Drinfeld Modular Polynomials in Higher Rank

Duality of Drinfeld modules and $\wp$-adic properties of Drinfeld modular forms

Let $p$ be a rational prime and $q$ a power of $p$. Let $\wp$ be a monic irreducible polynomial of degree $d$ in $\mathbf{F}_q[t]$. In this paper, we define an analogue of the Hodge-Tate map which is suitable for the study of Drinfeld modules over $\mathbf{F}_q[t]$ and, using it, develop a geometric theory of $\wp$-adic Drinfeld modular forms similar to Katz's theory in the case of elliptic modular forms. In particular, we show that for Drinfeld modular forms with congruent Fourier coefficients at $\infty$ modulo $\wp^n$, their weights are also congruent modulo $(q^d-1)p^{\lceil \log_p(n)\rcei…

From the Carlitz exponential to Drinfeld modular forms

This paper contains the written notes of a course the author gave at the VIASM of Hanoi in the Summer 2018. It provides an elementary introduction to the analytic naive theory of Drinfeld modular forms for the simplest 'Drinfeld modular group' GL 2 (Fq[$θ$]) also providing some perspectives of development, notably in the direction of the theory of vector modular forms with values in certain ultrametric Banach algebras.

On the action of Hecke operators on Drinfeld modular forms

In this paper we determine the explicit structure of the semisimple part of the Hecke algebra that acts on Drinfeld modular forms of full level modulo T . We use computations of the Hecke action modulo T to find Drinfeld modular forms that cannot be eigenforms. Finally, we conjecture that the Hecke algebra that acts on Drinfeld modular forms of full level is not smooth for large weight.

近全纯Drinfeld模形式及其在CM点处的特殊值

Nearly holomorphic Drinfeld modular forms and their special values at CM points

本文提出近全纯Drinfeld模形式概念，研究Maass-Shimura算子类似物，证明CM点特殊值在自同态代数不同时代数独立，并应用于Drinfeld拟模形式的结构分析。

A Basis for the space of weakly holomorphic Drinfeld modular forms of level $T$

In this article, we explicitly construct a canonical basis for the space of certain weakly holomorphic Drinfeld modular forms for $Γ_0(T)$ (resp., for $Γ_0^+(T)$) and compute the generating function satisfied by the basis elements. We also give an explicit expression for the action of the $Θ$-operator, which depends on the divisor of meromorphic Drinfeld modular forms.

On Congruences Between Drinfeld Modular Forms

Let ${\mathbf F}_q$ denote a finite field of characteristic $p$ and let $n$ be an effective divisor on the affine line over ${\mathbf F}_q$ and let $v$ be a point on the affine line outside $n$. In this paper, we get congruences between ${\mathbb Q}_l$-valued weight two $v$-old Drinfeld modular forms and $v$-new Drinfeld modular forms of level $vn$. In order to do this, we shall first construct a cokernel torsion-free injection from a full lattice in the space of $v$-old Drinfeld modular forms of level $vn$ into a full lattice in the space of all Drinfeld modular forms of level $vn$. To get th…

Atkin-Lehner theory for Drinfeld modular forms and applications

The present paper deals with Atkin-Lehner theory for Drinfeld modular forms. We provide an equivalent definition of $\mathfrak{p}$-newforms (which makes computations easier) and commutativity results between Hecke operators and Atkin-Lehner involutions. As applications we show a criterion for a direct sum decomposition of cusp forms, we exibit $\mathfrak{p}$-newforms arising from lower levels and we provide $\mathfrak{p}$-adic Drinfeld modular forms of level greater than 1.

关于任意秩Drinfeld模形式的偏导数

On the partial derivatives of Drinfeld modular forms of arbitrary rank

本文研究了Drinfeld模形式在任意秩下的偏导数性质，提出了一种推广Gekeler在秩二情况下的微分算子，并展示了包含所有满模群Drinfeld模形式的有限生成代数在偏导数下的稳定性。

On certain families of Drinfeld quasi-modular forms

The aim of this paper is to describe some partial advances in the solution of the following two problems. Find the maximal order of vanishing at infinity of a non-zero Drinfeld quasi-modular form of given weight. Determine differential properties of a Drinfeld quasi-modular form of given weight and depth with maximal order of vanishing at infinity.

