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Identities Between Hecke Eigenforms Have Been Studied by Many Authors
Identities between Hecke Eigenforms D. Bao February 20, 2018 Abstract In this paper, we study solutions to h = af 2 + bfg + g2, where f,g,h are Hecke newforms with respect to Γ1(N) of weight k > 2 and a, b = 0. We show that the number of solutions is finite for 6 all N. Assuming Maeda’s conjecture, we prove that the Petersson inner product f 2, g is nonzero, where f and g are any nonzero cusp h i eigenforms for SL2(Z) of weight k and 2k, respectively. As a corollary, we obtain that, assuming Maeda’s conjecture, identities between cusp 2 n eigenforms for SL2(Z) of the form X + i=1 αiYi = 0 all are forced by dimension considerations. We also give a proof using polynomial P identities between eigenforms that the j-function is algebraic on zeros of Eisenstein series of weight 12k. 1 Introduction arXiv:1701.03189v1 [math.NT] 11 Jan 2017 Fourier coefficients of Hecke eigenforms often encode important arithmetic information. Given an identity between eigenforms, one obtains nontrivial relations between their Fourier coefficients and may in further obtain solu- tions to certain related problems in number theory. For instance, let τ(n) be the nth Fourier coefficient of the weight 12 cusp form ∆ for SL2(Z) given by ∞ ∞ ∆= q (1 qn)24 = τ(n)qn − n=1 n=1 Y X 1 11 and define the weight 11 divisor sum function σ11(n) = d n d . Then the Ramanujan congruence | P τ(n) σ (n) mod691 ≡ 11 can be deduced easily from the identity 1008 756 E E2 = × ∆, 12 − 6 691 where E6 (respectively E12) is the Eisenstein series of weight 6 (respectively 12) for SL2(Z). -
Automorphic L-Functions
Proceedings of Symposia in Pure Mathematics Vol. 33 (1979), part 2, pp. 27-61 AUTOMORPHIC L-FUNCTIONS A. BOREL This paper is mainly devoted to the L-functions attached by Langlands [35] to an irreducible admissible automorphic representation re of a reductive group G over a global field k and to local and global problems pertaining to them. In the context of this Institute, it is meant to be complementary to various seminars, in particular to the GL2-seminars, and to stress the general case. We shall therefore start directly with the latter, and refer for background and motivation to other seminars, or to some expository articles on this topic in general [3] or on some aspects of it [7], [14], [15], [23]. The representation re is a tensor product re = @,re, over the places of k, where re, is an irreducible admissible representation of G(k,) [11]. Accordingly the L-func tions associated to re will be Euler products of local factors associated to the 7r:.'s. The definition of those uses the notion of the L-group LG of, or associated to, G. This is the subject matter of Chapter I, whose presentation has been much influ enced by a letter of Deligne to the author. The L-function will then be an Euler product L(s, re, r) assigned to re and to a finite dimensional representation r of LG. (If G = GL"' then the L-group is essentially GLn(C), and we may tacitly take for r the standard representation r n of GLn(C), so that the discussion of GLn can be carried out without any explicit mention of the L-group, as is done in the first six sections of [3].) The local L- ands-factors are defined at all places where G and 1T: are "unramified" in a suitable sense, a condition which excludes at most finitely many places. -
On Moments of Twisted L-Functions
