TOD

Abstract

It is well-known that the quantized charges x of 4D black holes may be assigned to elements of an integral Freudenthal triple system (FTS). The FTS is equipped with a quartic form q(x) whose square root yields the lowest order black hole entropy. We show that a subset of these black holes, for which q(x) is necessarily a perfect square, admit a ``Freudenthal dual'' with integer charges ~x, for which ~~x=-x and q(~x)=q(x).

[1] ''Black holes admitting a Freudenthal dual'', L. Borsten, D. Dahanayake, M.J. Duff, W. Rubens, Phys.Rev. D80 (2009) 026003 e-Print: arXiv:0903.5517 [hep-th]

[2] '' Freudenthal dual invariant Lagrangians'', L. Borsten, M.J. Duff, S. Ferrara ana A, Marrani (to appear).