论文标题
Palatini配方中的轴心质量问题和非最小重力耦合
Axion Quality Problem and Non-Minimal Gravitational Coupling in the Palatini Formulation
论文作者
论文摘要
在Axion模型中，全局U（1）Peccei-Quinn（PQ）对称性被重力的非扰动作用（例如轴突虫洞）明确打破。由于虫洞引起的PQ对称性的引力违规足够大，足以使PQ机制无效，PQ机制被称为轴突质量问题。最近，提出了一种新的解决质量问题的解决方案，其中引入了轴支球场与重力$ξ$的非最小耦合，以抑制虫洞的贡献。在这项工作中，我们以不同但同样有效的重力表述（即Palatini公式）重新审视问题，其中RICCI标量仅由连接确定。我们首先在Palatini公式中找到轴子虫洞溶液，采用完整的动态径向模式以及轴向模式，然后证明质量问题仍然可以通过非最小耦合$ξ$解决。 palatini公式中的$ξ$的要求下限略高于公式公式中的要求。
In axion models, the global U(1) Peccei-Quinn (PQ) symmetry is explicitly broken by non-perturbative effects of gravity, such as axionic wormholes. The gravitational violation of the PQ symmetry due to wormholes is large enough to invalidate the PQ mechanism, which is entitled as the axion quality problem. Recently, a novel solution to this quality problem was suggested, where the non-minimal coupling of the axion field to gravity $ξ$ is introduced to suppress the wormhole contribution. In this work, we revisit the problem in a different but equally valid formulation of gravity, namely the Palatini formulation, where the Ricci scalar is solely determined by connection. We first find the axionic wormhole solution in the Palatini formulation, taking the full dynamical radial mode as well as the axial mode, then show that the quality problem is still resolved with the non-minimal coupling $ξ$. The requested lower bound of $ξ$ in the Palatini formulation turns out to be slightly higher than that in the metric formulation.
