All Questions
150 questions
47
votes
3
answers
5k
views
Class Numbers and 163
This is a bit fluffier of a question than I usually aim for, so apologies in advance if this doesn't pass the smell test for suitability.
Likely my favorite fun fact in all of number theory is the ...
- 8,467
35
votes
0
answers
1k
views
Is there a rigid analytic geometry proof of the functional equation for the Riemann zeta function?
The adèles $\mathbb A$ arise naturally when considering the Berkovich space $\mathcal M(\mathbb Z)$ of the integers. Namely, they are the stalk $\mathbb A = (j_\ast j^{-1} \mathcal O_\mathbb Z)_p$ ...
- 63.9k
29
votes
1
answer
2k
views
What's special about the circle problem?
Let $K$ be a number field, and let
$$\zeta_{K}(s):= \sum_{0
\neq I \text{ ideal of }O_K} \frac{1}{N_{K/\mathbb{Q}}(I)^s} = \sum_{n \ge 1} \frac{a_n}{n^s}$$
be the Dedekind zeta function of $K$. The ...
- 14.6k
28
votes
4
answers
6k
views
The Riemann Hypothesis and the Langlands program
On page 263 of this book review appears the following:
Given the centrality of L-functions to the Langlands program, nothing would seem more natural (than a presentation of elementary algebraic ...
- 7,067
28
votes
1
answer
2k
views
Intuitive reason why the $j$-invariant is a cube?
Let $\tau$ be a CM point of discriminant $D$. Assume that $D$ is not divisible by $3$. Then $j(\tau)$ is an algebraic integer of degree equal to the class number $h(D)$. Let $ \gamma_2(\tau)=j(\tau)^{...
- 2,375
24
votes
2
answers
1k
views
Elementary congruences and L-functions
In a recent article, Emmanuel Lecouturier proves a generalization of the following surprising result: for a Mersenne prime $N = 2^p - 1 \ge 31$, the element
$$ S = \prod_{k=1}^{\frac{N-1}2} k^k $$
...
- 32.6k
23
votes
3
answers
2k
views
Why are values of Eisenstein $E_2^*$ algebraic integers?
I'm looking for a proof that the following term is an algebraic integer whenever $\tau_N=\frac{N+\sqrt{-N}}{2}$ is a quadratic irrationality with class number $1$:
$$A_N:=\sqrt{-N}\cdot\frac{E_2(\...
- 598
22
votes
3
answers
2k
views
Hecke equidistribution
For a prime $p\equiv 1\pmod{4}$, we can write $p=a^2+b^2=N(a+bi)$. Therefore
$$
a+bi=p^{1/2}e^{i\varphi}
$$
where $\varphi\in [0,2\pi]$. I know that Hecke proved that $\varphi$ is equidistributed. I ...
- 2,508
19
votes
2
answers
2k
views
Applications of Artin's holomorphy conjecture
I wonder why the Artin conjecture is so important. The only reason I could figure out is that one could use the holomorphy of Artin L-series and Weil's converse theorem to show modularity of two-...
user19475
18
votes
2
answers
1k
views
Can the Dedekind zeta function distinguish between real and imaginary quadratic number fields?
Suppose I am given a machine that gives me the coefficients $a_1$, $a_2$, $a_3$, ... of a Dirichlet series
$$\sum_1^{\infty} \frac{a_n}{n^s} $$
and assume that I know that this Dirichlet series is the ...
- 5,637
16
votes
2
answers
809
views
Multizeta function values
Francis Brown Theorem says that $\zeta(a_{1},\dots ,a_{r})$ the multi-zeta value of weight $N=a_{1}+\dots +a_{r}$ is a $\mathbb{Q}$-linear combination of elements of the set $S=\{\zeta(a_{1},\dots, ...
- 641
15
votes
1
answer
1k
views
Chebotarev density theorem for $k$-almost primes
Consider a finite Galois extension $L$ of $\mathbb Q$, of Galois group $G$. Let $k \geq 1$ be a fixed integer. Let $D$ be a subset of $G^k$ invariant by conjugation and by the natural action of the ...
- 26k
15
votes
1
answer
495
views
Is the number of representations as the sum of two elements of a polynomial sequence always small?