ARIZONA WINTER SCHOOL 2016: ANALYTIC THEORY OF TRACE FUNCTIONS PHILIPPE MICHEL, EPF LAUSANNE 1. Functions on congruence rings As was emphasized by C.F. Gauss in the Disquisitiones Arithmeticae (and probably much earlier), the concept of congruences (a.k.a arithmetic progressions of some modulus q, a.k.a the ring Z=qZ) is central in number theory. It is therefore fundamental to understand spaces of functions over the ring Z=qZ. One of the first classes of such functions to have been studied systematically (and one of the most interesting even today) is the group of Dirichlet's characters of modulus q, (Z\=qZ)×, the group homomorphisms χ :(Z=qZ)× ! C×: Indeed these functions enter crucially in Dirichlet's proof that there are infinitely many primes in any admissible arithmetic progression of modulus q [7]. The studying of integral solutions of diophantine equations is another important source of func- tions on congruence rings: these arise as a manifestation of some general local-global principles or more directly when using the circle method. For instance, while investigating the set of representa- tions of an integer d by some integral, positive, definite, quadratic form in four variables q(x; y; z; t), ie. the integral solutions to the equation (1.1) d = q(x; y; z; t); x; y; z; t 2 Z; Kloosterman came up with the very important function modulo q, the so-called "Kloosterman sums", 1 X m (mod q) 7! Kl (m; q) := p e (mx + y); 2 q q xy=1 (mod q) where eq(·) denote the additive character of (Z=qZ; +) 2πix e (x) := exp( ): q q By evaluating the fourth moment of this function over Z=qZ, Kloosterman established the following non-trivial bound 2=3−1=2+o(1) (1.2) Kl2(m; q) q and deduced from it an asymptotic formula for the number of solutions to the equations (1.1). -
Automorphic Forms for Some Even Unimodular Lattices
AUTOMORPHIC FORMS FOR SOME EVEN UNIMODULAR LATTICES NEIL DUMMIGAN AND DAN FRETWELL Abstract. We lookp at genera of even unimodular lattices of rank 12p over the ring of integers of Q( 5) and of rank 8 over the ring of integers of Q( 3), us- ing Kneser neighbours to diagonalise spaces of scalar-valued algebraic modular forms. We conjecture most of the global Arthur parameters, and prove several of them using theta series, in the manner of Ikeda and Yamana. We find in- stances of congruences for non-parallel weight Hilbert modular forms. Turning to the genus of Hermitian lattices of rank 12 over the Eisenstein integers, even and unimodular over Z, we prove a conjecture of Hentschel, Krieg and Nebe, identifying a certain linear combination of theta series as an Hermitian Ikeda lift, and we prove that another is an Hermitian Miyawaki lift. 1. Introduction Nebe and Venkov [54] looked at formal linear combinations of the 24 Niemeier lattices, which represent classes in the genus of even, unimodular, Euclidean lattices of rank 24. They found a set of 24 eigenvectors for the action of an adjacency oper- ator for Kneser 2-neighbours, with distinct integer eigenvalues. This is equivalent to computing a set of Hecke eigenforms in a space of scalar-valued modular forms for a definite orthogonal group O24. They conjectured the degrees gi in which the (gi) Siegel theta series Θ (vi) of these eigenvectors are first non-vanishing, and proved them in 22 out of the 24 cases. (gi) Ikeda [37, §7] identified Θ (vi) in terms of Ikeda lifts and Miyawaki lifts, in 20 out of the 24 cases, exploiting his integral construction of Miyawaki lifts. -
Modular Forms, the Ramanujan Conjecture and the Jacquet-Langlands Correspondence
Appendix: Modular forms, the Ramanujan conjecture and the Jacquet-Langlands correspondence Jonathan D. Rogawski1) The theory developed in Chapter 7 relies on a fundamental result (Theorem 7 .1.1) asserting that the space L2(f\50(3) x PGLz(Op)) decomposes as a direct sum of tempered, irreducible representations (see definition below). Here 50(3) is the compact Lie group of 3 x 3 orthogonal matrices of determinant one, and r is a discrete group defined by a definite quaternion algebra D over 0 which is split at p. The embedding of r in 50(3) X PGLz(Op) is defined by identifying 50(3) and PGLz(Op) with the groups of real and p-adic points of the projective group D*/0*. Although this temperedness result can be viewed as a combinatorial state ment about the action of the Heckeoperators on the Bruhat-Tits tree associated to PGLz(Op). it is not