English

Bohr's absolute convergence problem for $\mathcal{H}_p$-Dirichlet series in Banach spaces

Functional Analysis 2019-05-31 v1

Abstract

The Bohr-Bohnenblust-Hille Theorem states that the width of the strip in the complex plane on which an ordinary Dirichlet series nanns\sum_n a_n n^{-s} converges uniformly but not absolutely is less than or equal to 1/2, and this estimate is optimal. Equivalently, the supremum of the absolute convergence abscissas of all Dirichlet series in the Hardy space H\mathcal{H}_\infty equals 1/2. By a surprising fact of Bayart the same result holds true if H\mathcal{H}_\infty is replaced by any Hardy space Hp\mathcal{H}_p, 1p<1 \le p < \infty, of Dirichlet series. For Dirichlet series with coefficients in a Banach space XX the maximal width of Bohr's strips depend on the geometry of XX; Defant, Garc\'ia, Maestre and P\'erez-Garc\'ia proved that such maximal width equal 11/\ct(X)1- 1/\ct(X), where \ct(X)\ct(X) denotes the maximal cotype of XX. Equivalently, the supremum over the absolute convergence abscissas of all Dirichlet series in the vector-valued Hardy space H(X)\mathcal{H}_\infty(X) equals 11/\ct(X)1- 1/\ct(X). In this article we show that this result remains true if H(X)\mathcal{H}_\infty(X) is replaced by the larger class Hp(X)\mathcal{H}_p(X), 1p<1 \le p < \infty.

Keywords

Cite

@article{arxiv.1304.5377,
  title  = {Bohr's absolute convergence problem for $\mathcal{H}_p$-Dirichlet series in Banach spaces},
  author = {Daniel Carando and Andreas Defant and Pablo Sevilla-Peris},
  journal= {arXiv preprint arXiv:1304.5377},
  year   = {2019}
}