8,377 research outputs found

    Light-Cone Gauge String Field Theory in Noncritical Dimensions

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    We study light-cone gauge string field theory in noncritical space-time dimensions. Such a theory corresponds to a string theory in a Lorentz noninvariant background. We identify the worldsheet theory for the longitudinal coordinate variables X±X^\pm and study its properties. It is a CFT with the right value of Virasoro central charge, using which we propose a BRST invariant formulation of the worldsheet theory.Comment: 27 pages, 2 figure

    Light-cone Gauge NSR Strings in Noncritical Dimensions

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    Light-cone gauge NSR string theory in noncritical dimensions should correspond to a string theory with a nonstandard longitudinal part. Supersymmetrizing the bosonic case [arXiv:0909.4675], we formulate a superconformal worldsheet theory for the longitudinal variables X^{\pm}, \psi^{\pm}. We show that with the transverse variables and the ghosts combined, it is possible to construct a nilpotent BRST charge.Comment: 22 pages, 1 figur

    Twist-3 Effects in Polarized Photon Structure

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    The polarized photon structure is described by two spin structure functions g1γg_1^\gamma and g2γg_2^\gamma which can be studied in the future polarized ep or e+^+e^- colliders. Here we investigate the QCD twist-3 effects in g2γg_2^\gamma to the leading order in QCD.Comment: 4 pages, LaTeX2e, 2 eps figures, ws-ijmpa.cls file included, Talk given at the 3rd Circum-Pan-Pacific Symposium on High Energy Spin Physics, Beijing, October 8-13, 2001, to appear in the Proceeding

    Light-cone Gauge Superstring Field Theory and Dimensional Regularization II

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    We propose a dimensional regularization scheme to deal with the divergences caused by colliding supercurrents inserted at the interaction points, in the light-cone gauge NSR superstring field theory. We formulate the theory in dd dimensions and define the amplitudes as analytic functions of dd. With an appropriately chosen three-string interaction term and large negative dd, the tree level amplitudes for the (NS,NS) closed strings can be recast into a BRST invariant form, using the superconformal field theory proposed in Ref.[arXiv:0911.3704]. We show that in the limit d10d \to 10 they coincide with the results of the first quantized theory. Therefore we obtain the desired results without adding any contact interaction terms to the action.Comment: 23 pages; v2: minor modifications; v3: revised argument in section 3, added appendix C, results unchanged; v4: added clarifications, two figures and a footnote; v5: minor modification

    Light-cone Gauge NSR Strings in Noncritical Dimensions II -- Ramond Sector

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    Light-cone gauge superstring theory in noncritical dimensions corresponds to a worldsheet theory with nonstandard longitudinal part in the conformal gauge. The longitudinal part of the worldsheet theory is a superconformal field theory called X^{\pm} CFT. We show that the X^{\pm} CFT combined with the super-reparametrization ghost system can be described by free variables. It is possible to express the correlation functions in terms of these free variables. Bosonizing the free variables, we construct the spin fields and BRST invariant vertex operators for the Ramond sector in the conformal gauge formulation. By using these vertex operators, we can rewrite the tree amplitudes of the noncritical light-cone gauge string field theory, with external lines in the (R,R) sector as well as those in the (NS,NS) sector, in a BRST invariant way.Comment: 33 pages; v2: minor modification

    Atomic layer deposition of HfO2 on graphene from HfCl4 and H20

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    Atomic layer deposition of ultrathin HfO2 on unmodified graphene from HfCl4 and H2O was investigated. Surface RMS roughness down to 0.5 nm was obtained for amorphous, 30 nm thick hafnia film grown at 180 degrees C. HfO2 was deposited also in a two-step temperature process where the initial growth of about 1 nm at 170 degrees C was continued up to 10-30 nm at 300 degrees C. This process yielded uniform, monoclinic HfO2 films with RMS roughness of 1.7 nm for 10-12 nm thick films and 2.5 nm for 30 nm thick films. Raman spectroscopy studies revealed that the deposition process caused compressive biaxial strain in graphene whereas no extra defects were generated. An 11 nm thick HfO2 film deposited onto bilayer graphene reduced the electron mobility by less than 10% at the Dirac point and by 30-40% far away from it.Comment: 4 figures, accepted by CEJ

    Influence of Mac Arthur Journal Donation Project on Serial Resources of Selected University Libraries in Nigeria

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    This study was carried out to assess the Mac Arthur Journal Donation Project in Selected University Libraries in Nigeria. Four research questions were posed in order to assess the Mac Arthur Journal Donation Project before, during and after the Donation. The research adopted survey method using questionnaire as instrument for data collection. Data collected were subjected to a descriptive analysis using frequency tables with graphical illustrations. The study discovered that the serial resources in these university libraries were inadequate before the intervention of Mac Arthur but improved substantially during and after the intervention. Consultation of serial resources was low before the intervention as majority of readers were dissatisfied with the serial resources that were available. The intervention brought an upward reversal in the resources and level of consultation. The study concluded that the intervention positively impacted on these university libraries through increased acquisition of current resources and their use. It recommended improved funding, training of staff, formation of consortia groups, library donations etc as measures to keep these university libraries alive
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