On the divisibility of class numbers of quadratic fields and the solvability of Diophantine equations

In this paper we provide criteria for the insolvability of the Diophantine equation $x^2+D=y^n$. This result is then used to determine the class number of the quadratic field $\mathbb{Q}(\sqrt{-D})$. We also determine some criteria for the divisibility of the class number of the quadratic field $\mathbb{Q}(\sqrt{-D})$ and this result is then used to discuss the solvability of the Diophantine equation $x^2+D=y^n$

The cyclotomic Iwasawa main conjecture for Hilbert cuspforms with complex multiplication

We deduce the cyclotomic Iwasawa main conjecture for Hilbert modular cuspforms with complex multiplication from the multivariable main conjecture for CM number fields. To this end, we study in detail the behaviour of the $p$-adic $L$-functions and the Selmer groups attached to CM number fields under specialisation procedures.Comment: 83 pages, no figure

On the Iwasawa theory of CM fields for supersingular primes

The goal of this article is two-fold: First, to prove a (two-variable) main conjecture for a CM field $F$ without assuming the $p$-ordinary hypothesis of Katz, making use of what we call the Rubin-Stark $\mathcal{L}$-restricted Kolyvagin systems which is constructed out of the conjectural Rubin-Stark Euler system of rank $g$. (We are also able to obtain weaker unconditional results in this direction.) Second objective is to prove the Park-Shahabi plus/minus main conjecture for a CM elliptic curve $E$ defined over a general totally real field again using (a twist of the) Rubin-Stark Kolyvagin system. This latter result has consequences towards the Birch and Swinnerton-Dyer conjecture for $E$.Comment: 39 pages, to appear in Transactions of AMS (might slightly differ from the final published version

On the computation of the class numbers of real Abelian fields

Siirretty Doriast

On The Relative Class Number of Special Cyclotomic Fields

Let p be an odd prime, p be a primitive pth root of unity and h��p be the relative class number of the pth cyclotomic fi eld Q( p) over the rationals Q defi ned by p. The main purpose of this paper is to discuss arithmetic properties of factors of h��p for an odd prime p of the form p = 4q + 1 with q a prime

On the Iwasawa main conjectures for modular forms at non-ordinary primes

In this paper, we prove under mild hypotheses the Iwasawa main conjectures of Lei--Loeffler--Zerbes for modular forms of weight $2$ at non-ordinary primes. Our proof is based on the study of the two-variable analogues of these conjectures formulated by B\"uy\"ukboduk--Lei for imaginary quadratic fields in which $p$ splits, and on anticyclotomic Iwasawa theory. As application of our results, we deduce the $p$-part of the Birch and Swinnerton-Dyer formula in analytic ranks $0$ or $1$ for abelian varieties over $\mathbb{Q}$ of ${\rm GL}_2$-type for non-ordinary primes $p>2$

Differential principal factors and Polya property of pure metacyclic fields

Barrucand and Cohn's theory of principal factorizations in pure cubic fields $\mathbb{Q}(\sqrt[3]{D})$ and their Galois closures $\mathbb{Q}(\zeta_3,\sqrt[3]{D})$ with $3$ types is generalized to pure quintic fields $L=\mathbb{Q}(\sqrt[5]{D})$ and pure metacyclic fields $N=\mathbb{Q}(\zeta_5,\sqrt[5]{D})$ with $13$ possible types. The classification is based on the Galois cohomology of the unit group $U_N$, viewed as a module over the automorphism group $\mathrm{Gal}(N/K)$ of $N$ over the cyclotomic field $K=\mathbb{Q}(\zeta_5)$, by making use of theorems by Hasse and Iwasawa on the Herbrand quotient of the unit norm index $(U_K:N_{N/K}(U_N))$ by the number $\#(\mathcal{P}_{N/K}/\mathcal{P}_K)$ of primitive ambiguous principal ideals, which can be interpreted as principal factors of the different $\mathfrak{D}_{N/K}$. The precise structure of the group of differential principal factors is determined with the aid of kernels of norm homomorphisms and central orthogonal idempotents. A connection with integral representation theory is established via class number relations by Parry and Walter involving the index of subfield units $(U_N:U_0)$. Generalizing criteria for the Polya property of Galois closures $\mathbb{Q}(\zeta_3,\sqrt[3]{D})$ of pure cubic fields $\mathbb{Q}(\sqrt[3]{D})$ by Leriche and Zantema, we prove that pure metacyclic fields $N=\mathbb{Q}(\zeta_5,\sqrt[5]{D})$ of only $1$ type cannot be Polya fields. All theoretical results are underpinned by extensive numerical verifications of the $13$ possible types and their statistical distribution in the range $2\le D<10^3$ of $900$ normalized radicands.Comment: 30 pages, 10 sections, 6 table

An Equivariant Main Conjecture in Iwasawa Theory and Applications

We construct a new class of Iwasawa modules, which are the number field analogues of the p-adic realizations of the Picard 1-motives constructed by Deligne in the 1970s and studied extensively from a Galois module structure point of view in our recent work. We prove that the new Iwasawa modules are of projective dimension 1 over the appropriate profinite group rings. In the abelian case, we prove an Equivariant Main Conjecture, identifying the first Fitting ideal of the Iwasawa module in question over the appropriate profinite group ring with the principal ideal generated by a certain equivariant p-adic L-function. This is an integral, equivariant refinement of the classical Main Conjecture over totally real number fields proved by Wiles in 1990. Finally, we use these results and Iwasawa co-descent to prove refinements of the (imprimitive) Brumer-Stark Conjecture and the Coates-Sinnott Conjecture, away from their 2-primary components, in the most general number field setting. All of the above is achieved under the assumption that the relevant prime p is odd and that the appropriate classical Iwasawa mu-invariants vanish (as conjectured by Iwasawa.)Comment: 52 page

On the μ\mu-invariant of the cyclotomic derivative of Katz p-adic L-function

When the branch character has root number -1, the corresponding anticyclotomic Katz p-adic L-function identically vanishes. In this case, we study the $\mu$-invariant of the cyclotomic derivative of Katz p-adic L-function. As an application, this proves the non-vanishing of the anticyclotomic regulator of a self-dual CM modular form with the root number -1. The result also plays a crucial role in the recent work of Hsieh on the Eisenstein ideal approach to a one-sided divisibility of the CM main conjecture.Comment: 15 pages, revised, to appear in J. Institut Math. Jussie

Squarefree values of trinomial discriminants

The discriminant of a trinomial of the form $x^n \pm x^m \pm 1$ has the form $\pm n^n \pm (n-m)^{n-m} m^m$ if $n$ and $m$ are relatively prime. We investigate when these discriminants have nontrivial square factors. We explain various unlikely-seeming parametric families of square factors of these discriminant values: for example, when $n$ is congruent to 2 (mod 6) we have that $((n^2-n+1)/3)^2$ always divides $n^n - (n-1)^{n-1}$. In addition, we discover many other square factors of these discriminants that do not fit into these parametric families. The set of primes whose squares can divide these sporadic values as $n$ varies seems to be independent of $m$, and this set can be seen as a generalization of the Wieferich primes, those primes $p$ such that $2^{p-1}$ is congruent to 1 (mod $p^2$). We provide heuristics for the density of squarefree values of these discriminants and the density of these "sporadic" primes.Comment: 22 pages, 1 table. Minor revisions from version 1, including three new reference