possible at present to prove it directly. Instead, it is deduced as a corollary of two other results. The first is the Ramanujan-Petersson conjec ture for holomorphic modular forms, proved by P. Deligne [D]. The second is the Jacquet-Langlands correspondence for cuspidal representations of GL(2) and multiplicative groups of quaternion algebras [JL]. The proofs of these two results involve essentially disjoint sets of techniques. Deligne's theorem is proved using the Riemann hypothesis for varieties over finite fields (also proved by Deligne) and thus relies on characteristic p algebraic geometry. By contrast, the Jacquet Langlands Theorem is analytic in nature. The main tool in its proof is the Seiberg trace formula. -
Scientific Report for 2013
Scientific Report for 2013 Impressum: Eigent¨umer,Verleger, Herausgeber: The Erwin Schr¨odingerInternational Institute for Mathematical Physics - U of Vienna (DVR 0065528), Boltzmanngasse 9, A-1090 Vienna. Redaktion: Goulnara Arzhantseva, Joachim Schwermer. Supported by the Austrian Federal Min- istry of Science and Research (BMWF) through the U of Vienna. Contents Preface 3 The Institute and its Mission in 2013 . 3 Scientific activities in 2013 . 4 The ESI in 2013 . 6 Scientific Reports 7 Main Research Programmes . 7 Teichm¨ullerTheory . 7 The Geometry of Topological D-branes, Categories, and Applications . 11 Jets and Quantum Fields for LHC and Future Colliders . 18 GEOQUANT 2013 . 25 Forcing, Large Cardinals and Descriptive Set Theory . 28 Heights in Diophantine Geometry, Group Theory and Additive Combinatorics . 31 Workshops organized independently of the Main Programmes . 36 ESI Anniversary - Two Decades at the Interface of Mathematics and Physics The [Un]reasonable Effectiveness of Mathematics in the Natural Sciences . 36 Word maps and stability of representations . 38 Complexity and dimension theory of skew products systems . 42 Advances in the theory of automorphic forms and their L-functions . 44 Research in Teams . 51 Marcella Hanzer and Goran Muic: Eisenstein Series . 51 Vladimir N. Remeslennikov et al: On the first-order theories of free pro-p groups, group extensions and free product groups . 53 Raimar Wulkenhaar et al: Exactly solvable quantum field theory in four dimensions . 57 Jan Spakula et al: Nuclear dimension and coarse geometry . 60 Alan Carey et al: Non-commutative geometry and spectral invariants . 62 Senior Research Fellows Programme . 64 Vladimir Korepin: The Algebraic Bethe Ansatz . 64 Simon Scott: Logarithmic TQFT, torsion, and trace invariants . -
Introduction to L-Functions II: Automorphic L-Functions
Introduction to L-functions II: Automorphic L-functions References: - D. Bump, Automorphic Forms and Repre- sentations. - J. Cogdell, Notes on L-functions for GL(n) - S. Gelbart and F. Shahidi, Analytic Prop- erties of Automorphic L-functions. 1 First lecture: Tate’s thesis, which develop the theory of L- functions for Hecke characters (automorphic forms of GL(1)). These are degree 1 L-functions, and Tate’s thesis gives an elegant proof that they are “nice”. Today: Higher degree L-functions, which are associated to automorphic forms of GL(n) for general n. Goals: (i) Define the L-function L(s, π) associated to an automorphic representation π. (ii) Discuss ways of showing that L(s, π) is “nice”, following the praradigm of Tate’s the- sis. 2 The group G = GL(n) over F F = number field. Some subgroups of G: ∼ (i) Z = Gm = the center of G; (ii) B = Borel subgroup of upper triangular matrices = T · U; (iii) T = maximal torus of of diagonal elements ∼ n = (Gm) ; (iv) U = unipotent radical of B = upper trian- gular unipotent matrices; (v) For each finite v, Kv = GLn(Ov) = maximal compact subgroup. 3 Automorphic Forms on G An automorphic form on G is a function f : G(F )\G(A) −→ C satisfying some smoothness and finiteness con- ditions. The space of such functions is denoted by A(G). The group G(A) acts on A(G) by right trans- lation: (g · f)(h)= f(hg). An irreducible subquotient π of A(G) is an au- tomorphic representation. 4 Cusp Forms Let P = M ·N be any parabolic subgroup of G. -
