Detlev W. Hoffmann

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The inclusive e+p single and double differential cross sections for neutral and charged current processes are measured with the H1 detector at HERA. The data were taken in 1999 and 2000 at a centre-of-mass energy of √ s = 319GeV and correspond to an integrated luminosity of 65.2 pb−1. The cross sections are measured in the range of four-momentum transfer(More)
We extend to characteristic 2 a theorem by the first author which states that if φ and ψ are anisotropic quadratic forms over a field F such that dimφ ≤ 2 < dimψ for some nonnegative integer n, then φ stays anisotropic over the function field F (ψ) of ψ. The case of singular forms is systematically included. We give applications to the characterization of(More)
We study Pfister neighbors and their characterization over fields of characteristic 2, where we include the case of singular forms. We give a somewhat simplified proof of a theorem of Fitzgerald which provides a criterion for when a nonsingular quadratic form q is similar to a Pfister form in terms of the hyperbolicity of this form over the function field(More)
Let F be a eld of characteristic 6= 2. In this paper we investigate quadratic forms ' over F which are anisotropic and of dimension 2 n , n 2, such that in the Witt ring WF they can be written in the form ' = where and are anisotropic nresp. m-fold P ster forms, 1 m < n. We call these forms twisted P ster forms. Forms of this type with m = n 1 are of great(More)
Let F be a field of characteristic different from 2 and φ a virtual Albert form over F , i.e. an anisotropic 6-dimensional quadratic form over F which is still anisotropic over the field F ( √ d± φ). We give a complete description of the quadratic forms ψ such that φ becomes isotropic over the function field F (ψ). This completes the series of works ([H6],(More)
The cross section for ep → e bb̄X in photoproduction is measured with the H1 detector at the ep-collider HERA. The decay channel bb̄ → eeX ′ is selected by identifying the semielectronic decays of the b-quarks. The total production cross section is measured in the kinematic range given by the photon virtuality Q2 ≤ 1GeV, the inelasticity 0.05 ≤ y ≤ 0.65 and(More)
Differential photoproduction cross sections are measured for events containing D mesons. The data were taken with the H1 detector at the ep collider HERA and correspond to an integrated luminosity of 51.1 pb−1. The kinematic region covers small photon virtualities Q2 < 0.01 GeV2 and photon-proton centre-of-mass energies of 171 < Wγ p < 256 GeV. The details(More)
Deep-inelastic ep scattering data taken with the H1 detector at HERA and corresponding to an integrated luminosity of 106 pb are used to study the differential distributions of event shape variables. These include thrust, jet broadening, jet mass and the C-parameter. The four-momentum transfer Q is taken to be the relevant energy scale and ranges between 14(More)
A manifold is a Poincaré duality space without singularities. McCrory obtained a homological criterion of a global nature for deciding if a polyhedral Poincaré duality space is a homology manifold, i.e. if the singularities are homologically inessential. A homeomorphism of manifolds is a degree 1 map without double points. In this paper combinatorially(More)
After a long hiatus, the pace of determination of the structures of ribosomal proteins has accelerated dramatically. We discuss here the structures of five ribosomal proteins from Bacillus stearothermophilus: S5, S17, L6, L9, and L14. These structures represent several new motifs. Each of these structures has revealed new insights, and we have developed(More)