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arXiv 1709.10322hep-phastro-ph.COhep-th
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具有隐标度不变性的标准模型中的低温电弱相变

Low temperature electroweak phase transition in the Standard Model with hidden scale invariance

Suntharan Arunasalam, Archil Kobakhidze, Cyril Lagger, Shelley Liang, Albert Zhou

摘要:

我们讨论了宇宙学相变内的标准模型,其中包括自发破缺标度不变性作为一个低能量的理论。除了标准模型场之外,极小模型还包括一个光量子,它通过维度嬗变的机制获得一个大的真空期望值(VEV)。在真空能量抵消的假设下,电子子在2圈量级上发展出非常小的质量。结果表明,在零温度下经典的Higgs势中存在一个平坦的方向,而量子势中存在两个(几乎)简并的局部极小值,它们具有未破缺和破缺的电弱对称性。我们发现,在这个模型中的宇宙学电弱相变只能触发在低温下,$T\lesssim 132$ MeV的QCD手征对称性破缺相变。此外,与标准情况不同的是,宇宙通过一阶相变进入手征对称性破缺真空,这产生了峰值频率为$\sim 10^{-8}$ Hz的随机引力背景,并触发了大约太阳质量的原始黑洞的产生。对宇宙学相变的这些特征的观测,再加上对一个光量子的探测,将为尺度不变性在粒子物理学中的基本作用提供一个强有力的暗示。

英文摘要:

We discuss a cosmological phase transition within the Standard Model which incorporates spontaneously broken scale invariance as a low-energy theory. In addition to the Standard Model fields, the minimal model involves a light dilaton, which acquires a large vacuum expectation value (VEV) through the mechanism of dimensional transmutation. Under the assumption of the cancellation of the vacuum energy, the dilaton develops a very small mass at 2-loop order. As a result, a flat direction is present in the classical dilaton-Higgs potential at zero temperature while the quantum potential admits two (almost) degenerate local minima with unbroken and broken eletroweak symmetry. We found that the cosmological electroweak phase transition in this model can only be triggered by a QCD chiral symmetry breaking phase transition at low temperatures, $T\lesssim 132$ MeV. Furthermore, unlike the standard case, the universe settles into the chiral symmetry breaking vacuum via a first-order phase transition which gives rise to a stochastic gravitational background with a peak frequency $\sim 10^{-8}$ Hz as well as triggers the production of approximately solar mass primordial black holes. The observation of these signatures of cosmological phase transitions together with the detection of a light dilaton would provide a strong hint of the fundamental role of scale invariance in particle physics.

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