363 research outputs found

    Measurement of inclusive D+-(s) photoproduction at HERA

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    The first measurement of inclusive D-s(+/-) photoproduction at HERA has been performed with the ZEUS detector for photon- proton centre-of-mass energies; 130 lt W lt 280 GeV The measured cross section for 3 lt p(perpendicular to)(Ds) lt 12 GeV and \eta(Ds)\ lt 1.5 is sigma(ep→DsX) = 3.79 +/- 0.59(stat.)(- 0.46)(+0.26)(syst.) +/- 0.94(br.) nb, where the last error arises from the uncertainty in the D-s(+/-) decay branching ratio. The measurements are compared with inclusive D*(+/-) photoproduction cross sections in the same kinematic region and with QCD calculations. The D-s(+/-) cross sections lie above a fixed-order next-to-leading order calculation and agree better with a tree-level O(alpha alpha(s)(3)) calculation that was tuned to describe the ZEUS D* (+/-) cross sections. The ratio of D-s(+/-) to D*(+/-) cross sections is 0.41 +/- 0.07(stat.)(- 0.05)(+0.03)(syst.) +/- 0.10 (br.). From this ratio, the strangeness-suppression factor in charm photoproduction, within the LUND string fragmentation model, has been calculated to be gamma(s)= 0.27 +/- 0.05 +/- 0.07(br.). The cross-section ratio and gamma(s) are in good agreement with those obtained in charm production in e(+)e(-) annihilation

    Measurement of D

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    The photoproduction of D∗± mesons has been measured with the ZEUS detector at HERA at three different ep centre-of-mass energies, √ s, of 318, 251 and 225 GeV. For each data set, D∗± mesons were required to have transverse momentum, p D∗ T , and pseudorapidity, η D∗ , in the ranges 1.9 < pD∗ T < 20 GeV and |η D∗ | < 1.6. The events were required to have a virtuality of the incoming photon, Q2 , of less than 1 GeV2 . The dependence on √ s was studied by normalising to the high-statistics measurement at √ s = 318 GeV. This led to the cancellation of a number of systematic effects both in data and theory. Predictions from next-to-leading-order QCD describe the √ s dependence of the data well

    Diffractive photoproduction of D*(+/-) (2010) at HERA

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    Diffractive photoproduction of D*±(2010) mesons was measured with the ZEUS detector at the ep collider HERA, using an integrated luminosity of 78.6 pb-1. The D* mesons were reconstructed in the kinematic range: transverse momentum pT(D*) > 1.9 GeV and pseudorapidity |η(D*)|<1.6, using the decay D*+→D0π+s followed by D0→K-π+(+c.c.). Diffractive events were identified by a large gap in pseudorapidity between the produced hadronic state and the outgoing proton. Cross sections are reported for photon-proton centre-of-mass energies in the range 130 < W < 300 GeV and for photon virtualities Q2 < 1 GeV2, in two ranges of the Pomeron fractional momentum xIP<0.035 and xIP<0.01. The relative contribution of diffractive events to the inclusive D*±(2010) photoproduction cross section is about 6%. The data are in agreement with perturbative QCD calculations based on various parameterisations of diffractive parton distribution functions. The results are consistent with diffractive QCD factorisation. © Springer-Verlag Berlin Heidelberg 2007

    Measurement of diffractive production of D*+-(2010) mesons in deep inelastic scattering at HERA

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    Diffractive production of D*+/-(2010) mesons in deep inelastic scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 44.3 pb(-1). Diffractive charm production is identified by the presence of a large rapidity gap in the final state of events in which a D*+/- (2010) meson is reconstructed in the decay channel D*+/- → (D-0 → K(-)pi(+))pi(s)(+) (+ charge conjugate). Differential cross sections when compared with theoretical predictions indicate the importance of gluons in such diffractive interactions

    Measurement of D*+- production in deep inelastic e+- p scattering at HERA

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    Inclusive production of D*± (2010) mesons in deep inelastic scattering has been measured with the ZEUS detector at DESY HERA using an integrated luminosity of 81.9 pb-1. The decay channel D*+ →D0π+ with D 0→K-π+ and corresponding antiparticle decay were used to identify D* mesons. Differential D* cross sections with 1.

