论文标题
狄拉克中微子和$ n _ {\ rm eff} $ ii：冻结案例
Dirac neutrinos and $N_{\rm eff}$ II: the freeze-in case
论文作者
论文摘要
我们讨论了Dirac Neutminos的右手组成部分$ν_r$具有新的相互作用，可能会导致对有效数量的相对性中微子物种$ n _ {\ rm eff} $的可测量贡献。我们旨在针对各种可能性的独立模型和全面研究。 $ν_r$创世的过程涵盖了热物种的衰减或散射，具有旋转0，旋转1/2或Spin-1初始或最终状态的过程。我们通过数值和分析来计算$ν_r$对$ n _ {\ rm eff} $的贡献，主要是在冻结制度中，因为冻结式制度以前已经研究过。虽然我们的近似分析结果仅适用于冻结，但我们的数值计算也可用于冻结，包括两个制度之间的过渡。使用$ n _ {\ rm eff} $上的当前和将来的约束，我们获得了在新交互的群众和耦合上的CMB实验的限制和敏感性。作为副产品，我们获得了higgs-neutrino相互作用的贡献，$Δn_ {\ rm eff}^{\ rm sm} \大约7.5 \ times10^{ - 12} $，假设中性质量为0.1 eV，并由标准的HigGS机械化产生。
We discuss Dirac neutrinos whose right-handed component $ν_R$ has new interactions that may lead to a measurable contribution to the effective number of relativistic neutrino species $N_{\rm eff}$. We aim at a model-independent and comprehensive study on a variety of possibilities. Processes for $ν_R$-genesis from decay or scattering of thermal species, with spin-0, spin-1/2, or spin-1 initial or final states are all covered. We calculate numerically and analytically the contribution of $ν_R$ to $N_{\rm eff}$ primarily in the freeze-in regime, since the freeze-out regime has been studied before. While our approximate analytical results apply only to freeze-in, our numerical calculations work for freeze-out as well, including the transition between the two regimes. Using current and future constraints on $N_{\rm eff}$, we obtain limits and sensitivities of CMB experiments on masses and couplings of the new interactions. As a by-product, we obtain the contribution of Higgs-neutrino interactions, $ΔN_{\rm eff}^{\rm SM} \approx 7.5\times10^{-12}$, assuming the neutrino mass is 0.1 eV and generated by the standard Higgs mechanism.