关于任意秩的解析狄利克雷模形式在CM点处的特殊值

On special values of meromorphic Drinfeld modular forms of arbitrary rank at CM points

本文研究了任意秩解析狄利克雷模形式在CM点处的特殊值，并在特定条件下证明其代数独立性，扩展了Chang在秩为二情况下的研究成果。

On Congruences and Linear relations for Drinfeld modular forms of level $Γ_0(T)$, arbitrary type

In \cite{Cho09}, Choi studied congruences of coefficients (modulo $T^q-T$) for Drinfeld modular forms of level $Γ_0(T)$, trivial type and the linear relations between the initial coefficients of those. In this article, we generalize these results for level $Γ_0(T)$, arbitrary type.

On Drinfeld modular forms of higher rank III: The analogue of the k/12-formula

Continuing the work of \cite{7} and \cite{8}, we derive an analogue of the classical "$k/12$-formula" for Drinfeld modular forms of rank $r \geq 2$. Here the vanishing order $ν_ω(f)$ of one modular form at some point $ω$ of the complex upper half-plane is replaced by the intersection multiplicity $ν_{\bo}(f_1,\ldots,f_{r-1})$ of $r-1$ independent Drinfeld modular forms at some point $\bo$ of the Drinfeld symmetric space $\OM^r$. We apply the formula to determine the common zeroes of $r-1$ consecutive Eisenstein series $E_{q^{i}-1}$, where $n-r<i<n$ for some $n \geq r$.

Drinfeld modular polynomials in higher rank II: Kronecker congruences

This is a sequel to the paper [F. Breuer, H.-G. Rück, Drinfeld modular polynomials in higher rank, J. Number Theory 129 (2009), 59-83.], in which we introduced Drinfeld modular polynomials of higher rank, using an analytic construction. These polynomials relate the isomorphism invariants of Drinfeld F_q[T]-modules of rank r\geq 2 linked by isogenies of a specified type. In the current paper, we give an algebraic construction of greater generality, and prove a generalization of the Kronecker congruences relations, which describe what happens when modular polynomials associated to P-isogenies ar…

Drinfeld modular forms of arbitrary rank, Part III: Examples

This is the third part of a series of articles providing a foundation for the theory of Drinfeld modular forms of arbitrary rank. In the present article we construct and study some examples of Drinfeld modular forms. In particular we define Eisenstein series, as well as the action of Hecke operators upon them, coefficient forms and discriminant forms. In the special case A=F_q[t] we show that all modular forms for GL_r(Γ(t)) are generated by certain weight one Eisenstein series, and all modular forms for GL_r(A) and SL_r(A) are generated by certain coefficient forms and discriminant forms. We …

高层Drinfeld拟模形式

Drinfeld Quasi-Modular Forms of Higher Level

该研究探讨同余子群的Drinfeld拟模形式向量空间结构，通过E展开和超导数表示其结构，引入双斜线算子定义Hecke算子，刻画本征形式并给出Γ₀(𝔫)子群下Hecke作用于E展开的显式公式。

Modular Invariant of Rank 1 Drinfeld Modules and Class Field Generation

The modular invariant of rank 1 Drinfeld modules is introduced and used to formulate and prove an exact analog of the Weber-Fueter theorem for global function fields. The main ingredient in the proof is a version of Shimura's Main Theorem of Complex Multiplication for global function fields, which is also proved here.

The structure of Drinfeld modular forms of level $Γ_0(T)$ and applications

In this article, we describe the structure of the $R$-algebra of Drinfeld modular forms $M(Γ_0(T))_R$ (resp., $M^0(Γ_0(T))_R$) of level $Γ_0(T)$ and the structure of mod-$\p$ reduction of $M_{\mfp}^0(Γ_0(T))$ for $\p \neq (T)$. As a result, we are able to study the properties of the weight filtration for $M_{k,l}(Γ_0(T))$. Finally, we prove a result on mod-$\p$ congruences for Drinfeld modular forms of level $Γ_0(\p T)$ for $\p \neq (T)$.

Estimating the order of vanishing at infinity of Drinfeld quasi-modular forms

We introduce and study certain deformations of Drinfeld quasi-modular forms by using rigid analytic trivialisations of corresponding Anderson's t-motives. We show that a sub-algebra of these deformations has a natural graduation by the group Z^2 x Z/(q-1)Z and an homogeneous automorphism, and we deduce from this and other properties multiplicity estimates.

