Journal of Integer Sequences, Vol. 16 (2013), Article 13.2.13

Valuations of v-adic Power Sums and Zero Distribution for the Goss v-adic Zeta Function for Fq[t]

Dinesh S. Thakur
Department of Mathematics
University of Arizona
Tucson, AZ 85721


We study the valuation at an irreducible polynomial v of the v-adic power sum, for exponent k (or -k), of polynomials of a given degree d in Fq[t], as a sequence in d (or k). Understanding these sequences has immediate consequences, via standard Newton polygon calculations, for the zero distribution of the corresponding v-adic Goss zeta functions. We concentrate on v of degree one and two and give several results and conjectures describing these sequences. As an application, we show, for example, that the naive Riemann hypothesis statement which works in several cases, needs modifications, even for a prime of degree two. In the last section, we give an elementary proof of (and generalize) a product formula of Pink for the leading term of the Goss zeta function.

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Received August 1 2012; revised version received January 7 2013. Published in Journal of Integer Sequences, March 2 2013. Minor revisions, March 13 2014.

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