Let $f(x) \in \mathbb{Z}[x]$ be a degree $d>1$ polynomial with integer coefficients. Define
$$r(n) := | \{x,y \in \mathbb{Z} : f(x)+f(y) = n \}|. $$
My question is:
Is it true that $r(n)...
- 13k
14
votes
1
answer
582
views
Growth of $\zeta_{\mathbf Q[\cos(\frac{\pi}{2^{n+1}})]}(2)$
Let $K_n$ be the field $\mathbf Q[\cos(\frac{\pi}{2^{n+1}})]$ (the real subfield of the cyclotomic field $\mathbf Q[e^{\frac{i\pi}{2^{n+1}}}]$).
Is there anything known about the growth of the ...
- 1,980
14
votes
1
answer
497
views
Geometric Mean of $L(1,\chi)$ for quadratic Dirichlet characters
Let $S = \{D_1, D_2, D_3, \ldots \}$ be the set of all prime discriminants
(or positive prime discriminants) of quadratic number fields. For such a
discriminant let $\chi_j(n) = (\frac{D_j}n)$ be ...
- 32.6k
14
votes
0
answers
446
views
Is every prime $q$ of the form $x^2 + py^2$ for some prime $p<q$?
For every odd prime $q \geq 3$, does there exist a prime $p < q$ and integers $x,y$ such that
$$\displaystyle x^2 + py^2 = q?$$
One can easily show that all primes $q \not \equiv -1 \pmod{3}$ can ...
- 26.9k
13
votes
2
answers
1k
views
Question about a lesser-known "class number formula" of Gauss
My question refers to article 301 of section 5 of Gauss's D. A. - there Gauss gives an asymptotic formula for the mean number of classes of forms with positive discriminant ($D>0$):
$$h(D) = \frac{...
- 2,099
13
votes
2
answers
2k
views
Why is $\frac{\sqrt{6}}{32}(29 + \sqrt{145}) \approx \pi$ ?
Apologies in advance if this is a stupid question; also, disclaimer: this is purely for fun; but:
Why is $\frac{\sqrt{6}}{32}(29 + \sqrt{145})$ such a good approximation to $\pi$?
(Correct to 8 ...
- 1,990
13
votes
2
answers
590
views
What are Mean Values of Ideal Densities in Galois Extensions?
In an unfinished (and as of now unpublished) article intended for the encyclopedia of mathematics, Arnold Scholz wrote:
"Classifying extensions according to the Galois group
of their normal closure ...
- 32.6k
12
votes
1
answer
1k
views
Where should I learn about the p-adic L-functions of elliptic curves?
Where is the best place to learn about the p-adic L-functions of Elliptic Curves? Doing a bit of research I have found books like "An Introduction to Cyclotomic Fields" by Washington, but ...
- 2,902
12
votes
1
answer
2k
views
Artin conjecture on L-functions
Artin conjecture on Artin $L$-functions asserts that the Artin $L$-function $L(\rho,s)$ of a non-trivial irreducible representation $\rho$ of the Galois group $\Gamma$ of a number field admits ...
user95222
11
votes
1
answer
2k
views
Elementary proof of a special case of Chebotarev's density theorem
A special case of Cheboratev's density theorem states that, for $K/\mathbb{Q}$ a Galois number field of degree $n$, then the rational primes that split completely in $K$ have density $1/n$.
Is there ...
- 323
11
votes
1
answer
1k
views
Upper bounds for regulators of real quadratic fields
We have an elementary sharp lower bound for the regulator of a real quadratic field as a function of the discriminant
$$R\geq \tfrac{1}{2}(\sqrt{d-4}+\sqrt{d})$$
It is sharp because the equality ...
- 17.6k
10
votes
2
answers
1k
views
Are the ideles literally a Picard group?
I understand that in the number field / function field analogy, the ideles $\mathbb I_K$ of a number field $K$ are supposed to be analogous to the Picard group of a function field.
Question: Is this ...
- 63.9k
10
votes
1
answer
841
views
Infinitely many primes that split completely in an arithmetic progression
Let $d \geq 1$ be an integer. Dirichlet's theorem on arithmetic progression implies that the arithmetic progression $a, a+d, a+2d, \ldots$ contains infinitely many primes if and only if $\gcd(a,d)=1$.