On Some Variants of the Gauss Circle Problem” by David Lowry-Duda, Ph.D., Brown University, May 2017
On Some Variants of the Gauss Circle Problem by David Lowry-Duda B.S. in Applied Mathematics, Georgia Institute of Technology, Atlanta, GA, 2011 B.S. in International Affairs and Modern Languages, Georgia Institute of Technology, Atlanta, GA, 2011 M.Sc. in Mathematics, Brown University, Providence, RI, 2015 A dissertation submitted in partial fulfillment of the arXiv:1704.02376v2 [math.NT] 2 May 2017 requirements for the degree of Doctor of Philosophy in the Department of Mathematics at Brown University PROVIDENCE, RHODE ISLAND May 2017 c Copyright 2017 by David Lowry-Duda Abstract of “On Some Variants of the Gauss Circle Problem” by David Lowry-Duda, Ph.D., Brown University, May 2017 The Gauss Circle Problem concerns finding asymptotics for the number of lattice point lying inside a circle in terms of the radius of the circle. The heuristic that the number of points is very nearly the area of the circle is surprisingly accurate. This seemingly simple problem has prompted new ideas in many areas of number theory and mathematics, and it is now recognized as one instance of a general phenomenon. In this work, we describe two variants of the Gauss Circle problem that exhibit similar characteristics. The first variant concerns sums of Fourier coefficients of GL(2) cusp forms. These sums behave very similarly to the error term in the Gauss Circle problem. Normalized correctly, it is conjectured that the two satisfy essentially the same asymptotics. We introduce new Dirichlet series with coefficients that are squares of partial sums of Fourier coefficients of cusp forms. We study the meromorphic properties of these Dirichlet series and use these series to give new perspectives on the mean square of the size of sums of these Fourier coefficients. -
Congruences Between Modular Forms
CONGRUENCES BETWEEN MODULAR FORMS FRANK CALEGARI Contents 1. Basics 1 1.1. Introduction 1 1.2. What is a modular form? 4 1.3. The q-expansion priniciple 14 1.4. Hecke operators 14 1.5. The Frobenius morphism 18 1.6. The Hasse invariant 18 1.7. The Cartier operator on curves 19 1.8. Lifting the Hasse invariant 20 2. p-adic modular forms 20 2.1. p-adic modular forms: The Serre approach 20 2.2. The ordinary projection 24 2.3. Why p-adic modular forms are not good enough 25 3. The canonical subgroup 26 3.1. Canonical subgroups for general p 28 3.2. The curves Xrig[r] 29 3.3. The reason everything works 31 3.4. Overconvergent p-adic modular forms 33 3.5. Compact operators and spectral expansions 33 3.6. Classical Forms 35 3.7. The characteristic power series 36 3.8. The Spectral conjecture 36 3.9. The invariant pairing 38 3.10. A special case of the spectral conjecture 39 3.11. Some heuristics 40 4. Examples 41 4.1. An example: N = 1 and p = 2; the Watson approach 41 4.2. An example: N = 1 and p = 2; the Coleman approach 42 4.3. An example: the coefficients of c(n) modulo powers of p 43 4.4. An example: convergence slower than O(pn) 44 4.5. Forms of half integral weight 45 4.6. An example: congruences for p(n) modulo powers of p 45 4.7. An example: congruences for the partition function modulo powers of 5 47 4.8. -
25 Modular Forms and L-Series