On Drinfeld modular forms of higher rank and quasi-periodic functions

In the present paper, we introduce a special function on the Drinfeld period domain $Ω^{r}$ for $r\geq 2$ which gives the false Eisenstein series of Gekeler when $r=2$. We also study its functional equation and relation with quasi-periodic functions of a Drinfeld module as well as transcendence of its values at CM points.

Drinfeld模曲线约化下的CM点渐近分布

Asymptotic distribution of CM points on the reduction of the Drinfeld modular curve

研究全球函数域上CMDrinfeld模在Drinfeld模曲线分析约化不可约分量中的渐近分布，利用建筑映射和布鲁hat-蒂茨树商的邻接算子谱分解性质。

On mod $\mathfrak{p}$ congruences for Drinfeld modular forms of level $\mathfrak{p}\mathfrak{m}$

In~\cite{CS04}, Calegari and Stein studied the congruences between classical cusp forms $S_k(Γ_0(p))$ of prime level and made several conjectures about them. In~\cite{AB07} (resp., ~\cite{BP11}) the authors proved one of those conjectures (resp., their generalizations). In this article, we study the analogous conjecture and its generalizations for Drinfeld modular forms.

Generalized Jacobians of modular and Drinfeld modular curves

We consider the generalized Jacobian $\widetilde{J}$ of the modular curve $X_0(N)$ of level $N$ with respect to a reduced divisor consisting of all cusps. Supposing $N$ is square free, we explicitly determine the structure of the $\mathbb{Q}$-rational torsion points on $\widetilde{J}$ up to $6$-primary torsion. The result turns out to be very different from the case of prime power level previously studied by Yang and the second author. We also obtain an analogous result for Drinfeld modular curves. Our proof relies on similar results for classical Jacobians due to Ohta, Papikian and the first …

On Drinfeld modular forms of higher rank II

We show that the absolute value $|f|$ of an invertible holomorphic function $f$ on the Drinfeld symmetric space $\OM^r$ $(r \geq 2)$ is constant on fibers of the building map to the Bruhat-Tits building $\MB\MT$. Its logarithm $\log|f|$ is an affine map on the realization of $\MB\MT$. These results are used to study the vanishing loci of modular forms (coefficient forms, Eisenstein series, para-Eisenstein series) and to determine their images in $\MB\MT$.

Good families of Drinfeld modular curves

In this paper we investigate examples of good and optimal Drinfeld modular towers of function fields. Surprisingly, the optimality of these towers has not been investigated in full detail in the literature. We also give an algorithmic approach on how to obtain explicit defining equations for some of these towers and in particular give a new explicit example of an optimal tower over a quadratic finite field.

层级 $T$ 的 Drinfeld 模多项式

Drinfeld modular polynomials of level $T$

本文研究了参数化秩 $r\geq 2$ 的 Drinfeld 模间 $T$-同源的模多项式，通过显式分类同源，导出了系数 $T$-次数的显式界限，并获得了多项式高度的精确表达式。

Vectorial Drinfeld modular forms over Tate algebras

In this text, we develop the theory of vectorial modular forms with values in Tate algebras introduced by the first author, in a very special case (dimension two, for a very particular representation of Γ := GL 2 (Fq[$theta$])). Among several results that we prove here, we determine the complete structure of the modules of these forms, we describe their specializations at roots of unity and their connection with Drinfeld modular forms for congruence subgroups of Γ and we prove that the modules generated by these forms are stable under the actions of Hecke operators.

A-expansions of Drinfeld modular forms

We introduce the notion of Drinfeld modular forms with $A$-expansions, where instead of the usual Fourier expansion in $t^n$ ($t$ being the uniformizer at `infinity'), parametrized by $n \in \mathbb{N}$, we look at expansions in $t_a$, parametrized by $a \in A = \Fq [T]$. We construct an infinite family of eigenforms with $A$-expansions. Drinfeld modular forms with $A$-expansions have many desirable properties that allow us to explicitly compute the Hecke action. The applications of our results include: (i) various congruences between Drinfeld eigenforms; (ii) the computation of the eigensyste…

On the Eisenstein ideal of Drinfeld modular curves

Let $\goth E(\goth p)$ denote the Eisenstein ideal in the Hecke algebra $\Bbb T(\goth p)$ of the Drinfeld modular curve $X_0(\goth p)$ parameterizing Drinfeld modules of rank two over $\Bbb F_q[T]$ of general characteristic with Hecke level $\goth p$-structure, where $\goth p\triangleleft\Bbb F_q[T]$ is a non-zero prime ideal. We prove that the characteristic $p$ of the field $\Bbb F_q$ does not divide the order of the quotient $\Bbb T(\goth p)/\goth E(\goth p)$ and the Eisenstein ideal $\goth E(\goth p)$ is locally principal.

