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Symmetries of complex analytic vector fields with an essential singularity on the Riemann sphere

  • Alvaro Alvarez-Parrilla EMAIL logo and Jesús Muciño-Raymundo
Published/Copyright: October 5, 2021
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Abstract

We consider the family (s, r, d) of all singular complex analytic vector fields X(z)=Q(z)P(z)eE(z)zon the Riemann sphere where Q, P, are polynomials with deg Q = s, deg P = r and deg = d ≥ 1. Using the pullback action of the affine group Aut(ℂ) and the divisors for X, we calculate the isotropy groups Aut(ℂ)X of discrete symmetries for X (s, r, d). The subfamily (s, r, d)id of those X with trivial isotropy group in Aut(ℂ) is endowed with a holomorphic trivial principal Aut(ℂ)-bundle structure. A necessary and sufficient arithmetic condition on s, r, d ensuring the equality (s, r, d) = (s, r, d)id is presented. Moreover, those X (s, r, d) \ (s, r, d)id with non-trivial isotropy are realized. This yields explicit global normal forms for all X (s, r, d). A natural dictionary between analytic tensors, vector fields, 1-forms, orientable quadratic differentials and functions on Riemann surfaces M is extended as follows. In the presence of nontrivial discrete symmetries Γ < Aut(M), the dictionary describes the correspondence between Γ-invariant tensors on M and tensors on M /Γ.

MSC 2010: 34M35; 32S65; 30D20; 58D19
  1. Communicated by: P. Eberlein

Acknowledgements

The authors wish to thank Adolfo Guillot for useful comments, as well as the anonymous referee for the generous criticism that improved the present work.

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Received: 2019-02-27
Revised: 2020-04-07
Published Online: 2021-10-05
Published in Print: 2021-10-26

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