18.783 Elliptic Curves Spring 2015 Lecture #25 05/12/2015 25 Modular forms and L-series As we will show in the next lecture, Fermat's Last Theorem is a direct consequence of the following theorem [11, 12]. Theorem 25.1 (Taylor-Wiles). Every semistable elliptic curve E=Q is modular. In fact, as a result of subsequent work [3], we now have the stronger result, proving what was previously known as the modularity conjecture (or Taniyama-Shimura-Weil conjecture). Theorem 25.2 (Breuil-Conrad-Diamond-Taylor). Every elliptic curve E=Q is modular. Our goal in this lecture is to explain what it means for an elliptic curve over Q to be modular (we will also define the term semistable). This requires us to delve briefly into the theory of modular forms. Our goal in doing so is simply to understand the definitions and the terminology; we will omit all but the most straight-forward proofs. 25.1 Modular forms Definition 25.3. A holomorphic function f : H ! C is a weak modular form of weight k for a congruence subgroup Γ if f(γτ) = (cτ + d)kf(τ) a b for all γ = c d 2 Γ. The j-function j(τ) is a weak modular form of weight 0 for SL2(Z), and j(Nτ) is a weak modular form of weight 0 for Γ0(N). For an example of a weak modular form of positive weight, recall the Eisenstein series X0 1 X0 1 G (τ) := G ([1; τ]) := = ; k k !k (m + nτ)k !2[1,τ] m;n2Z 1 which, for k ≥ 3, is a weak modular form of weight k for SL2(Z). -
Automorphic Forms on Os+2,2(R)+ and Generalized Kac
+ Automorphic forms on Os+2,2(R) and generalized Kac-Moody algebras. Proceedings of the International Congress of Mathematicians, Vol. 1, 2 (Z¨urich, 1994), 744–752, Birkh¨auser,Basel, 1995. Richard E. Borcherds * Department of Mathematics, University of California at Berkeley, CA 94720-3840, USA. e-mail: [email protected] We discuss how modular forms and automorphic forms can be written as infinite products, and how some of these infinite products appear in the theory of generalized Kac-Moody algebras. This paper is based on my talk at the ICM, and is an exposition of [B5]. 1. Product formulas for modular forms. We will start off by listing some apparently random and unrelated facts about modular forms, which will begin to make sense in a page or two. A modular form of level 1 and weight k is a holomorphic function f on the upper half plane {τ ∈ C|=(τ) > 0} such that f((aτ + b)/(cτ + d)) = (cτ + d)kf(τ) ab for cd ∈ SL2(Z) that is “holomorphic at the cusps”. Recall that the ring of modular forms of level 1 is P n P n generated by E4(τ) = 1+240 n>0 σ3(n)q of weight 4 and E6(τ) = 1−504 n>0 σ5(n)q of weight 6, where 2πiτ P k 3 2 q = e and σk(n) = d|n d . There is a well known product formula for ∆(τ) = (E4(τ) − E6(τ) )/1728 Y ∆(τ) = q (1 − qn)24 n>0 due to Jacobi. This suggests that we could try to write other modular forms, for example E4 or E6, as infinite products. -
Algebra & Number Theory Vol. 4 (2010), No. 6
Algebra & Number Theory Volume 4 2010 No. 6 mathematical sciences publishers Algebra & Number Theory www.jant.org EDITORS MANAGING EDITOR EDITORIAL BOARD CHAIR Bjorn Poonen David Eisenbud Massachusetts Institute of Technology University of California Cambridge, USA Berkeley, USA BOARD OF EDITORS Georgia Benkart University of Wisconsin, Madison, USA Susan Montgomery University of Southern California, USA Dave Benson University of Aberdeen, Scotland Shigefumi Mori RIMS, Kyoto University, Japan Richard E. Borcherds University of California, Berkeley, USA Andrei Okounkov Princeton University, USA John H. Coates University of Cambridge, UK Raman Parimala Emory University, USA J-L. Colliot-Thel´ ene` CNRS, Universite´ Paris-Sud, France Victor Reiner University of Minnesota, USA Brian D. Conrad University of Michigan, USA Karl Rubin University of California, Irvine, USA Hel´ ene` Esnault Universitat¨ Duisburg-Essen, Germany Peter Sarnak Princeton University, USA Hubert Flenner Ruhr-Universitat,¨ Germany Michael Singer North Carolina State University, USA Edward Frenkel University of California, Berkeley, USA Ronald Solomon Ohio State University, USA Andrew Granville Universite´ de Montreal,´ Canada Vasudevan Srinivas Tata Inst. of Fund. Research, India Joseph Gubeladze San Francisco State University, USA J. Toby Stafford University of Michigan, USA Ehud Hrushovski Hebrew University, Israel Bernd Sturmfels University of California, Berkeley, USA Craig Huneke University of Kansas, USA Richard Taylor Harvard University, USA Mikhail Kapranov Yale