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arXiv 1609.01630math.NT
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不定二元二次型类数的大矩与极值

Large moments and extreme values of class numbers of indefinite binary quadratic forms

Youness Lamzouri

摘要:

设$h(d)$为判别式$d$的不定二元二次型的类数,$\varepsilon_d$为相应的基本单位.本文得到了$h(d)$在正判别式$d$上的$k$阶矩的渐近公式,对$0<k\leq (\log x)^{1-o(1)}$范围内的实数$k$是一致的.这改进了Raulf的工作,他得到了一个固定正整数$k$的渐近解。我们还研究了$h(d)$的大值的分布时,$d$的根据其基本单位$\varepsilon_d$的大小排序。特别是,我们表明,这种分布的尾部具有相同的形状,类数的虚二次域的大小排序的判别式。作为这些结果的一个应用,我们证明了有许多正判别式$d$与类数$h(d)\geq (e^γ/3+o(1))\cdot\varepsilon_d (\log\log \varepsilon_d)/\log \varepsilon_d$,一个界限,我们认为是最好的可能。我们还得到了一个上限为$h(d)$是两倍大,假设广义黎曼假设。

英文摘要:

Let $h(d)$ be the class number of indefinite binary quadratic forms of discriminant $d$, and let $\varepsilon_d$ be the corresponding fundamental unit. In this paper, we obtain an asymptotic formula for the $k$-th moment of $h(d)$ over positive discriminants $d$ with $\varepsilon_d\leq x$, uniformly for real numbers $k$ in the range $0<k\leq (\log x)^{1-o(1)}$. This improves upon the work of Raulf, who obtained such an asymptotic for a fixed positive integer $k$. We also investigate the distribution of large values of $h(d)$ when the $d$'s are ordered according to the size of their fundamental units $\varepsilon_d$. In particular, we show that the tail of this distribution has the same shape as that of class numbers of imaginary quadratic fields ordered by the size of their discriminants. As an application of these results, we prove that there are many positive discriminants $d$ with class number $h(d)\geq (e^γ/3+o(1))\cdot\varepsilon_d (\log\log \varepsilon_d)/\log \varepsilon_d$, a bound that we believe is best possible. We also obtain an upper bound for $h(d)$ that is twice as large, assuming the generalized Riemann hypothesis.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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