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arXiv · 1511.02388

Orders of reductions of elliptic curves with many and few prime factors

Lee Troupe
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Abstract

In this paper, we investigate extreme values of $ω(E(\mathbb{F}_p))$, where $E/\mathbb{Q}$ is an elliptic curve with complex multiplication and $ω$ is the number-of-distinct-prime-divisors function. For fixed $γ> 1$, we prove that \[ \#\{p \leq x : ω(E(\mathbb{F}_p)) > γ\log\log x\} = \frac{x}{(\log x)^{2 + γ\logγ- γ+ o(1)}}. \] The same result holds for the quantity $\#\{p \leq x : ω(E(\mathbb{F}_p)) < γ\log\log x\}$ when $0 < γ< 1$. The argument is worked out in detail for the curve $E : y^2 = x^3 - x$, and we discuss how the method can be adapted for other CM elliptic curves.

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Lee Troupe. 2015-11-07. Orders of reductions of elliptic curves with many and few prime factors. https://doi.org/10.1142/s1793042117501147

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