“Can one hear the shape of a drum?” This seemingly innocent question spawned a lot of research in the early 20th century. Even though the answer is “No, we can't”, we can hear the volume. This is known as Weyl's Law. In a more modern context, we can use new methods to study similar questions. More precisely, we can study locally symmetric spaces and the algebra of invariant differential operators. Generalizing the above, we can incorporate Hecke operators and find asymptotic formulas for their traces. We study this problem in a global context, namely if the underlying group is the group of adelic points of a quasi-split, simple reductive group. Our main tool is the Arthur-Selberg trace formula. The spectral side is dealt with, utilizing a condition on the normalizing factors of certain intertwining operators. The geometric side is more complicated and needs a more refined analysis. Most importantly, the test functions need to be specifically crafted to ensure compact support on the one hand, and sufficiently strong estimates on the other. The resulting geometric side can be split according to the Bruhat decomposition and treated separately, using various methods from reduction theory to algebraic and analytic number theory.

<p>This thesis in analytic number theory consists of 3 parts and 13 individual papers.</p><p>In the first part we prove some results in Turán power sum theory. We solve a problem of Paul Erdös and disprove conjectures of Paul Turán and K. Ramachandra that would have implied important results on the Riemann zeta function.</p><p>In the second part we prove some new results on moments of the Hurwitz and Lerch zeta functions (generalized versions of the Riemann zeta function) on the critical line.</p><p>In the third and final part we consider the following question: What is the natural generalization of the classical Poisson summation formula from the Fourier analysis of the real line to the matrix group SL(2,R)? There are candidates in the literature such as the pre-trace formula and the Selberg trace formula.</p><p>We develop a new summation formula for sums over the matrix group SL(2,Z) which we propose as a candidate for the title "The Poisson summation formula for SL(2,Z)". The summation formula allows us to express a sum over SL(2,Z) of smooth functions f on SL(2,R) with compact support, in terms of spectral theory coming from the full modular group, such as Maass wave forms, holomorphic cusp forms and the Eisenstein series. In contrast, the pre-trace formula allows us to get such a result only if we assume that f is also SO(2) bi-invariant.</p><p>We indicate the summation formula's relationship with additive divisor problems and the fourth power moment of the Riemann zeta function as given by Motohashi. We prove some identities on Kloosterman sums, and generalize our main summation formula to a summation formula over integer matrices of fixed determinant D. We then deduce some consequences, such as the Kuznetsov summation formula, the Eichler-Selberg trace formula and the classical Selberg trace formula.</p>

Diese Dissertation behandelt automorphe Formen und ihre Fourierentwicklung im Rahmen der Typ IIB Stringtheorie. Besonderes Augenmerk wird auf den zehndimensionalen Fall gelegt sowie auf die torisch kompaktifizierte Theorie in sieben Raumzeitdimensionen mit jeweiligen Cremmer-Julia Symmetrien SL_2 und SL_5. Die Analyse erfolgt vorrangig über dem Adelenring mit dem Hauptergebnis einer Herleitung allgemeiner Ausdrücke für die Fourierentwicklung von Eisensteinreihen in der minimalen und nächstgrößeren (next-to-minimal) automorphen Darstellung beliebiger SL_n. / In this thesis, we study automorphic forms and their Fourier expansions in the context of type IIB string theory and its toroidal compactifications with an emphasis on the cases D = 10 and D = 7 where the Cremmer-Julia symmetry groups are SL_2 and SL_5 respectively. We work predominantly over the adeles and present general formulae for the Fourier expansions of Eisenstein series in the minimal- and next-to-minimal automorphic representations of SL_n.

This thesis in analytic number theory consists of 3 parts and 13 individual papers. In the first part we prove some results in Turán power sum theory. We solve a problem of Paul Erdös and disprove conjectures of Paul Turán and K. Ramachandra that would have implied important results on the Riemann zeta function. In the second part we prove some new results on moments of the Hurwitz and Lerch zeta functions (generalized versions of the Riemann zeta function) on the critical line. In the third and final part we consider the following question: What is the natural generalization of the classical Poisson summation formula from the Fourier analysis of the real line to the matrix group SL(2,R)? There are candidates in the literature such as the pre-trace formula and the Selberg trace formula. We develop a new summation formula for sums over the matrix group SL(2,Z) which we propose as a candidate for the title "The Poisson summation formula for SL(2,Z)". The summation formula allows us to express a sum over SL(2,Z) of smooth functions f on SL(2,R) with compact support, in terms of spectral theory coming from the full modular group, such as Maass wave forms, holomorphic cusp forms and the Eisenstein series. In contrast, the pre-trace formula allows us to get such a result only if we assume that f is also SO(2) bi-invariant. We indicate the summation formula's relationship with additive divisor problems and the fourth power moment of the Riemann zeta function as given by Motohashi. We prove some identities on Kloosterman sums, and generalize our main summation formula to a summation formula over integer matrices of fixed determinant D. We then deduce some consequences, such as the Kuznetsov summation formula, the Eichler-Selberg trace formula and the classical Selberg trace formula.

