Isotropic N-point basis functions and their properties

Oct 27, 2020
57 pages
Published in:
  • J.Phys.A 56 (2023) 32, 325204
  • Published: Jul 21, 2023
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Abstract: (IOP)
Isotropic functions of positions , i.e. functions invariant under simultaneous rotations of all the coordinates, are conveniently formed using spherical harmonics and Clebsch–Gordan coefficients. An orthonormal basis of such functions provides a formalism suitable for analyzing isotropic distributions such as those that arise in cosmology, for instance in the clustering of galaxies as revealed by large-scale structure surveys. The algebraic properties of the basis functions are conveniently expressed in terms of 6-j and 9-j symbols. The calculation of relations among the basis functions is facilitated by ‘Yutsis’ diagrams for the addition and recoupling of angular momenta.
Note:
  • 57 pages, submitted to Journal of Mathematical Physics, comments welcome
  • isotropic functions
  • expansion of isotropic functions
  • isotropy in cosmology