纳赫兹引力波对单态暗物质模型中电弱相变的影响

Implications of nano-Hertz gravitational waves on electroweak phase transition in the singlet dark matter model

受脉冲星定时阵列合作组最近观测到的纳赫兹级随机引力波证据的启发,本文在标准模型的单态扩展中探讨了利用极端过冷的电弱相变解释这些观测结果的可能性,并考虑了相变对于暗物质的影响.研究结果表明,通过精细调节模型参数,相应的渗透温度可以连续降低到1 GeV甚至更低.在如此低的渗透温度下,单态暗物质可能在电弱相变之前就脱离热平衡,从而从热辐射中冻结出来.因此,相变期间产生的熵可以显著影响暗物质的残留密度.这减轻了单态扩展模型中同时解释重子生成和满足暗物质直接探测限制的压力,暗示着所考虑的新物理模型可能存在更广阔的参数空间,并可在未来的实验中得到验证.

Inspired by the recent evidences of nano-Hertz stochastic gravitational waves observed by the pulsar timing array collaborations,we explore their implied supercooled electroweak phase transition in the singlet extension of the standard model.Our findings reveal that by adjusting the model parameter at per milli level,the corresponding percolation temperature can be continuously lowered to 1 GeV.With such a low percolation temperature,the singlet dark matter may freeze out before the electroweak phase transition,and,consequently,the entropy generated during the transition can significantly affect the dark matter relic density.It alleviates the tension between the requirement of a strong electroweak phase transition and the constraints imposed by dark matter direct detection,and can be tested in future experiments.