Elasticity for integral-valued polynomials

AbstractThe elasticity of a domain is the upper bound of the ratios of lengths of two decompositions in irreducible factors of nonzero nonunit elements. We show that for a large class of Noetherian domains, including any domain contained in a number field (but not a field), the elasticity of the ring of integral-valued polynomials is infinite

Skolem properties, value-functions, and divisorial ideals

AbstractLet D be the ring of integers of a number field K. It is well known that the ring Int(D) = {f ϵ K[X] ¦ f (D) ⊆ D} of integer-valued polynomials on D is a Prüfer domain. Here we study the divisorial ideals of Int(D) and prove in particular that Int(D) has no divisorial prime ideal.We begin with the local case. We show that, if V is a rank-one discrete valuation domain with finite residue field, then the unitary ideals of Int(V) (that is, the ideals containing nonzero constants) are entirely determined by their values on the completion of V. This improves on the Skolem properties which only deal with finitely generated ideals. We then globalize and consider a Dedekind domain D with finite residue fields. We show that a prime ideal of t(D) is invertible if and only if it is divisorial, and also, in the case where the characteristic of D is 0, if and only if it is an upper to zero which is maximal

« Des images comme des oiseaux »

La notion d’« artistes iconographes », développée par Garance Chabert et Aurélien Mole dans leur catalogue éponyme publié en 2018, permet d’aborder la question du réemploi d’images, si ce n’est jugées patrimoniales, du moins préexistantes à l’activité artistique, dans le champ de l’art contemporain. Ces pratiques donnent une autre visibilité à l’objet photographique et s’attachent souvent à sa matérialité. Entre réflexe de sauvegarde et critique du processus institutionnel, l’usage matériel ..

Multi-Jet Event Rates in Deep Inelastic Scattering and Determination of the Strong Coupling Constant

Jet event rates in deep inelastic ep scattering at HERA are investigated applying the modified JADE jet algorithm. The analysis uses data taken with the H1 detector in 1994 and 1995. The data are corrected for detector and hadronization effects and then compared with perturbative QCD predictions using next-to-leading order calculations. The strong coupling constant alpha_S(M_Z^2) is determined evaluating the jet event rates. Values of alpha_S(Q^2) are extracted in four different bins of the negative squared momentum transfer~\qq in the range from 40 GeV2 to 4000 GeV2. A combined fit of the renormalization group equation to these several alpha_S(Q^2) values results in alpha_S(M_Z^2) = 0.117+-0.003(stat)+0.009-0.013(syst)+0.006(jet algorithm).Comment: 17 pages, 4 figures, 3 tables, this version to appear in Eur. Phys. J.; it replaces first posted hep-ex/9807019 which had incorrect figure 4

Measurement of Leading Proton and Neutron Production in Deep Inelastic Scattering at HERA

Deep--inelastic scattering events with a leading baryon have been detected by the H1 experiment at HERA using a forward proton spectrometer and a forward neutron calorimeter. Semi--inclusive cross sections have been measured in the kinematic region 2 <= Q^2 <= 50 GeV^2, 6.10^-5 <= x <= 6.10^-3 and baryon p_T <= MeV, for events with a final state proton with energy 580 <= E' <= 740 GeV, or a neutron with energy E' >= 160 GeV. The measurements are used to test production models and factorization hypotheses. A Regge model of leading baryon production which consists of pion, pomeron and secondary reggeon exchanges gives an acceptable description of both semi-inclusive cross sections in the region 0.7 <= E'/E_p <= 0.9, where E_p is the proton beam energy. The leading neutron data are used to estimate for the first time the structure function of the pion at small Bjorken--x.Comment: 30 pages, 9 figures, 2 tables, submitted to Eur. Phys.

Performance of the CMS Cathode Strip Chambers with Cosmic Rays

The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns

The role of thermal energy accommodation and atomic recombination probabilities in low pressure oxygen plasmas

International audienceSurface interaction probabilities are critical parameters that determine the behaviour of low pressure plasmas and so are crucial input parameters for plasma simulations that play a key role in determining their accuracy. However, these parameters are difficult to estimate without in situ measurements. In this work, the role of two prominent surface interaction probabilities, the atomic oxygen recombination coefficient ? O and the thermal energy accommodation coefficient ? E in determining the plasma properties of low pressure inductively coupled oxygen plasmas are investigated using two-dimensional fluid-kinetic simulations. These plasmas are the type used for semiconductor processing. It was found that ? E plays a crucial role in determining the neutral gas temperature and neutral gas density. Through this dependency, the value of ? E also determines a range of other plasma properties such as the atomic oxygen density, the plasma potential, the electron temperature, and ion bombardment energy and neutral-to-ion flux ratio at the wafer holder. The main role of ? O is in determining the atomic oxygen density and flux to the wafer holder along with the neutral-to-ion flux ratio. It was found that the plasma properties are most sensitive to each coefficient when the value of the coefficient is small causing the losses of atomic oxygen and thermal energy to be surface interaction limited rather than transport limited