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arXiv 1111.7264hep-phastro-ph.COgr-qc
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WMAP和LHC7之后的中微子宇宙学

Neutrino Cosmology after WMAP and LHC7

Luis Alfredo Anchordoqui, Haim Goldberg

摘要:

规范扩展的U(1)_C \times SU(2)_L \times U(1)_{I_R} \times U(1)_L模型具有将标准模型的两个主要整体对称性(重子数B和轻子数L)提升到局域规范对称性的吸引人的性质。U(1)_L对称性阻止了Majorana质量的产生,导致了三个超弱相互作用的右手中微子。这也使得B-L对称性是非反常的。我们证明了这些狄拉克态的超弱相互作用(通过它们与TeV尺度的B-L规范玻色子的耦合)允许右手中微子在QCD相变之上的退耦:175 MeV < T_{ν_R} ^{dec} < 250 MeV。在这个过渡区中,在BBN和CMB时刻,ν_L和ν_R之间的剩余温度比产生额外的相对论自由度。在3 TeV < M_{B-L} < 6 TeV的情况下,与WMAP的7年数据和最新的原始^4 He质量分数估计值一致(在1σ以内)。该模型是完全预测的,并且可以面对LHC 7和LHC 14的双射流和双轻子数据(或缺乏数据)。

英文摘要:

The gauge-extended U(1)_C \times SU(2)_L \times U(1)_{I_R} \times U(1)_L model has the attractive property of elevating the two major global symmetries of the standard model (baryon number B and lepton number L) to local gauge symmetries. The U(1)_L symmetry prevents the generation of Majorana masses, leading to three superweakly interacting right-handed neutrinos. This also renders a B-L symmetry non-anomalous. We show that the superweak interactions of these Dirac states (through their coupling to the TeV-scale B-L gauge boson) permit right-handed neutrino decoupling just above the QCD phase transition: 175 MeV < T_{ν_R}^{dec} < 250 MeV. In this transitional region, the residual temperature ratio between ν_L and ν_R generates extra relativistic degrees of freedom at BBN and at the CMB epochs. Consistency (within 1σ) with both WMAP 7-year data and the most recent estimate of the primordial ^4He mass fraction is achieved for 3 TeV < M_{B-L} < 6 TeV. The model is fully predictive, and can be confronted with dijet and dilepton data (or lack thereof) from LHC7 and, eventually, LHC14.

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