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Gauss-Bonnet corrected string/black hole transition in large dimensions

Bum-Hoon Lee, Hocheol Lee, Somyadip Thakur

Abstract

We develop a unified analytic treatment of the Horowitz--Polchinski string/black hole correspondence that systematically incorporates higher-derivative corrections to gravity. Working in Euclidean signature -- where the Euclidean black hole and the thermal scalar arise as competing saddles of the same finite-temperature ensemble -- we include the Gauss--Bonnet term. The analysis is rendered tractable in this UV--sensitive regime by the large-\(D\) expansion, which sharply separates the geometry into a universal near-zone and an asymptotic far-zone. In the near-zone, the coupled large-\(D\) equations reduce the thermal-scalar sector to an exactly solvable Schrödinger problem, from which we extract the \(α'\)-corrected decay exponent and the corresponding shift of the Hagedorn temperature. In the far-zone, we construct closed-form Euclidean solutions of Einstein--Gauss--Bonnet theory at leading order in both \(1/D\) and \(α'\). Matching the two regions yields the complete corrected saddle -- fixing its temperature, horizon data, and on--shell action -- and permits a fully analytic comparison of free energies between the thermal-scalar and black hole phases. This provides a controlled derivation of the HP correspondence point with explicit higher-curvature corrections.

Gauss-Bonnet corrected string/black hole transition in large dimensions

Abstract

We develop a unified analytic treatment of the Horowitz--Polchinski string/black hole correspondence that systematically incorporates higher-derivative corrections to gravity. Working in Euclidean signature -- where the Euclidean black hole and the thermal scalar arise as competing saddles of the same finite-temperature ensemble -- we include the Gauss--Bonnet term. The analysis is rendered tractable in this UV--sensitive regime by the large- expansion, which sharply separates the geometry into a universal near-zone and an asymptotic far-zone. In the near-zone, the coupled large- equations reduce the thermal-scalar sector to an exactly solvable Schrödinger problem, from which we extract the -corrected decay exponent and the corresponding shift of the Hagedorn temperature. In the far-zone, we construct closed-form Euclidean solutions of Einstein--Gauss--Bonnet theory at leading order in both and . Matching the two regions yields the complete corrected saddle -- fixing its temperature, horizon data, and on--shell action -- and permits a fully analytic comparison of free energies between the thermal-scalar and black hole phases. This provides a controlled derivation of the HP correspondence point with explicit higher-curvature corrections.
Paper Structure (96 sections, 354 equations, 4 figures, 3 tables)

This paper contains 96 sections, 354 equations, 4 figures, 3 tables.

Figures (4)

  • Figure 1: Quartic Landau coefficient $a_4(\lambda_{\rm GB})$ extracted from the NLO quartic contribution $\mathcal{F}^{(4)}$ to the dimensionally--reduced thermal-scalar free energy functional. The dependence on the Gauss--Bonnet coupling is U-shaped, with a pronounced minimum at finite $\lambda_{\rm GB}$ (marked by $\times$). In the vicinity of this minimum the leading nonlinearity in $\mathcal{F}[\chi_0]=\mathcal{F}_0+\mathcal{F}^{(2)}+\mathcal{F}^{(4)}+\cdots$ is parametrically suppressed, defining a quasi-tricritical window in which the system becomes especially sensitive to subleading corrections beyond the quartic Landau description.
  • Figure 2: Numerical solutions of second-order Eqs. \ref{['eq:EinsteinEq']}, \ref{['eq:DilatonEOM']} and \ref{['eq:ChiSchrodinger']}, where $\Lambda = 0$.
  • Figure 3: Numerical solutions of second-order Eqs. \ref{['eq:EinsteinEq']}, \ref{['eq:DilatonEOM']} and \ref{['eq:ChiSchrodinger']}, where $\ell = 20$.
  • Figure 4: Near-horizon solutions of reduced-order Eqs. \ref{['eq:reduced_eom_h']}, \ref{['eq:reduced_eom_g']}, \ref{['eq:reduced_eom_phi']} and \ref{['eq:reduced_eom_chi']}, where $\bar{\alpha} = 1$ and $\ell = 10^7$.