...
- 103
10
votes
1
answer
398
views
Vinogradov-Korobov prime number theorem for number fields
Without assuming the Riemann hypothesis, the traditional error bound of the prime-counting function $\pi(x)$ is $O(x\exp(-c(\log(x))^{1/2}))$. As shown by the Wikipedia page for the Landau prime ...
- 211
10
votes
1
answer
1k
views
Reference for the odd dihedral case of Artin's conjecture
The example that Matt Emerton cited here prompted me to become interested in how one proves that odd two dimensional dihedral Galois representation are modular. This is the first case of the strong ...
- 7,062
9
votes
2
answers
902
views
How to compute with the Stark conjectures?
I would like a convenient basis for the elements of a fixed abelian extension $E$ of a real quadratic field $\mathbb{Q}(\sqrt{d})$. The accepted answer to this MO question suggests that the Stark ...
- 7,633
9
votes
2
answers
647
views
On bounds for idoneal integer
What is the best known lower bound and upper bound known for such a number if it exists and have there been any attempts (computational including) to eliminate the existence of such a number in known ...
user76479
9
votes
1
answer
287
views
Algebraicity of a ratio of values of the Gamma function
The following ratio:
$$\frac{\Gamma(2/5)^3}{\pi\Gamma(1/5)}$$
has kept appearing in my research, and the only thing I know about its value is that it is $\cong 0.7567213$, whence the following two ...
- 1,001
9
votes
1
answer
235
views
Are the class numbers of $\mathbb{Q}(\cos(2\pi / m))$ $O(m^n)$ for some fixed $n$?
Question: Are the class numbers of $\mathbb{Q}(\cos(\frac{2\pi}m))$ $O(m^n)$ for some fixed $n$?
Evidences (e.g. a recent paper) showing that the question above is open are also OK.
Remark: If such $n$...
- 9,501
9
votes
1
answer
1k
views
Functional equation Dedekind zeta function
I'd like to know to what point is it possible to generalize
this method
for obtaining the functional equation for the Dedekind zeta function $\zeta_K(s)$ of a number field ?
Let $\mathfrak{C}$ be ...
- 3,403
9
votes
1
answer
787
views
Gauss sums for general number fields
There is a wide litterature for the classical Gauss sums. For $\chi$ a primitive Dirichlet character modulo $N$, it is given by
$$\tau(\chi) = \sum_{n \text{ mod } N} \chi(n) \exp(2i\pi n/N).$$
An ...
- 5,424
9
votes
0
answers
267
views
How small may the discriminant of an $S_d$-field be?
In every degree $d$, the Galois closure of the typical number field has the maximal possible Galois group $S_d$. Denote by $f(d)$ the least absolute value of a discriminant of an $S_d$-field of degree ...
- 13.8k
8
votes
1
answer
868
views
Brauer–Siegel's Theorem and application
$\newcommand\underto[1]{\xrightarrow[#1]{}}$Brauer–Siegel's Theorem says that if we consider an infinite sequence of number fields $K_i/\mathbb{Q}$ such that $$\frac{[K_i:\mathbb{Q}]}{\log{|D_i|}}\...
- 103
8
votes
1
answer
790
views
Gauss - Dirichlet class number formula
Let $p=8k+3$ be a prime. Then the class number of the imaginary quadratic field $\mathbb Q(\sqrt{-p})$ is given by
$$h(-p)=\frac 13\sum_{k=1}^{\frac{p-1}{2}}\left(\frac kp \right).$$ While this is ...
- 2,375
8
votes
2
answers
973
views
Easiest way to see that $\zeta_{\mathbb{Z}[i]}(s) = \zeta(s) L(s, \chi)$?
As the question suggests, what is the easiest way to see that$$\zeta_{\mathbb{Z}[i]}(s) = \zeta(s)L(s, \chi)?$$Here, $\chi$ is the homomorphism $(\mathbb{Z}/4\mathbb{Z})^\times \to \mathbb{C}^\times$ ...
user75660
8
votes
1
answer
726
views
Hecke characters and Conductors
Motivation: Let $\ell$ be an odd prime. There is a conductor-preserving correspondence between primitive Dirichlet characters of order $\ell$
and cyclic, degree $\ell$ number fields $K/\mathbb{Q}$.
