论文标题
重新访问$ u（1）_ {b-l} $模型中的无菌中微子暗物质
Revisiting sterile neutrino dark matter in gauged $U(1)_{B-L}$ model
论文作者
论文摘要
我们重新检查了$ u（1）_ {b-l} $模型中的无菌中微子暗物质。通过追踪和仔细评估无菌中微子$ n $和额外的中性仪表玻色子$ z'$的数量密度的演变，进行了改进。结果，对于冻结的无菌中微子而言，$ u（1）_ {b-l} $的宇宙学量规耦合的事实比文献中报道的值小。这避免了$ z'$的过量生产，因此它与大爆炸核合成和宇宙微波背景限制对有效数量的中微子物种一致。同样，自由流长度约束排除了先前研究中得出的大参数空间。除了从标准型号Fermion Pairs中获得的$ N $的已知冻结对生产外，我们发现$ n $是由$ b-l $破坏标量质量的温度中的一对$ z'$主要产生的。因此，文献中$ u（1）_ {b-l} $标量贡献的幼稚截断是无效的。
We reexamine sterile neutrino dark matter in gauged $U(1)_{B-L}$ model. Improvements have been made by tracing and careful evaluation of the evolution of the number densities of sterile neutrinos $N$ and extra neutral gauge bosons $Z'$. As a result, the cosmologically-interesting gauge coupling of $U(1)_{B-L}$ for freeze-in sterile neutrinos turns out to be smaller than the values reported in the literature. This avoids the overproduction of $Z'$ so that it is consistent with the big bang nucleosynthesis and the cosmic microwave background constraints on the effective number of neutrino species. Similarly, the free-streaming length constraints exclude a large parameter space derived in previous studies. In addition to known freeze-in pair production of $N$ from the standard model fermion pairs, we find the case that $N$ is dominantly produced from a pair of $Z'$ at the temperature characterized by the $B-L$ breaking scalar mass. Thus, the naive truncation of the $U(1)_{B-L}$ scalar contribution made in the literature is not valid.