On Drinfeld modular forms of higher rank IV: Modular forms with level

We construct and study a natural compactification $\overline{M}^r(N)$ of the moduli scheme $M^r(N)$ for rank-$r$ Drinfeld $\F_q[T]$-modules with a structure of level $N \in \F_q[T]$. Namely, $\overline{M}^r(N) = {\rm Proj}\,{\bf Eis}(N)$, the projective variety associated with the graded ring ${\bf Eis}(N)$ generated by the Eisenstein series of rank $r$ and level $N$. We use this to define the ring ${\bf Mod}(N)$ of all modular forms of rank $r$ and level $N$. It equals the integral closure of ${\bf Eis}(N)$ in their common quotient field $\widetilde{\MF}_r(N)$. Modular forms are characterized…

Compactification of Drinfeld modular varieties and Drinfeld Modular Forms of Arbitrary Rank

We give an abstract characterization of the Satake compactification of a general Drinfeld modular variety. We prove that it exists and is unique up to unique isomorphism, though we do not give an explicit stratification by Drinfeld modular varieties of smaller rank which is also expected. We construct a natural ample invertible sheaf on it, such that the global sections of its $k$-th power form the space of (algebraic) Drinfeld modular forms of weight $k$. We show how the Satake compactification and modular forms behave under all natural morphisms between Drinfeld modular varieties; in particu…

任意秩Drinfeld模形式的一族Hecke本征形式

A family of Hecke eigenforms for Drinfeld modular forms of arbitrary rank

本文针对任意秩情形，利用特定表示发展向量Drinfeld模形式理论，以构造由扭曲艾森斯坦级数行列式给出的尖点Drinfeld-Hecke本征形式无穷族。

Familles de formes modulaires de Drinfeld pour le groupe général linéaire

Let $F$ be a function field over $\mathbb{F}_q$, $A$ its ring of regular functions outside a place $\infty$ and $\mathfrak{p}$ a prime ideal of $A$. First, we develop Hida theory for Drinfeld modular forms of rank $r$ which are of slope zero for a suitably defined Hecke operator $\mathrm{U}_{\mathfrak{p}}$. Second, we show the existence in the finite slope case of families of Drinfeld modular forms varying continuously with respect to the weight. Finally, we show a classicity result: an overconvergent Drinfeld modular form of sufficiently small slope with respect to the weight is a classical D…

论高秩Drinfeld模形式VII：边界处的展开

On Drinfeld modular forms of higher rank VII: Expansions at the boundary

本文研究秩r≥2的Drinfeld模形式沿模簇边界的展开，建立判别式乘积公式，用部分zeta函数描述消失阶，并通过Eisenstein级数的线性无关性分解模形式空间，刻画边界条件。

The André-Oort Conjecture for Drinfeld Modular Varieties

We consider the analogue of the André-Oort conjecture for Drinfeld modular varieties which was formulated by Breuer. We prove this analogue for special points with separable reflex field over the base field by adapting methods which were used by Klingler and Yafaev to prove the André-Oort conjecture under the generalized Riemann hypothesis in the classical case. Our result extends results of Breuer showing the correctness of the analogue for special points lying in a curve and for special points having a certain behaviour at a fixed set of primes.

函数域中Ligozat定理的Drinfeld模单位 analogue

A function field analogue of Ligozat's theorem for Drinfeld modular units

本文研究了函数域中Drinfeld模单位的性质，并通过构造映射建立了有理尖点divisor class group的指数上界。

On Drinfeld modular forms of higher rank VI: The simplicial complex associated with a coefficient form

The coefficient forms \( {}_{a} \ell_{k} \) and the para-Eisenstein series \(α_{k}\) are simplicial Drinfeld modular forms. We study the attached simplicial complexes \(\mathcal{BT}^{r}( {}_{a} \ell_{k})\) and \(\mathcal{BT}^{r}(α_{k})\), which are full subcomplexes of the Bruhat-Tits building \(\mathcal{BT}^{r}\) of \( \mathrm{PGL}(r, K_{\infty})\). They are connected (if the rank \(r\) is larger than 2), strongly equidimensional of codimension 1 in \(\mathcal{BT}^{r}\), boundaryless, and satisfy a symmetry property under the non-trivial involution of the Dynkin diagram \(A_{r-1}\).

