### Abstract

We discuss black holes in an effective theory derived from a superstring model, which includes a dilaton field, a gauge field, and the Gauss-Bonnet term. Assuming U(1) or SU(2) symmetry for the gauge field, we find four types of spherically symmetric solutions, i.e., a neutral, an electrically charged, a magnetically charged, and a "colored" black hole, and discuss their thermodynamical properties and fate via the Hawking evaporation process. For neutral and electrically charged black holes, we find a critical point and a singular end point. Below the mass corresponding to the critical point, no solution exists, while the curvature on the horizon diverges and a naked singularity appears at the singular point. A cusp structure in the mass-entropy diagram is found at the critical point and black holes on the branch between the critical and singular points become unstable. For magnetically charged and "colored" black holes, the solution becomes singular just at the end point with a finite mass. Because the black hole temperature is always finite even at the critical point or the singular point, we may conclude that the evaporation process will not be stopped even at the critical point or the singular point, and the black hole will move to a dynamical evaporation phase or a naked singularity will appear.

Original language | English |
---|---|

Pages (from-to) | 739-753 |

Number of pages | 15 |

Journal | Physical Review D - Particles, Fields, Gravitation and Cosmology |

Volume | 55 |

Issue number | 2 |

Publication status | Published - 1997 Jan 15 |

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### ASJC Scopus subject areas

- Mathematical Physics
- Physics and Astronomy(all)
- Nuclear and High Energy Physics
- Physics and Astronomy (miscellaneous)

### Cite this

*Physical Review D - Particles, Fields, Gravitation and Cosmology*,

*55*(2), 739-753.

**Dilatonic black holes with a Gauss-Bonnet term.** / Torii, Takashi; Yajima, Hiroki; Maeda, Keiichi.

Research output: Contribution to journal › Article

*Physical Review D - Particles, Fields, Gravitation and Cosmology*, vol. 55, no. 2, pp. 739-753.

}

TY - JOUR

T1 - Dilatonic black holes with a Gauss-Bonnet term

AU - Torii, Takashi

AU - Yajima, Hiroki

AU - Maeda, Keiichi

PY - 1997/1/15

Y1 - 1997/1/15

N2 - We discuss black holes in an effective theory derived from a superstring model, which includes a dilaton field, a gauge field, and the Gauss-Bonnet term. Assuming U(1) or SU(2) symmetry for the gauge field, we find four types of spherically symmetric solutions, i.e., a neutral, an electrically charged, a magnetically charged, and a "colored" black hole, and discuss their thermodynamical properties and fate via the Hawking evaporation process. For neutral and electrically charged black holes, we find a critical point and a singular end point. Below the mass corresponding to the critical point, no solution exists, while the curvature on the horizon diverges and a naked singularity appears at the singular point. A cusp structure in the mass-entropy diagram is found at the critical point and black holes on the branch between the critical and singular points become unstable. For magnetically charged and "colored" black holes, the solution becomes singular just at the end point with a finite mass. Because the black hole temperature is always finite even at the critical point or the singular point, we may conclude that the evaporation process will not be stopped even at the critical point or the singular point, and the black hole will move to a dynamical evaporation phase or a naked singularity will appear.

AB - We discuss black holes in an effective theory derived from a superstring model, which includes a dilaton field, a gauge field, and the Gauss-Bonnet term. Assuming U(1) or SU(2) symmetry for the gauge field, we find four types of spherically symmetric solutions, i.e., a neutral, an electrically charged, a magnetically charged, and a "colored" black hole, and discuss their thermodynamical properties and fate via the Hawking evaporation process. For neutral and electrically charged black holes, we find a critical point and a singular end point. Below the mass corresponding to the critical point, no solution exists, while the curvature on the horizon diverges and a naked singularity appears at the singular point. A cusp structure in the mass-entropy diagram is found at the critical point and black holes on the branch between the critical and singular points become unstable. For magnetically charged and "colored" black holes, the solution becomes singular just at the end point with a finite mass. Because the black hole temperature is always finite even at the critical point or the singular point, we may conclude that the evaporation process will not be stopped even at the critical point or the singular point, and the black hole will move to a dynamical evaporation phase or a naked singularity will appear.

UR - http://www.scopus.com/inward/record.url?scp=0000852959&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0000852959&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0000852959

VL - 55

SP - 739

EP - 753

JO - Physical review D: Particles and fields

JF - Physical review D: Particles and fields

SN - 0556-2821

IS - 2

ER -