64 research outputs found
Orthogonal polynomial expansions for the matrix exponential
AbstractMany different algorithms have been suggested for computing the matrix exponential. In this paper, we put forward the idea of expanding in either Chebyshev, Legendre or Laguerre orthogonal polynomials. In order for these expansions to converge quickly, we cluster the eigenvalues into diagonal blocks and accelerate using shifting and scaling
4D Higher Spin Black Holes with Nonlinear Scalar Fluctuations
We construct an infinite-dimensional space of solutions to Vasiliev's
equations in four dimensions that are asymptotic to AdS spacetime and superpose
massless scalar particle modes over static higher spin black holes. Each
solution is obtained by a large gauge transformation of an all-order
perturbatively defined particular solution given in a simple gauge, in which
the spacetime connection vanishes, the twistor space connection is holomorphic,
and all local degrees of freedom are encoded into the residual twistor space
dependence of the spacetime zero-forms. The latter are expanded over two dual
spaces of Fock space operators, corresponding to scalar particle and static
black hole modes, equipped with positive definite sesquilinear and bilinear
forms, respectively. Switching on an AdS vacuum gauge function, the twistor
space connection becomes analytic at generic spacetime points, which makes it
possible to reach Vasiliev's gauge, in which Fronsdal fields arise
asymptotically, by another large transformation given here at first order. The
particle and black hole modes are related by a twistor space Fourier transform,
resulting in a black hole backreaction already at the second order of classical
perturbation theory. We speculate on the existence of a fine-tuned branch of
moduli space that is free from black hole modes and directly related to the
quasi-local deformed Fronsdal theory. Finally, we comment on a possible
interpretation of the higher spin black hole solutions as black-hole
microstates.Comment: 63 pages + appendices; v2: reference added; v3: comments and
references added, typos correcte
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