Iso Satoshi, Serpico Pasquale D, Shimada Kengo
Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK) and Graduate University for Advanced Studies (SOKENDAI), Oho 1-1, Tsukuba, Ibaraki 305-0801, Japan.
LAPTh, Université de Savoie and CNRS, 74941 Annecy Cedex, France.
Phys Rev Lett. 2017 Oct 6;119(14):141301. doi: 10.1103/PhysRevLett.119.141301. Epub 2017 Oct 5.
If the electroweak sector of the standard model is described by classically conformal dynamics, the early Universe evolution can be substantially altered. It is already known that-contrarily to the standard model case-a first-order electroweak phase transition may occur. Here we show that, depending on the model parameters, a dramatically different scenario may happen: A first-order, six massless quark QCD phase transition occurs first, which then triggers the electroweak symmetry breaking. We derive the necessary conditions for this dynamics to occur, using the specific example of the classically conformal B-L model. In particular, relatively light weakly coupled particles are predicted, with implications for collider searches. This scenario is also potentially rich in cosmological consequences, such as renewed possibilities for electroweak baryogenesis, altered dark matter production, and gravitational wave production, as we briefly comment upon.
如果标准模型的电弱部分由经典共形动力学描述，那么早期宇宙的演化可能会被显著改变。已知与标准模型情况相反，可能会发生一阶电弱相变。在这里我们表明，根据模型参数，可能会出现截然不同的情况：首先发生一阶、六个无质量夸克的量子色动力学相变，然后引发电弱对称性破缺。我们以经典共形B-L模型的具体例子推导了这种动力学发生的必要条件。特别是，预测了相对较轻的弱耦合粒子，这对对撞机搜索有影响。正如我们简要评论的那样，这种情况在宇宙学后果方面也可能很丰富，例如电弱重子生成有了新的可能性、暗物质产生发生改变以及引力波产生。
