On the thermodynamics of the black holes of the Cano-Ruipérez 4-dimensional string effective action

Nov 15, 2024
23 pages
e-Print:
Report number:
  • IFT-UAM/CSIC-24-160,
  • MPP-2024-221

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Abstract: (arXiv)
The Cano-Ruipérez 4-dimensional string effective action is the simplest consistent truncation of the first-order in α\alpha' heterotic string effective action compactified on T6^{6}. This theory contains, on top of the metric, a dilaton and an axion that couple to the Gauss-Bonnet term and to the Pontrjagin density which suggests a very strong relation between the physical and geometrical properties of its solutions. In this paper we study the thermodynamics of the string black-hole solutions of this theory using Wald's formalism. We construct the on-shell closed generalized Komar, dilaton and axion 2-form charges, and we used them to find the Smarr formula (that we test on the Schwarzschild and Kerr solutions) and to prove no-(primary)-hair theorems for the scalar. We find that α\alpha' plays the role of a thermodynamical variable with an associated chemical potential. We also notice the occurrence of non-standard gravitational charges in the Wald entropy and scalar charges.
Note:
  • 23 pages + appendices