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Filipe Moura, Universidade do Minho

Spherically symmetric Gauss-Bonnet black holes in d dimensions: perturbations and absorption cross section

We compute the tensorial perturbations to a general spherically symmetric metric in d dimensions with string-theoretical Gauss-Bonnet corrections. We use this result to derive their respective potential, which may be used to study the stability of such solutions. We then obtain a general formula for the absorption cross section of low-frequency tensor type gravitational waves for every black hole of this kind. After obtaining the general solution to the dilaton in this kind of background, we derive a new black hole solution with dilatonic charge in heterotic string theory, to which we apply our formula. We compare the results for the absorption cross section with the black hole entropy, obtained through Wald's formula.