This dissertation is concerned with the zeros of holomorphic Hecke cusp forms in the space of newforms. We estimate a lower bound for the number of zeros on the imaginary axis and on the vertical line R(z)=1/2 in the upper half plane, both of which are outside the unit circle centered at the origin, and we denote these by δ1 and δ2 respectively. Ghosh and Sarnak call those zeros that lie on the rays 'real' including the arc z=exp (iθ), π/3 ≤ θ ≤ π/2, and they showed that a lower bound for the zeros on those geodesic lines is C log k for all sufficiently large weight k for the level 1 case. We extend their results to the newforms with levels N which are positive integers not divisible by 4 on δ2, and N which are positive integers on δ1. On δ2 we have C log k zeros if the weight k is sufficiently large and on δ1 we assume a nonnegativity result on the first negative Hecke eigenvalue and get a conditional result C log k zeros as the weight k goes to infinity. The analysis is closely related to the knowledge of Hecke eigenvalues λf (n). Most importantly it requires Deligne's bound λf (n) n^e (for every e > 0) with which we look into the proof of Theorem 3.1 in Ghosh and Sarnak cite[1], and get the same the approximation theorem for any level in Chapter 2. The estimation of zeros on δ1 also requires a `good' upper bound for the first negative Hecke eigenvalue for which we investigate an upper bound for central values of Hecke L-functions and a nonnegativity result on those values. Those will be studied in Chapters 3 and 4. In Chapter 5 we estimate lower bounds for the number of zeros on δi , i = 1, 2.

Submitted by Eloiza do Nascimento Fazinazzo null (elofazinazzo@hotmail.com) on 2016-09-12T20:02:28Z No. of bitstreams: 1 EloizaNFazinazzo_Dissertação.pdf: 2610907 bytes, checksum: 0d329afcf9d2ecddb98957de37f5ba97 (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-09-14T19:35:27Z (GMT) No. of bitstreams: 1 fazinazzo_en_me_prud.pdf: 2610907 bytes, checksum: 0d329afcf9d2ecddb98957de37f5ba97 (MD5) / Made available in DSpace on 2016-09-14T19:35:27Z (GMT). No. of bitstreams: 1 fazinazzo_en_me_prud.pdf: 2610907 bytes, checksum: 0d329afcf9d2ecddb98957de37f5ba97 (MD5) Previous issue date: 2016-07-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Neste trabalho foi realizado um estudo sobre o comportamento dos zeros de polinômios palindrômicos, com foco nos zeros reais. Condições necessárias e suficientes para que um polinômio palindrômico com coeficientes reais tenha somente zeros reais são estabelecidas. / In this work is presented a study of the behavior of the zeros of palindromic polynomials, focusing on real zeros. Necessary and sufficient conditions for a palindromic polynomial with real coefficients has only real zeros are established. / FAPESP: 2014/06785-2

Orientador: Eliana Xavier Linhares de Andrade / Banca: José Roberto Nogueira / Banca: Heloísa Helena Marino Silva / Resumo: O principal objetivo deste trabalho é realizar um estudo sobre polinômios algébricos e trigonométricos que possuem somente zeros reais. O Teorema de Hermite nos dá condições necessárias e su cientes para que isto aconteça. São discutidas questões relacionadas à localização dos zeros, onde a Regra de Sinais de Descartes teve grande importância. Além disso, alguns teoremas clássicos sobre zeros de polinômios algébricos e trigonométricos são apresentados. / Abstract: The main purpose of this work is to study algebraic and trigonometric poly- nomials that have only real zeros. The Hermite Theorem gives necessary and su cient conditions for this to be true. Questions concerning the locations of the zeros are discussed, where the Descarte's Rule of Signs is of great impor- tance. Furthermore, some classical theorems concerning zeros of algebraic and trigonometric polynomials are presented. / Mestre

