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arXiv 1812.08613hep-thgr-qchep-ph
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Weyl二次引力到Einstein action和Higgs势的自发破缺

Spontaneous breaking of Weyl quadratic gravity to Einstein action and Higgs potential

D. M. Ghilencea

摘要:

我们认为(规范)外尔重力作用,二次的标量曲率($\tilde R$)和外尔张量($\tilde C_{μνρσ}$)的外尔共形几何。在没有物质场的情况下,这种作用具有自发破缺,其中外尔规范场$ω_μ$在“吃掉”$\tilde R^2$项中的介子后,在施图克尔伯格机制中变得有质量(质量$m_ω\sim$普朗克尺度)。结果,我们恢复了具有正宇宙学常数的爱因斯坦-希尔伯特作用量和大质量Weyl规范场$ω_μ$的Proca作用量。在$m_ω$以下,这个场是双曲的,外尔几何变成黎曼几何。爱因斯坦-希尔伯特作用量只是外尔二次引力的一个“低能”极限,从而避免了以前长期存在的批评。在物质标量场$ϕ_1$(类希格斯)的存在下,与外尔规范对称性允许的耦合,在其自发破缺后,人们还获得了在低尺度下具有自发电弱对称性破缺的希格斯势。这是由$ξ_1ϕ_1^2 \tilde R$与Weyl几何的非最小耦合引起的,希格斯质量为$\proptoξ_1/ξ_0$($ξ_0$是$\tilde R^2$项的系数)。在实际模型中,$ξ_1$必须经典地调整$ξ_1\ll ξ_0$。我们评论这个值的量子稳定性。

英文摘要:

We consider the (gauged) Weyl gravity action, quadratic in the scalar curvature ($\tilde R$) and in the Weyl tensor ($\tilde C_{μνρσ}$) of the Weyl conformal geometry. In the absence of matter fields, this action has spontaneous breaking in which the Weyl gauge field $ω_μ$ becomes massive (mass $m_ω\sim$ Planck scale) after "eating" the dilaton in the $\tilde R^2$ term, in a Stueckelberg mechanism. As a result, one recovers the Einstein-Hilbert action with a positive cosmological constant and the Proca action for the massive Weyl gauge field $ω_μ$. Below $m_ω$ this field decouples and Weyl geometry becomes Riemannian. The Einstein-Hilbert action is then just a "low-energy" limit of Weyl quadratic gravity which thus avoids its previous, long-held criticisms. In the presence of matter scalar field $ϕ_1$ (Higgs-like), with couplings allowed by Weyl gauge symmetry, after its spontaneous breaking one obtains in addition, at low scales, a Higgs potential with spontaneous electroweak symmetry breaking. This is induced by the non-minimal coupling $ξ_1ϕ_1^2 \tilde R$ to Weyl geometry, with Higgs mass $\proptoξ_1/ξ_0$ ($ξ_0$ is the coefficient of the $\tilde R^2$ term). In realistic models $ξ_1$ must be classically tuned $ξ_1\ll ξ_0$. We comment on the quantum stability of this value.

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