关于 SL(2) 的 Drinfeld 模曲线

On Drinfeld modular curves for SL(2)

本文研究 SL(2) 的 Hecke 同余子群对应的 Drinfeld 模曲线，用 Gekeler–Nonnengardt 组合方法给出亏格公式，并计算亏格为 1 时的 Weierstrass 方程。

Drinfeld模多项式与Hecke像的高度

Heights of Drinfeld modular polynomials and Hecke images

本文研究了 Drinfeld 模多项式与 Hecke 像的高度问题，获得了多项式系数大小的显式上下界，并证明了其主项的渐近最优性，同时给出了秩2 Drinfeld 模 Hecke 像高度的精确估计。

The rational torsion subgroups of Drinfeld modular Jacobians and Eisenstein pseudo-harmonic cochains

Let $\frak{n}$ be a square-free ideal of $\mathbb{F}_q[T]$. We study the rational torsion subgroup of the Jacobian variety $J_0(\frak{n})$ of the Drinfeld modular curve $X_0(\frak{n})$. We prove that for any prime number $\ell$ not dividing $q(q-1)$, the $\ell$-primary part of this group coincides with that of the cuspidal divisor class group. We further determine the structure of the $\ell$-primary part of the cuspidal divisor class group for any prime $\ell$ not dividing $q-1$.

Drinfeld modular curve and Weil pairing

In this paper we describe the compactification of the Drinfeld modular curve. This compactification is analogous to the compactification of the classical modular curve given by Katz and Mazur. We show how the Weil pairing on Drinfeld modules that we defined in earlier work gives rise to a map on the Drinfeld modular curve. We introduce the Tate-Drinfeld module and show how this describes the formal neighbourhood of the scheme of cusps of the Drinfeld modular curve.

Hyperdifferential properties of Drinfeld quasi-modular forms

This article is divided in two parts. In the first part we endow a certain ring of ``Drinfeld quasi-modular forms'' for $\GL_2(\FF_q[T])$ (where $q$ is a power of a prime) with a system of "divided derivatives" (or hyperderivations). This ring contains Drinfeld modular forms as defined by Gekeler in \cite{Ge}, and the hyperdifferential ring obtained should be considered as a close analogue in positive characteristic of famous Ramanujan's differential system relating to the first derivatives of the classical Eisenstein series of weights 2, 4 and 6. In the second part of this article we prove th…

Explicit equations for Drinfeld modular towers

Elaborating on ideas of Elkies, we show how recursive equations for towers of Drinfeld modular curves $(X_0(P^n))_{n\ge 0}$ for $P\in \mathbb F_q[T]$ can be read of directly from the modular polynomial $Φ_P(X,Y)$ and how this naturally leads to recursions of depth two. Although the modular polynomial $Φ_T(X,Y)$ is not known in general, using generators and relations given by Schweizer, we find unreduced recursive equations over $\mathbb F_q(T)$ for the tower $(X_0(T^n))_{n\ge 2}$ and of a small variation of it (its partial Galois closure). Reducing at various primes, one obtains towers over fi…

Weierstrass points on the Drinfeld modular curve $X_0(\mathfrak{p})$

Consider the Drinfeld modular curve $X_0(\mathfrak{p})$ for $\mathfrak{p}$ a prime ideal of $\mathbb{F}_q[T]$. It was previously known that if $j$ is the $j$-invariant of a Weierstrass point of $X_0(\mathfrak{p})$, then the reduction of $j$ modulo $\mathfrak{p}$ is a supersingular $j$-invariant. In this paper we show the converse: Every supersingular $j$-invariant is the reduction modulo $\mathfrak{p}$ of the $j$-invariant of a Weierstrass point of $X_0(\mathfrak{p})$.

Drinfeld模曲线的高阶Hida理论

Higher Hida theory for Drinfeld modular curves

受Boxer和Pilloni启发，为Drinfeld模曲线上的线丛上同调建立高阶Hida理论，并插值Serre对偶。

The generic monodromy of Drinfeld modular varieties in special characteristic

By combining theorems of Drinfeld and Strauch, we show that the monodromy representation on the special fibre of a Drinfeld modular variety, with level not divisible by the characteristic, is surjective. We illustrate this result in the special case of Drinfeld $\mathbb{F}_q[t]$-modules in level $t$, and apply this to show that the Kronecker factors of a Drinfeld modular polynomial in rank $r$ are irreducible.

