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arXiv 2403.01591hep-phastro-ph.COgr-qchep-th
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带维度六算子的标准模型单态扩展中的电弱相变

Electroweak Phase Transition in Singlet Extensions of The Standard Model with Dimension-Six Operators

V. K. Oikonomou, Apostolos Giovanakis

AI总结:

本文研究带维度六算子的标准模型单态扩展,发现其可实现强电弱相变,并扩展了先前被排除的参数空间,尤其适用于低单态质量情形。

摘要:

电弱相变的重要性不可否认,尽管最初人们认为它是二阶相变,但现在认为它是一阶相变。然而,在标准模型背景下,它并非强一阶相变,解决这一问题的办法是利用希格斯门户将希格斯粒子直接耦合到隐藏标量扇区。这可以实现强电弱相变,而隐藏标量间的耦合受到若干唯象约束的限制,如斯法勒伦速率准则和希格斯粒子不可见衰变道的分支比。在本工作中,我们考虑标准模型的标准单态扩展,包括将实单态标量场与希格斯二重态耦合的维度六非重整化算子。由此,我们研究了这些希格斯-单态耦合对电弱相变的影响。非重整化耦合所源自的有效理论被认为在超过15 TeV的能量下有效。我们表明,宇宙经历两步电弱相变:首先在高温下于单态扇区发生初级相变,随后从单态真空到电弱真空发生后续的一阶相变。单态的相变可以是二阶或一阶,取决于单态质量及其与希格斯粒子的耦合。特别地,我们表明维度六算子有助于在先前标准模型单态扩展中被排除的参数空间区域中产生强电弱相变。这一点对于低单态质量 \(m_S < m_H/2\) 尤为明显,由于希格斯玻色子的不可见分支比,文献中很少考虑这种情况。

英文摘要:

The significance of the electroweak phase transition is undeniable, and although initially it was believed that it was second-order, it is now believed that it is a first-order transition. However, it is not a strong first-order phase transition in the context of the Standard Model and the remedy to this issue is to use the Higgs portal and directly couple the Higgs to a hidden scalar sector. This can result in a strong electroweak phase transition, while the couplings to a hidden scalar are constrained by several phenomenological constraints, such as the sphaleron rate criterion and the branching ratio of the Higgs to invisible channels. In this work, we consider the standard singlet extensions of the Standard Model, including dimension-six non-renormalizable operators that couple a real singlet scalar field with the Higgs doublet. As a result, we examine the effects of those Higgs-singlet couplings on the electroweak phase transition. The effective theory, where the non-renormalizable couplings originate from, is considered to be active beyond 15$\,$TeV. As we show, the Universe experiences a two-step electroweak phase transition, a primary phase transition in the singlet sector at a high temperature, and then a subsequent first-order phase transition from the singlet vacuum to the electroweak vacuum. The singlet's phase transition can either be second-order or first-order, depending on the singlet mass and its couplings to the Higgs. In particular, we show that the dimension-six operator assists in generating a strong electroweak phase transition in regions of the parameter space that were excluded in the previous singlet extensions of the Standard Model. This is further apparent for low singlet masses \(m_S < m_H/2\) which are rarely taken into account in the literature due to the invisible branching ratio of the Higgs boson.

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