The main part of the thesis is applications of the Strong Artin conjecture to number theory. We have two applications. One is generating number fields with extreme class numbers. The other is generating extreme positive and negative values of Euler-Kronecker constants. For a given number field $K$ of degree $n$, let $\widehat{K}$ be the normal closure of $K$ with $Gal(\widehat{K}/\Bbb Q)=G.$ Let $Gal(\widehat{K}/K)=H$ for some subgroup $H$ of $G$. Then, $$ L(s,\rho,\widehat{K}/\Bbb Q)=\frac{\zeta_K(s)}{\zeta(s)} $$ where $Ind_H^G1_H = 1_G + \rho$. When $L(s,\rho)$ is an entire function and has a zero-free region $[\alpha,1] \times [-(\log N)^2, (\log N)^2]$ where $N$ is the conductor of $L(s,\rho)$, we can estimate $\log L(1,\rho)$ and $\frac{L'}{L}(1,\rho)$ as a sum over small primes: $$ \log L(1,\rho) = \sum_{p\leq(\log N)^{k}}\lambda(p)p^{-1} + O_{l,k,\alpha}(1)$$ $$ \frac{L'}{L}(1,\rho)=-\sum_{p\leq x} \frac{\lambda(p) \log{p}}{p} +O_{l,x,\alpha}(1). $$ where $0 < k < \frac{16}{1-\alpha}$ and $(\log N)^{\frac{16}{1-\alpha}} \leq x \leq N^{\frac{1}{4}}$. With these approximations, we can study extreme values of class numbers and Euler-Kronecker constants. Let $\frak{K}$ $(n,G,r_1,r_2)$ be the set of number fields of degree $n$ with signature $(r_1,r_2)$ whose normal closures are Galois $G$ extension over $\Bbb Q$. Let $f(x,t) \in \Bbb Z[t][x]$ be a parametric polynomial whose splitting field over $\Bbb Q (t)$ is a regular $G$ extension. By Cohen's theorem, most specialization $t\in \Bbb Z$ corresponds to a number field $K_t$ in $\frak{K}$ $(n,G,r_1,r_2)$ with signature $(r_1,r_2)$ and hence we have a family of Artin L-functions $L(s,\rho,t)$. By counting zeros of L-functions over this family, we can obtain L-functions with the zero-free region above. In Chapter 1, we collect the known cases for the Strong Artin conjecture and prove it for the cases of $G=A_4$ and $S_4$. We explain how to obtain the approximations of $\log (1,\rho)$ and $\frac{L'}{L}(1,\rho)$ as a sum over small primes in detail. We review the theorem of Kowalski-Michel on counting zeros of automorphic L-functions in a family. In Chapter 2, we exhibit many parametric polynomials giving rise to regular extensions. They contain the cases when $G=C_n,$ $3\leq n \leq 6$, $D_n$, $3\leq n \leq 5$, $A_4, A_5, S_4, S_5$ and $S_n$, $n \geq 2$. In Chapter 3, we construct number fields with extreme class numbers using the parametric polynomials in Chapter 2. In Chapter 4, We construct number fields with extreme Euler-Kronecker constants also using the parametric polynomials in Chapter 2. In Chapter 5, we state the refinement of Weil's theorem on rational points of algebraic curves and prove it. The second topic in the thesis is about simple zeros of Maass L-functions. We consider a Hecke Maass form $f$ for $SL(2,\Bbb Z)$. In Chapter 6, we show that if the L-function $L(s,f)$ has a non-trivial simple zero, it has infinitely many simple zeros. This result is an extension of the result of Conrey and Ghosh.

