#### Vol. 11, No. 9, 2017

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On the density of zeros of linear combinations of Euler products for $\sigma \gt {}$1

### Mattia Righetti

Vol. 11 (2017), No. 9, 2131–2163
##### Abstract

It has been conjectured by Bombieri and Ghosh that the real parts of the zeros of a linear combination of two or more $L$-functions should be dense in the interval $\left[1,{\sigma }^{\ast }\right]$, where ${\sigma }^{\ast }$ is the least upper bound of the real parts of such zeros. In this paper we show that this is not true in general. Moreover, we describe the optimal configuration of the zeros of linear combinations of orthogonal Euler products by showing that the real parts of such zeros are dense in subintervals of $\left[1,{\sigma }^{\ast }\right]$ whenever ${\sigma }^{\ast }>1$.

##### Keywords
zeros of Dirichlet series, value distribution, asymptotic distribution functions, convexity
Primary: 11M41
Secondary: 11M26
##### Milestones
Received: 21 November 2016
Revised: 18 July 2017
Accepted: 14 August 2017
Published: 2 December 2017
##### Authors
 Mattia Righetti Dipartimento di Matematica Università di Genova 16146, Genova Italy Centre de Recherches Mathématiques Université de Montréal P.O. Box 6128 Centre-Ville Station Montréal QC H3C 3J7 Canada