In this paper, we investigate the motion of a classical spinning test particle in a background of a spherically symmetric black hole based on the novel four-dimensional Einstein–Gauss–Bonnet gravity [D. Glavan and C. Lin, Phys. Rev. Lett. 124, 081301 (2020)]. We find that the effective potential of a spinning test particle in this background could have two minima when the Gauss–Bonnet coupling parameter $\alpha$ is nearly in a special range $-8<\alpha /M^2<-2$ (M is the mass of the black hole), which means a particle can be in two separate orbits with the same spin-angular momentum and orbital angular momentum, and the accretion disc could have discrete structures. We also investigate the innermost stable circular orbits of the spinning test particle and find that the corresponding radius could be smaller than the cases in general relativity.

中文翻译：

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四维爱因斯坦-高斯-帽子黑洞中的自旋测试粒子

在本文中，我们基于新型的四维爱因斯坦-高斯-贝内特引力，研究了在球形对称黑洞背景下经典旋转测试粒子的运动[D。Glavan和C. Lin，物理学。莱特牧师 124，081301（2020）]。我们发现，当高斯-贝纳特耦合参数为高时，在这种背景下旋转测试粒子的有效电势可能有两个最小值。$\alpha$ 几乎在一个特殊范围内 $-8<\alpha /{\mathrm{中号}}^2<-2$（M是黑洞的质量），这意味着粒子可以处于两个具有相同的自旋角动量和轨道角动量的独立轨道中，并且吸积盘可能具有离散的结构。我们还研究了自旋测试粒子的最内层圆形轨道，发现相应的半径可能小于广义相对论的情况。