This licentiate consists of two papers treating polynomial sequences defined by linear recurrences. In paper I, we establish necessary and sufficient conditions for the reality of all the zeros in a polynomial sequence {P_i} generated by a three-term recurrence relation P_i(x)+ Q_1(x)P_{i-1}(x) +Q_2(x) P_{i-2}(x)=0 with the standard initial conditions P_{0}(x)=1, P_{-1}(x)=0, where Q_1(x) and Q_2(x) are arbitrary real polynomials. In paper II, we study the root distribution of a sequence of polynomials {P_n(z)} with the rational generating function \sum_{n=0}^{\infty} P_n(z)t^n= \frac{1}{1+ B(z)t^\ell +A(z)t^k} for (k,\ell)=(3,2) and (4,3) where A(z) and B(z) are arbitrary polynomials in z with complex coefficients. We show that the roots of P_n(z) which satisfy A(z)B(z)\neq 0 lie on a real algebraic curve which we describe explicitly.

Indiana University-Purdue University Indianapolis (IUPUI) / We consider the behavior of zeros of random polynomials of the from \begin{equation*} P_{n,m}(z) := \eta_0\varphi_m^{(m)}(z) + \eta_1 \varphi_{m+1}^{(m)}(z) + \cdots + \eta_n \varphi_{n+m}^{(m)}(z) \end{equation*} as \( n\to\infty \), where \( m \) is a non-negative integer (most of the work deal with the case \( m =0 \) ), \( \{\eta_n\}_{n=0}^\infty \) is a sequence of i.i.d. Gaussian random variables, and \( \{\varphi_n(z)\}_{n=0}^\infty \) is a sequence of orthonormal polynomials on the unit circle \( \mathbb T \) for some Borel measure \( \mu \) on \( \mathbb T \) with infinitely many points in its support. Most of the work is done by manipulating the density function for the expected number of zeros of a random polynomial, which we call the intensity function.

Made available in DSpace on 2014-06-11T19:27:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2003-02-24Bitstream added on 2014-06-13T20:08:13Z : No. of bitstreams: 1 botta_va_me_sjrp.pdf: 571155 bytes, checksum: 6e200c838e03e019c93da99a37b1515f (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O principal objetivo deste trabalho é realizar um estudo sobre polinômios algébricos e trigonométricos que possuem somente zeros reais. O Teorema de Hermite nos dá condições necessárias e su cientes para que isto aconteça. São discutidas questões relacionadas à localização dos zeros, onde a Regra de Sinais de Descartes teve grande importância. Além disso, alguns teoremas clássicos sobre zeros de polinômios algébricos e trigonométricos são apresentados. / The main purpose of this work is to study algebraic and trigonometric poly- nomials that have only real zeros. The Hermite Theorem gives necessary and su cient conditions for this to be true. Questions concerning the locations of the zeros are discussed, where the Descarte's Rule of Signs is of great impor- tance. Furthermore, some classical theorems concerning zeros of algebraic and trigonometric polynomials are presented.

<div> <br></div><div> We consider the behavior of zeros of random polynomials of the from</div><div> \begin{equation*}</div><div> P_{n,m}(z) := \eta_0\varphi_m^{(m)}(z) + \eta_1 \varphi_{m+1}^{(m)}(z) + \cdots + \eta_n \varphi_{n+m}^{(m)}(z)</div><div> \end{equation*}</div><div> as \( n\to\infty \), where \( m \) is a non-negative integer (most of the work deal with the case \( m =0 \) ), \( \{\eta_n\}_{n=0}^\infty \) is a sequence of i.i.d. Gaussian random variables, and \( \{\varphi_n(z)\}_{n=0}^\infty \) is a sequence of orthonormal polynomials on the unit circle \( \mathbb T \) for some Borel measure \( \mu \) on \( \mathbb T \) with infinitely many points in its support. Most of the work is done by manipulating the density function for the expected number of zeros of a random polynomial, which we call the intensity function.</div>