标题： 电弱真空衰变的引力修正：度规与Palatini方法 显示英文标题

标题： Gravitational corrections to electroweak vacuum decay: metric vs. Palatini

摘要： 我们考虑标准的爱因斯坦-希尔伯特-希格斯作用量，其中希格斯场通过项$\xi h^2 \mathcal{R}$与引力非最小耦合，并研究了在度规和Palatini两种重力表述下存在引力修正时电弱真空的稳定性。 为了从解析上识别这两种形式主义之间的差异，我们采用了一种微扰方法，在此方法中通过引力耦合常数的最低阶展开来考虑引力修正。 我们的分析表明，在Palatini形式主义中，众所周知的引力抑制真空衰变概率的效果，对于任意非最小耦合值$\xi$，相比于度规情况变得更为温和。 此外，我们发现，在Palatini形式主义中，引力修正的正性——这是理论单位性的必要条件——导致了一个下界$\xi>-1/12$。 显示英文摘要

摘要： We consider the standard Einstein-Hilbert-Higgs action where the Higgs field couples nonminimally with gravity via the term $\xi h^2 \mathcal{R}$, and investigate the stability of the electroweak vacuum in the presence of gravitational corrections in both the metric and Palatini formulations of gravity. In order to identify the differences between the two formalisms analytically, we follow a perturbative approach in which the gravitational corrections are taken into consideration via a leading order expansion in the gravitational coupling constant. Our analysis shows that in the Palatini formalism, the well-known effect of gravity suppressing the vacuum decay probability, becomes milder in comparison with the metric case for any value of the nonminimal coupling $\xi$. Furthermore, we have found that in the Palatini formalism, the positivity of the gravitational corrections, which is a necessary requirement for the unitarity of the theory, entails the lower bound $\xi>-1/12$.