### Abstract

We consider a superradiance effect around rotating dilatonic black holes. We analyze two cases: one is an exact solution with the coupling constant α = 3, which effective action is reduced from the 5-dimensional Kaluza-Klein theory, and the other is a slowly rotating dilatonic black holes with arbitrary coupling constant. We find that there exists a critical value (α ∼ 1), which is predicted from a superstring model, and the superradiant emission rate with coupling larger than the critical value becomes much higher than the Kerr-Newman case (α = 0) in the maximally charged limit. Consequently, 4-dimensional primordial black holes in higher dimensional unified theories are either rotating but almost neutral or charged but effectively non-rotating.

Original language | English |
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Pages (from-to) | 29-34 |

Number of pages | 6 |

Journal | Physics Letters B |

Volume | 340 |

Issue number | 1-2 |

DOIs | |

Publication status | Published - 1994 Dec 1 |

### ASJC Scopus subject areas

- Nuclear and High Energy Physics

## Cite this

*Physics Letters B*,

*340*(1-2), 29-34. https://doi.org/10.1016/0370-2693(94)91293-9