...
- 998
7
votes
3
answers
911
views
Does the equation $x^2+x=a$ have an integer solution?
I am writing a paper on the topological structure of the Golomb space (defined here) and arrived to the following question:
Question 1. Is it true that for a number $a\in\mathbb N$ the equation $x^2+...
- 41.9k
7
votes
1
answer
635
views
Is there a Chebotarev‘s theorem for non-Galois extension over Q？
For a Galois extension $K/\mathbb{Q}$, the Chebotarev Density Theorem predicts the density of primes with a certain splitting type.
I'm wondering if there is a similar result for non-Galois extension?
...
- 547
7
votes
1
answer
389
views
Existence of imaginary quadratic fields of class numbers coprime to $p$ with prescribed splitting behaviour of $p$
Let $x\in\{\text{totally ramified, inert, totally split}\}.$
If $p\geq 5$ is a prime, are there infinitely many imaginary quadratic fields $K=\mathbb{Q}(\sqrt{-d})$ of class number coprime to $p$ so ...
- 1,805
7
votes
1
answer
400
views
Splitting of small primes in number fields generated by the torsion of elliptic curves
Suppose $E/\mathbb Q$ is a non CM elliptic curve and we look at the number field $K_d$ generated by the $d$-torsion of $E$. What is known about the (complete) splitting of small primes in $K_d$?
More ...
- 7,746
7
votes
1
answer
406
views
Averaging Chebotarev's density theorem over families of number fields
The Chebotarev density theorem is one of the most celebrated and important results in number theory. We state the following version: for a number field $K$, Galois over $\mathbb{Q}$ with Galois group (...
- 26.9k
7
votes
3
answers
768
views
Sato-Tate and the angles of split primes
I was reading this blog by Evan Chen about complex multiplication. He's discussing Sato-Tate Conjecture. We can have elliptic curve $E/\mathbb{Q}$ and solve it over finite fields.
\begin{eqnarray*}
...
- 22.8k
7
votes
0
answers
162
views
Relation between the additive Haar measure on $(K,+)$ and the multiplicative Haar measure on $K^{*}$ for a global field $K$
The following question comes from my studying of Alain Connes's paper Trace Formula in Noncommutative Geometry and the Zeros of the Riemann Zeta Function. In it, on p. 11, Connes notes that if $K$ is ...
- 1,805
7
votes
0
answers
118
views
Upper bound on $\#\{p \leq B :\#E(\mathbb{F}_p) \equiv a \mod b\}$ for large $b$
Let $E$ be a fixed elliptic curve over $\mathbb{Q}$. Is there a good upper bound on $\#\{p \leq B :\#E(\mathbb{F}_p) \equiv a \mod b\}$ when $b$ is large (maybe around $\sqrt{B}$)? I don't mind ...
- 270
6
votes
1
answer
459
views
Growth of Class Numbers
There is a classical formula stating:
Let $K$ be a number field with ring of integers $\mathcal{O}_K\subseteq K$ and
let $\mathcal{O}\subseteq \mathcal{O}_K$ be any non-maximal order with conductor $...
- 443
6
votes
1
answer
499
views
Understanding Sylvester' s $1871$ paper of primes in arithmetic progression of the forms $4n+3$ and $6n+5$
The following is the proof of infinitude of primes in arithmetic progression of the form $4n+3$ and $ 6n+5$ done by Sylvester in $1871$ in his paper "On the theorem that an arithmetical progression ...
- 233
6
votes
1
answer
286
views
Functional equation of twisted triple product L-function
Let $\mathbb{E}=E_1\times E_2\times E_3$ denote the product of three elliptic curves over $\mathbb{Q}$ of prime level $p$ and consider the $p$-adic Galois representation $$V_p(\mathbb{E})=H^1_{et}(E_{...
- 83
6
votes
1
answer
183
views
Explicit evaluation of the derivatives of $p$-adic Gamma function at 0
The definition of the $p$-adic Gamma function $\Gamma_p(x)$ for an odd prime number $p$ can be found in the book "A Course in $p$-adic analysis" by A. M. Robert. While the construction of $\log \...
- 2,971