896 research outputs found

    Software evolution: case study, OPAL

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    Limits on Low Scale Gravity from e+eW+W,ZZe^+ e^- \to W^+ W^-, ZZ and γγ\gamma \gamma

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    It has been proposed recently that the scale of quantum gravity (``the string scale'') can be MSM_S \sim few TeV with n2n \geq 2 extra dimensions of size R<R \stackrel{<}{\sim} mm so that, at distances greater than RR, Newtonian gravity with MPl1018M_{Pl} \sim 10^{18} GeV is reproduced if MPl2RnMSn+2M_{Pl}^2 \sim R^n M_S^{n+2}. Exchange of virtual gravitons in this theory generates higher-dimensional operators involving SM fields, suppressed by powers of MSM_S. We discuss constraints on this scenario from the contribution of these operators to the processes e+eW+W,ZZ,γγe^+ e^- \to W^+ W^-, ZZ, \gamma \gamma. We find that LEP2 can place a limit MS1M_S \approx 1 TeV from e+eW+W,ZZ,γγe^+ e^- \to W^+ W^-, ZZ, \gamma \gamma.Comment: Replacing an earlier version. A discussion of using polarized electron beams and some minor comments have been adde

    Experimental Summary on Hadronic Decays: A TAU98 Review

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    Selected results on hadronic decays of the tau lepton from the TAU98 Workshop are reviewed. A comprehensive picture emerges for strange particle branching fractions, and exploration of resonant substructure of both strange and non-strange decays is seen to have matured substantially.Comment: 10 pages, postscript file also available through http://w4.lns.cornell.edu/public/CLN

    The photon structure function measurements from LEP

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    The present knowledge of the structure of the photon based on measurements of photon structure functions is discussed. This review covers QED structure functions and the hadronic structure function F_2^gamma.The present knowledge of the structure of the photon based on measurements of photon structure functions is discussed. This review covers QED structure functions and the hadronic structure function F_2^gamma

    Nucleus polarizability contribution to the hydrogen-deuterium isotope shift

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    The correction to the hydrogen-deuterium isotope shift due to the proton and deuteron polarizability is evaluated on the basis of modern experimental data on the structure functions of inelastic lepton-nucleus scattering. The numerical value of this contribution is equal 63\pm 12 Hz.Comment: 5 page

    Use of modern software technology in the redesign of the OPAL trigger software

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    The Transversity Function and Double Spin Azimuthal Asymmetry in Semi-Inclusive Pion Leptoproduction

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    We show that the transverse momentum dependent transversity function is proportional to the longitudinal polarization of a quark in a transversely polarized proton. This result suggests an alternative, convenient method for determining transversity, without knowing unusual fragmentation functions. The method consists of measuring the double spin azimuthal asymmetry in semi-inclusive pion leptoproduction by a transversely polarized proton target. The asymmetry, which is twist 3, is estimated to be more than 10% under the most favorable conditions. The experiment we suggest is feasible at facilities like DESY and CERN.Comment: extended version; to appear on Int. Jou. Mod. Phys.

    Signatures of HyperCharge Axions in Colliders

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    If in addition to the standard model fields, a new pseudoscalar field that couples to hypercharge topological number density, the hypercharge axion, exists, it can be produced in colliders in association with photons or Z bosons, and detected by looking for its decay into photons or Z's. For a range of masses below a TeV and coupling above a fraction of 1/TeV, existing data from LEP II and the Tevatron can already put interesting constraints, and in future colliders accessible detection range is increased significantly. The hypercharge axion can help in explaining the matter-antimatter asymmetry in the universe.Comment: 11 pages, 8 figures, uses axodraw.st
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