David W. Farmer

  1. Testing the functional equations of a high-degree Euler product.

    Authors: David W. Farmer, Nathan C. Ryan, Ralf Schmidt
    Subjects: Number Theory
    Abstract

    We study the L-functions associated to Siegel modular forms (equivalently,
    automorphic representations of ${\rm GSp}(4,\mathbb{A}_{\mathbb{Q}})$) both
    theoretically and numerically. For the L-functions of degrees 10, 14, and 16 we
    perform representation theoretic calculations to cast the Langlands L-function
    in classical terms. We develop a precise notion of what it means to test a
    conjectured functional equation for an L-function, and we apply this to the
    degree 10 adjoint L-function associated to a Siegel modular form.

  2. Landau-Siegel zeros and zeros of the derivative of the Riemann zeta function.

    Authors: David W. Farmer, Haseo Ki
    Subjects: Number Theory
    Abstract

    We show that if the derivative of the Riemann zeta function has sufficiently
    many zeros close to the critical line, then the zeta function has many closely
    spaced zeros. This gives a condition on the zeros of the derivative of the zeta
    function which implies a lower bound of the class numbers of imaginary
    quadratic fields.

  3. Roots of the derivative of the Riemann zeta function and of characteristic polynomials.

    Authors: David W. Farmer, Eduardo Dueñez, Sara Froehlich, Chris Hughes, Francesco Mezzadri, Toan Phan
    Subjects: Number Theory
    Abstract

    We investigate the horizontal distribution of zeros of the derivative of the
    Riemann zeta function and compare this to the radial distribution of zeros of
    the derivative of the characteristic polynomial of a random unitary matrix.
    Both cases show a surprising bimodal distribution which has yet to be
    explained. We show by example that the bimodality is a general phenomenon. For
    the unitary matrix case we prove a conjecture of Mezzadri concerning the
    leading order behavior, and we show that the same follows from the random
    matrix conjectures for the zeros of the zeta function.

  4. Approximation by polynomials and Blaschke products having all zeros on a circle.

    Authors: David W. Farmer, Pamela Gorkin
    Subjects: Complex Variables
    Abstract

    We show that a nonvanishing analytic function on a domain in the unit disc
    can be approximated by (a scalar multiple of) a Blaschke product whose zeros
    lie on a prescribed circle enclosing the domain. We also give a new proof of
    the analogous classical result for polynomials. A connection is made to
    universality results for the Riemann zeta function.

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