    The Organization of Autodesk Revit Software Interaction with Applications for Structural Analysis

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    AbstractThe article deals with the export procedure of building construction parameters from Autodesk Revit to the program of structural analysis. At first, the procedure uses the C# plug-in, which extracts parameters of the construction elements from the Revit document and outputs them to a text file. The parameters can be physical (properties of materials), geometrical (size, coordinates, the cross-sectional shape) and other. Then, a special program-converter reads the file, generates a beam frame model and stores the information in a new format, which is compatible with the program of structural analysis earlier developed by the authors. This program allows to add both vertical or horizontal loads and moment to any of the beam frame nodes. The finite element method is used for structural analysis. The deformation schema is showed as the result of finite element analysis under the loads. The opportunity to get Microsoft Word document, which contains main characteristics of beam construction, is implemented

    Photoproduction of D*(+/-) mesons associated with a leading neutron

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    The photoproduction of D*(+/-)(2010) mesons associated with a leading neutron has been observed with the ZEUS detector in ep collisions at HERA using an integrated luminosity of 80 pb(-1). The neutron carries a large fraction, x(L) gt 0.2, of the incoming proton beam energy and is detected at very small production angles, theta(n) lt 0.8 mrad, an indication of peripheral scattering. The D* meson is centrally produced with pseudorapidity \eta\ lt 1.5, and has a transverse momentum p(T) gt 1.9 GeV, which is large compared to the average transverse momentum of the neutron of 0.22 GeV The ratio of neutron-tagged to inclusive D* production is 8.85 +/- 0.93(stat.)(- 0.61)(+0.48)(syst.)% in the photon-proton center-of-mass energy range 130 lt W lt 280 Gev The data suggest that the presence of a hard scale enhances the fraction of events with a leading neutron in the final state

    Measurement of D+ and Lambda(+)(c) production in deep inelastic scattering at HERA

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    Charm production in deep inelastic scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 120 pb&lt;sup&gt;−1&lt;/sup&gt;. The hadronic decay channels D&lt;sup&gt;+&lt;/sup&gt; → K&lt;sub&gt;S&lt;/sub&gt;&lt;sup&gt;0&lt;/sup&gt; π&lt;sup&gt;+&lt;/sup&gt;, Λ&lt;sub&gt;c&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt; → pK&lt;sub&gt;S&lt;/sub&gt;&lt;sup&gt;0&lt;/sup&gt; and Λ&lt;sub&gt;c&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt; → Λπ&lt;sup&gt;+&lt;/sup&gt;, and their charge conjugates, were reconstructed. The presence of a neutral strange hadron in the final state reduces the combinatorial background and extends the measured sensitivity into the low transverse momentum region. The kinematic range is 0 &#60; &lt;sub&gt;pT&lt;/sub&gt; (D&lt;sup&gt;+&lt;/sup&gt;, Λ&lt;sub&gt;c&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;) &#60; 10 GeV, |η(D&lt;sup&gt;+&lt;/sup&gt;, Λ&lt;sub&gt;c&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;)| &#60; 1.6, 1.5 &#60; Q&lt;sup&gt;2&lt;/sup&gt; &#60; 1000 GeV&lt;sup&gt;2&lt;/sup&gt; and 0.02 &#60; y &#60; 0.7. Inclusive and differential cross sections for the production of D&lt;sup&gt;+&lt;/sup&gt; mesons are compared to next-to-leading-order QCD predictions. The fraction of c quarks hadronising into Λ&lt;sub&gt;c&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt; baryons is extracted

    High-Q2 neutral current cross sections in e+ p deep inelastic scattering at √s = 318 GeV

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    Cross sections for e(+)p neutral current deep inelastic scattering have been measured at a center-of-mass energy of roots=318 GeV with the ZEUS detector at HERA using an integrated luminosity of 63.2 pb(-1). The double-differential cross section, d(2)sigma/dxdQ(2), is presented for 200 GeV2 lt Q(2) lt 30 000 GeV2 and for 0.005 lt x lt 0.65. The single- differential cross sections dsigma/dQ(2), dsigma/dx and dsigma/dy are presented for Q(2) gt 200 GeV2. The effect of Z- boson-exchange is seen in dsigma/dx measured for Q(2) gt 10 000 GeV2. The data presented here were combined with ZEUS e(+)p neutral current data taken at roots=300 GeV and the structure function F-2(em) was extracted. All results agree well with the predictions of the Standard Model
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