The superradiant instability of black hole space-times has been used to place limits on ultra-light bosonic particles. We show that these limits are model dependent. While the initial growth of the mode is gravitational and thus model independent, the ability to place a limit on new particles requires the mode to grow unhindered to a large number density. Non-linear interactions between the particle and other light degrees of freedom that are mediated through higher dimension operators can damp this growth, eliminating the limit. However, these non-linearities may also destroy a cosmic abundance of these light particles, an attractive avenue for their discovery in several experiments. We study the specific example of the QCD axion and show that it is easy to construct models where these non-linearities eliminate limits from superradiance while preserving their cosmic abundance.

中文翻译：

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消除超辐射限制的发条机制

黑洞时空的超辐射不稳定性已被用来限制超轻玻色子粒子。我们表明这些限制是依赖于模型的。虽然模式的初始增长是引力，因此与模型无关，但对新粒子施加限制的能力要求模式不受阻碍地增长到大数密度。通过高维算子介导的粒子和其他光自由度之间的非线性相互作用可以抑制这种增长，消除限制。然而，这些非线性也可能破坏这些光粒子的宇宙丰度，这是它们在几个实验中发现的一个有吸引力的途径。