Regularity of quotients of Drinfeld modular schemes

Let $A$ be the coordinate ring of a projective smooth curve over a finite field minus a closed point. For a nontrivial ideal $I \subset A$, Drinfeld defined the notion of structure of level $I$ on a Drinfeld module. We extend this to that of level $N$, where $N$ is a finitely generated torsion $A$-module. The case where $N=(I^{-1}/A)^d$, where $d$ is the rank of the Drinfeld module,coincides with the structure of level $I$. The moduli functor is representable by a regular affine scheme. The automorphism group $\mathrm{Aut}_{A}(N)$ acts on the moduli space. Our theorem gives a class of subgroup…

Graph Laplacians, component groups and Drinfeld modular curves

Let $\frak{p}$ be a prime ideal of $\mathbb{F}_q[T]$. Let $J_0(\frak{p})$ be the Jacobian variety of the Drinfeld modular curve $X_0(\frak{p})$. Let $Φ$ be the component group of $J_0(\frak{p})$ at the place $1/T$. We use graph Laplacians to estimate the order of $Φ$ as $\mathrm{deg}(\frak{p})$ goes to infinity. This estimate implies that $Φ$ is not annihilated by the Eisenstein ideal of the Hecke algebra $\mathbb{T}(\frak{p})$ acting on $J_0(\frak{p})$ once the degree of $\frak{p}$ is large enough. We also obtain an asymptotic formula for the size of the discriminant of $\mathbb{T}(\frak{p})$…

CM德拉芬模块、自同源模形式与火山结构

CM Drinfeld Modules, Self-isogenous Modular Polynomials, and Volcano Structure

本文研究了CM德拉芬模块的自同源模形式和火山结构，提出了一种计算方法并证明了火山结构在同源图中的出现。

关于容许系数环上的近亚纯Drinfeld模形式

On nearly holomorphic Drinfeld modular forms for admissible coefficient rings

本文推广了先前工作，针对$\mathrm{GL}_2(A)$的同余子群引入了近亚纯Drinfeld模形式的概念，通过扩展德拉姆层给出了其代数与解析描述的比较同构，并证明了其在CM点处特殊值的超越性及与CM Drinfeld $A$-模周期的关联。

Drinfeld discriminant function and Fourier expansion of harmonic cochains

Let $F_\infty=\mathbb{F}_q(\!(1/T)\!)$ be the completion of $\mathbb{F}_q(T)$ at $1/T$. We develop a theory of Fourier expansions for harmonic cochains on the edges of the Bruhat-Tits building of $\mathrm{PGL}_r(F_\infty)$, $r\geq 2$, generalizing an earlier construction of Gekeler for $r=2$. We then apply this theory to study modular units on the Drinfeld symmetric space $Ω^r$ over $F_\infty$, and the cuspidal divisor groups of Satake compactifications of certain Drinfeld modular varieties. In particular, we obtain a higher dimensional analogue of a result of Ogg for classical modular curves …

The rigid analytical regulator and K_2 of Drinfeld modular curves

We evaluate a rigid analytical analogue of the Beilinson-Bloch-Deligne regulator on certain explicit elements in the K_2 of Drinfeld modular curves, constructed from analogues of modular units, and relate its value to special values of L-series using the Rankin-Selberg method.

Exceptional cases of adelic surjectivity for Drinfeld modules of rank 2

In this paper, we study the surjectivity of adelic Galois representation associated to Drinfeld $\mathbb{F}_q[T]$-modules over $\mathbb{F}_q(T)$ of rank $2$ in the cases when $q$ is even or $q=3$.

Coleman's power series and Wiles' reciprocity for rank 1 Drinfeld modules

We introduce the formalism of Coleman's power series for rank 1 Drinfeld modules and apply it to formulate and prove the analogue of Wiles' explicit reciprocity law in this setting.

The Legendre determinant form for Drinfeld modules in arbitrary rank

For each positive integer $r$, we construct a nowhere-vanishing, single-cuspidal Drinfeld modular form for $\GL_r(\FF_q[θ])$, necessarily of least possible weight, via determinants using rigid analytic trivializations of the universal Drinfeld module of rank $r$ and deformations of vectorial Eisenstein series. Along the way, we deduce that the cycle class map from de Rham cohomology to Betti cohomology is an isomorphism for Drinfeld modules of all ranks over $\FF_q[θ]$.