1,485 research outputs found

    Conference Summary of QNP2018

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    This report is the summary of the Eighth International Conference on Quarks and Nuclear Physics (QNP2018). Hadron and nuclear physics is the field to investigate high-density quantum many-body systems bound by strong interactions. It is intended to clarify matter generation of universe and properties of quark-hadron many-body systems. The QNP is an international conference which covers a wide range of hadron and nuclear physics, including quark and gluon structure of hadrons, hadron spectroscopy, hadron interactions and nuclear structure, hot and cold dense matter, and experimental facilities. First, I introduce the current status of the hadron and nuclear physics field related to this conference. Next, the organization of the conference is explained, and a brief overview of major recent developments is discussed by selecting topics from discussions at the plenary sessions. They include rapidly-developing field of gravitational waves and nuclear physics, hadron interactions and nuclear structure with strangeness, lattice QCD, hadron spectroscopy, nucleon structure, heavy-ion physics, hadrons in nuclear medium, and experimental facilities of EIC, GSI-FAIR, JLab, J-PARC, Super-KEKB, and others. Nuclear physics is at a fortunate time to push various projects at these facilities. However, we should note that the projects need to be developed together with related studies in other fields such as gravitational physics, astrophysics, condensed-matter physics, particle physics, and fundamental quantum physics.Comment: 10 pages, LaTeX, 1 style file, 3 figure files, Proceedings of Eighth International Conference on Quarks and Nuclear Physics (QNP2018), November 13-17, 2018, Tsukuba, Japa

    Measurement of the cross-section and forward-backward charge asymmetry for the b and c-quark in e+e- annihilation with inclusive muons at sqrt(s) = 58 GeV

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    We have studied inclusive muon events using all the data collected by the TOPAZ detector at sqrt(s)=58 GeV with an integrated luminosity of 273pb-1. From 1328 inclusive muon events, we measured the ratio R_qq of the cross section for qq-bar production to the total hadronic cross section and forward-backward asymmetry A^q_FB for b and c quarks. The obtained results are R_bb = 0.13+-0.02(stat)+-0.01(syst), R_cc = 0.36+-0.05(stat)+-0.05(syst), A^b_FB = -0.20+-0.16(stat)+-0.01(syst) and A^c_FB = -0.17+-0.14(stat)+-0.02(syst), in fair agreement with a prediction of the standard model.Comment: To be published in EPJ C. 24 pages, 12 figure

    Effects of radiation damage caused by proton irradiation on Multi-Pixel Photon Counters (MPPCs)

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    We have investigated the effects caused by proton-induced radiation damage on Multi-Pixel Photon Counter (MPPC), a pixelized photon detector developed by Hamamatsu Photonics. The leakage current of irradiated MPPC samples linearly increases with total irradiated doses due to radiation damage, which is not completely recovered even after a year from the irradiation. No significant change has been observed in the gains at least up to 8.0 Gy (9.1×1079.1\times10^7 n/mm2^2 in 1 MeV neutron equivalent fluence, Φeq\Phi_{\rm eq}). The device has completely lost its photon-counting capability due to baseline fluctuations and noise pile-up after 21 Gy irradiation (2.4×1082.4\times10^8 n/mm2^2 in Φeq\Phi_{\rm eq}), which might be problematic for some applications, such as ring-imaging Cherenkov detectors. We have found that the pulse-height resolution has been slightly deteriorated after 42 Gy irradiation (4.8×1084.8\times10^8 n/mm2^2 in Φeq\Phi_{\rm eq}), where the measured sample has been illuminated with a few hundred photons. This effect should be considered in the case of energy-measurement applications.Comment: 18 pages, 10 figure

    K0(K0ˉ)K^0(\bar{K^0}) Production in Two-Photon Processes at TRISTAN

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    We have carried out an inclusive measurement of K0(K0ˉ)K^0(\bar{K^0}) production in two-photon processes at TRISTAN. The mean s\sqrt{s} was 58 GeV and the integrated luminosity was 199 pb1^{-1}. High-statistics KsK_s samples were obtained under such conditions as no-, anti-electron, and remnant-jet tags. The remnant-jet tag, in particular, allowed us, for the first time, to measure the cross sections separately for the resolved-photon and direct processes.Comment: 20 pages, Latex format, 4 figures and KEK-mark included. Table 1 revised. To be published in Phys. Lett.

    Constraints on New Physics in the Electroweak Bosonic Sector from Current Data and Future Experiments

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    Extensions of the Standard Model which involve a new scale, Λ\Lambda, may, for energies sufficiently small compared to this new scale, be expressed in terms of operators with energy dimension greater than four. The coefficients of just four SU(2)×\timesU(1)-gauge-invariant energy-dimension-six operators are sufficient to parameterize the contributions of new physics in the electroweak bosonic sector to electroweak precision measurements. In this letter we update constraints on the coefficients of these four operators due to recent precision measurements of electroweak observables. We further demonstrate how such constraints may be improved by experiments at TRISTAN, LEP2 and at a future linear e+ee^+e^- collider. The relationship of these operators to the oblique parameters SS, TT and UU is examined. Two of the operators contribute to a non-standard running of the electroweak charge form-factors α(q2)\overline{\alpha}(q^2), s2(q2)\overline{s}^2(q^2), gZ2(q2)\overline{g}_Z^2(q^2) and gW2(q2)\overline{g}_W^2(q^2); in the special case where the coefficients of these two vanish the operator analysis reduces to an analysis in terms of SS, TT and UU with U=0U = 0.Comment: documentstyle[preprint,aps,floats,cite,psfig,subeqn]{revtex}, one figure compressed and encoded using uufiles, .ps version available via anonymous ftp from ftp://ftp.kek.jp/kek/preprints/TH/TH-44

    Averages of bb-hadron, cc-hadron, and τ\tau-lepton properties as of summer 2014

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    This article reports world averages of measurements of bb-hadron, cc-hadron, and τ\tau-lepton properties obtained by the Heavy Flavor Averaging Group (HFAG) using results available through summer 2014. For the averaging, common input parameters used in the various analyses are adjusted (rescaled) to common values, and known correlations are taken into account. The averages include branching fractions, lifetimes, neutral meson mixing parameters, CPCP violation parameters, parameters of semileptonic decays and CKM matrix elements.Comment: 436 pages, many figures and tables. Online updates available at http://www.slac.stanford.edu/xorg/hfag

    Measurement of the forward-backward asymmetries for charm- and bottom-quark pair productions at <s><\sqrt{s}>=58GeV with electron tagging

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    We have measured, with electron tagging, the forward-backward asymmetries of charm- and bottom-quark pair productions at =58.01GeV, based on 23,783 hadronic events selected from a data sample of 197pb1^{-1} taken with the TOPAZ detector at TRISTAN. The measured forward-backward asymmetries are AFBc=0.49±0.20(stat.)±0.08(sys.)A_{FB}^c = -0.49 \pm 0.20(stat.) \pm 0.08 (sys.) and AFBb=0.64±0.35(stat.)±0.13(sys.)A_{FB}^b = -0.64 \pm 0.35(stat.) \pm 0.13 (sys.), which are consistent with the standard model predictions.Comment: 19 pages, Latex format (article), 5 figures included. to be published in Phys. Lett.
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