The main part of the thesis is applications of the Strong Artin conjecture to number theory. We have two applications. One is generating number fields with extreme class numbers. The other is generating extreme positive and negative values of Euler-Kronecker constants. For a given number field $K$ of degree $n$, let $\widehat{K}$ be the normal closure of $K$ with $Gal(\widehat{K}/\Bbb Q)=G.$ Let $Gal(\widehat{K}/K)=H$ for some subgroup $H$ of $G$. Then, $$ L(s,\rho,\widehat{K}/\Bbb Q)=\frac{\zeta_K(s)}{\zeta(s)} $$ where $Ind_H^G1_H = 1_G + \rho$. When $L(s,\rho)$ is an entire function and has a zero-free region $[\alpha,1] \times [-(\log N)^2, (\log N)^2]$ where $N$ is the conductor of $L(s,\rho)$, we can estimate $\log L(1,\rho)$ and $\frac{L'}{L}(1,\rho)$ as a sum over small primes: $$ \log L(1,\rho) = \sum_{p\leq(\log N)^{k}}\lambda(p)p^{-1} + O_{l,k,\alpha}(1)$$ $$ \frac{L'}{L}(1,\rho)=-\sum_{p\leq x} \frac{\lambda(p) \log{p}}{p} +O_{l,x,\alpha}(1). $$ where $0 < k < \frac{16}{1-\alpha}$ and $(\log N)^{\frac{16}{1-\alpha}} \leq x \leq N^{\frac{1}{4}}$. With these approximations, we can study extreme values of class numbers and Euler-Kronecker constants. Let $\frak{K}$ $(n,G,r_1,r_2)$ be the set of number fields of degree $n$ with signature $(r_1,r_2)$ whose normal closures are Galois $G$ extension over $\Bbb Q$. Let $f(x,t) \in \Bbb Z[t][x]$ be a parametric polynomial whose splitting field over $\Bbb Q (t)$ is a regular $G$ extension. By Cohen's theorem, most specialization $t\in \Bbb Z$ corresponds to a number field $K_t$ in $\frak{K}$ $(n,G,r_1,r_2)$ with signature $(r_1,r_2)$ and hence we have a family of Artin L-functions $L(s,\rho,t)$. By counting zeros of L-functions over this family, we can obtain L-functions with the zero-free region above. In Chapter 1, we collect the known cases for the Strong Artin conjecture and prove it for the cases of $G=A_4$ and $S_4$. We explain how to obtain the approximations of $\log (1,\rho)$ and $\frac{L'}{L}(1,\rho)$ as a sum over small primes in detail. We review the theorem of Kowalski-Michel on counting zeros of automorphic L-functions in a family. In Chapter 2, we exhibit many parametric polynomials giving rise to regular extensions. They contain the cases when $G=C_n,$ $3\leq n \leq 6$, $D_n$, $3\leq n \leq 5$, $A_4, A_5, S_4, S_5$ and $S_n$, $n \geq 2$. In Chapter 3, we construct number fields with extreme class numbers using the parametric polynomials in Chapter 2. In Chapter 4, We construct number fields with extreme Euler-Kronecker constants also using the parametric polynomials in Chapter 2. In Chapter 5, we state the refinement of Weil's theorem on rational points of algebraic curves and prove it. The second topic in the thesis is about simple zeros of Maass L-functions. We consider a Hecke Maass form $f$ for $SL(2,\Bbb Z)$. In Chapter 6, we show that if the L-function $L(s,f)$ has a non-trivial simple zero, it has infinitely many simple zeros. This result is an extension of the result of Conrey and Ghosh.

Les principaux résultats obtenus dans ce travail concernent l’existence et l’unicité des solutions de différents types de l’équation de Liénard forcée et des résultats de dépendance pour les solutions S-asymptotiquement w-périodiques d’équations d’évolution. Pour réaliser notre objectif, nous utilisons des outils d’analyse fonctionnelle non linéaire et des résultats sur des équations linéaire. / No English summary available.

