English

The summatory function of the M\"obius function in function fields

Number Theory 2011-11-16 v2

Abstract

We study the growth rate of the summatory function of the M\"obius function in the context of an algebraic curve over a finite field. Our work shows a strong resemblance to its number field counterpart, which was proved by Ng in 2004. We find an expression for a bound of the summatory function, which becomes sharp when the zeta zeros of the curve satisfy a certain linear independence property. Extending a result of Kowalski in 2008, we prove that most curves in the family of universal hyperelliptic curves satisfy this property. Then, we consider a certain geometric average of such bound in this family, using Katz and Sarnak's reformulation of the equidistribution theorem of Deligne. Lastly, we study an asymptotic behavior of this average as the family gets larger by evaluating the average values of powers of characteristic polynomials of random unitary symplectic matrices.

Keywords

Cite

@article{arxiv.1008.4711,
  title  = {The summatory function of the M\"obius function in function fields},
  author = {Byungchul Cha},
  journal= {arXiv preprint arXiv:1008.4711},
  year   = {2011}
}

Comments

16 pages. In this revision, an error in residue calculation in Section 2 is corrected, and a few bibliographic items are updated

R2 v1 2026-06-21T16:05:58.268Z