Index theory and dynamical symmetry enhancement near IIB horizons

Journal article, 2013

We show that the number of supersymmetries of JIB black hole horizons is N = 2N_ + 2 index(D-lambda), where index(D-lambda) is the index of the Dirac operator twisted with the line bundle lambda(1/2) of IIB scalars, and N_ is the dimension of the kernel of a horizon Dirac operator which depends on IIB fluxes. Therefore, all IIB horizons preserve an even number of supersymmetries. In addition if the horizons have non-trivial fluxes and N_ not equal 0, then index(D-lambda) >= 0 and the horizons admit an sl(2,R) symmetry subalgebra. This provides evidence that all such horizons have an AdS/CFT dual. Furthermore if the orbits of sl(2,R) are two-dimensional, the IIB horizons are warped products AdS(2) x(w) S.