We consider the Standard Model with three right-handed neutrinos to generate tiny neutrino masses by the seesaw mechanism. Especially, we investigate the case when one right-handed neutrino has the suppressed Yukawa coupling constants. Such a particle has a long lifetime and can produce an additional entropy by the decay. It is then discussed the impact of the entropy production on the gravitational wave background originated in the primordial inflation. We show that the mass and the coupling constants of the long-lived right-handed neutrino can be probed by the distortion of the gravitational wave spectrum, leading to the information of the mass of the lightest active neutrino. ar X iv :2 01 2. 13 52 7v 1 [ he pph ] 2 5 D ec 2 02 0

中文翻译：

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中微子质量和引力波背景

我们考虑具有三个右手中微子的标准模型，以通过跷跷板机制产生微小的中微子质量。特别是，我们研究了一个右手中微子具有抑制汤川耦合常数的情况。这种粒子的寿命很长，并且可以通过衰变产生额外的熵。然后讨论熵产生对起源于原始暴胀的引力波背景的影响。我们表明，长寿命右手中微子的质量和耦合常数可以通过引力波谱的畸变来探测，从而获得最轻的活性中微子的质量信息。ar X iv :2 01 2. 13 52 7v 1 [ he pph ] 2 5 D ec 2 02 0