Let $G$ be a locally compact group (usually a reductive algebraic group over an algebraic number field $F$). The main aim of the theory of Automorphic Forms is to understand the right regular representation of the group $G$ on the space $L^{2}(\Gamma \ G)$ for certain \emph{nice} closed subgroups $\Gamma$. Usually, $\Gamma$ is taken to be a lattice or even an arithmetic subgroup. In the case of uniform lattices, the space $L^{2}(\Gamma \ G)$ decomposes into a direct sum of irreducible unitary representations of the group $G$ with each such representation $\pi$ occurring with a \emph{finite} multiplicity $m(\Gamma, \pi)$. It seems quite difficult to obtain an explicit formula for this multiplicity; however, the limiting behaviour of these numbers in case of certain \emph{nice} sequences of subgroups $(\Gamma_{n})_{n}$ seems more tractable. We study this problem in the global set-up where $G$ is the group of adelic points of a reductive group defined over the field of rational numbers and the relevant subgroups are the maximal compact open subgroups of $G$. As is natural and traditional, we use the Arthur trace formula to analyse the multiplicities. In particular, we expand the geometric side to obtain the information about the spectral side---which is made up from the multiplicities $m(\Gamma, \pi)$. The geometric side has a contributions from various conjugacy classes, most notably from the unipotent conjugacy class. It is this \emph{unipotent} contribution that is the subject of Part III of this thesis. We estimate the contribution in terms of level of the maximal compact open subgroup and make conclusions about the limiting behaviour. Part IV is then concerned with the spectral side of the trace formula where we show (under certain conditions) that the trace of the discrete part of the regular representation is the only term that survives in the limit.

Cette thèse est consacrée à l'étude des représentations automorphes algébriques des groupes linéaires découvertes par Chenevier-Renard. On s'intéresse plus particulièrement à leurs paramètres de Satake. Pour cela, nous utilisons la théorie d'Arthur afin de faire apparaître ces représentations par le biais de représentations automorphes discrètes des groupes spéciaux orthogonaux de réseaux bien choisis. Ensuite, on détermine des propriétés d'opérateurs de Hecke agissant sur ces mêmes réseaux, ce qui nous donne de nombreuses informations sur ces paramètres de Satake. On arrive notamment à déterminer la trace dans la représentation standard de nombreux paramètres de Satake des représentations algébriques évoquées, dont les poids peuvent être arbitrairement grands. Ces résultats nous permettent aussi de déterminer de nombreux opérateurs de Hecke, associés aux voisinage de Kneser, vus comme endomorphismes agissant sur les classes d'isomorphisme des réseaux pairs de déterminant 2 en dimension 23 ou 25. / In this these we study the different algebraic automorphic representations discovered by Chenevier-Renard. We focus more particularly on their Satake parameters. To do so, we use Arthur's theory, which enables us to see these representations through discrete automorphic representations for the special orthogonal group of well chosen lattices. Afterwards, we can compute some properties of Hecke operators acting on these lattices. This gives us a lot of information on these Satake parameters. In particular, we can determine the trace in the standard representation for many of these algebraic representations, which weight can be arbitrarily high. These results also enable us to compute many Hecke operators, connected to the notion of neighbourhood developed by Kneser, seen as linear operators acting on the classes of isomorphism of even lattices with determinant 2 in dimension 23 or 25.

Cette thèse, constitué en trois parties, est consacrée à l'étudie des valeurs spéciales de fonctions L automorphes. La première partie contient un survol rapide de la théorie des formes modulaires et des fonctions L de puissance symétrique associées qui est nécessaire dans la suite. Dans la seconde partie, nous nous concentrons sur les valeurs centrales, par l'étude des moments intégraux dans petit intervalle, pour les fonctions L automorphes. On prouve la conjecture de Conrey et al. et donne l'ordre exact pour les moments sous l'hypothèse de Riemann généralisée. La troisième partie présente des travaux sur les valeurs en s=1 de la fonction L de puissance symétrique en l'aspect de niveau-poids. On généralise et/ou améliore les résultats sur l'encadrement de la fonction L de puissance symétrique, la conjecture de Montgomery-Vaughan et également la fonction de répartition. Une application des valeurs extrêmes sur la distribution des coefficients des formes primitives concernant la conjecture de Sato-Tate est donnée / Special values of automorphic L-functions are considered in this work in three parts. In the first part, elementary information about automorphic forms and associated symmetric power L-functions, which will be very useful in the following parts, is introduced. In the second part, we study the central values, in the form of higher moment in short interval, of automorphic L-functions and give a proof for the conjecture of Conrey et al. to get the sharp bound for the moment under Generalized Riemann Hypothesis. In the last part, values of automorphic L-functions at s=1 are considered in level-weight aspect. We generalize and/or improve related early results about the bounds of values at s=1, the Montgomery-Vaughan's conjecture and distribution functions. As an application of our results on extreme values, the distribution of coefficients of primitive forms concerning the Sato-Tate conjecture is studied