\right)^{1/3}$

宇宙中微子背景輻射存在的間接證據

標准模型的預測和實際觀測

He
2
D

−0.65
（置信區間=68%）。[6] 這個結果同標準模型得到的理論值相當接近。

宇宙微波背景輻射與中微子背景輻射的相互作用

−0.86
（置信區間=68%）。[7]更靈敏的普朗克探測器有可能會在此基礎上將誤差降低一個量級。[8]

参考资料

1. ^ Lazauskas, R. ; Vogel, P.; Volpe, C. Charged current cross section for massive cosmological neutrinos impinging on radioactive nuclei. Journal of Physics G. 2008, 35: 025001 arXiv:0710.5312., page 3, 1st paragraph
2. ^ Vogel, Petr. How difficult it would be to detect Cosmic Neutrino Background?. lbl.gov. [2013-03-15].
3. ^ Steven Weinberg. Cosmology. Oxford University Press. 2008: 151. ISBN 978-0-19-852682-7.
4. ^ Fixsen, Dale; Mather, John. The Spectral Results of the Far-Infrared Absolute Spectrophotometer Instrument on COBE. Astrophysical Journal. 2002, 581 (2): 817–822. Bibcode:2002ApJ...581..817F. doi:10.1086/344402.
5. ^ Mangano, Gianpiero; et al. Relic neutrino decoupling including flavor oscillations. Nucl.Phys.B. 2005, 729 (1–2): 221–234. arXiv:hep-ph/0506164. Bibcode:2005NuPhB.729..221M. doi:10.1016/j.nuclphysb.2005.09.041.
6. ^ Cyburt, Richard; et al. New BBN limits on physics beyond the standard model from He-4. Astropart.Phys. 2005, 23 (3): 313–323. arXiv:astro-ph/0408033. Bibcode:2005APh....23..313C. doi:10.1016/j.astropartphys.2005.01.005.
7. ^ Komatsu, Eiichiro; et al. Seven-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation. The Astrophysical Journal Supplement Series. 2010, 192 (2): 18. arXiv:1001.4538. Bibcode:2011ApJS..192...18K. doi:10.1088/0067-0049/192/2/18.
8. ^ Bashinsky, Sergej; Seljak, Uroš. Neutrino perturbations in CMB anisotropy and matter clustering. Phys.Rev.D. 2004, 69 (8): 083002. arXiv:astro-ph/0310198. Bibcode:2004PhRvD..69h3002B. doi:10.1103/PhysRevD.69.083002.