295 research outputs found

    Exclusive ppnnπ+π+pp \to nn \pi^{+}\pi^{+} reaction at LHC and RHIC

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    We evaluate differential distributions for the four-body ppnnπ+π+p p \to n n \pi^+ \pi^+ reaction. The amplitude for the process is calculated in the Regge approach including many diagrams. We make predictions for possible future experiments at RHIC and LHC energies. Very large cross sections are found which is partially due to interference of a few mechanisms. Presence of several interfering mechanisms precludes extraction of the elastic π+π+\pi^+ \pi^+ scattering cross section. Absorption effects are estimated. Differential distributions in pseudorapidity, rapidity, invariant two-pion mass, transverse-momentum and energy distributions of neutrons are presented for proton-proton collisions at s\sqrt{s} = 500 GeV (RHIC) and s\sqrt{s} = 0.9, 2.36 and 7 TeV (LHC). Cross sections with experimental cuts are presented.Comment: 22 pages, 18 figures, calculations have been corrected, new processes added, discussion expanded in print in Phys. Rev.

    Recovery of the electric strength in a cold cathode thyratron

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    The paper deals with the investigations of the recovery process of electric strength in a cold cathode thyratron. Method which allows extracting the plasma of the preceding discharge not only from the cathode cavity but also from the main gap of the thyratron is proposed. Method is based on the usage of a low-current nonsteady state discharge in the pause between the pulses

    Experimental study of direct photon emission in K- --> pi- pi0 gamma decay using ISTRA+ detector

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    The branching ratio in the charged-pion kinetic energy region of 55 to 90 MeV for the direct photon emission in the K- --> pi- pi0 gamma decay has been measured using in-flight decays detected with the ISTRA+ setup operating in the 25 GeV/c negative secondary beam of the U-70 PS. The value Br(DE)=[0.37+-0.39(stat)+-0.10(syst)]*10^(-5) obtained from the analysis of 930 completely reconstructed events is consistent with the average value of two stopped-kaon experiments, but it differs by 2.5 standard deviations from the average value of three in-flight-kaon experiments. The result is also compared with recent theoretical predictions.Comment: 13 pages, 8 figure

    МАГНИТОЖИДКОСТНЫЕ ПОДШИПНИКИ ГОРНОДОБЫВАЮЩЕГО ОБОРУДОВАНИЯ

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    The paper considers a problem pertaining to selection friction pair materials for plain bearings of mining equipment which are lubricated with  nano-dispersed magnetic oil. Methodology for equipment tests, technology for obtaining new anti-friction materials (polymer, ceramic, amorphous) and investigation results are presented in the paper.Рассматривается вопрос рационального выбора материалов пар трения для подшипников скольжения горнодобывающего оборудования, смазываемых нанодисперсным магнитным маслом. Приведены методики испытаний, оборудование, технологии получения новых антифрикционных материалов (полимерных, керамических, аморфных) и полученные результаты

    Experimental Study of the Radiative Decays K+ -> mu+ nu e+e- and K+ -> e+ nu e+e-

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    Experiment 865 at the Brookhaven AGS obtained 410 K+ -> e+ nu e+e- and 2679 K+ -> mu+ nu e+e- events including 10% and 19% background. The branching ratios were measured to be (2.48+-0.14(stat.)+-0.14(syst.))x10^-8 (m_ee>150 MeV) and (7.06+-0.16+-0.26)x10^-8 (m_ee>145 MeV), respectively. Results for the decay form factors are presented.Comment: 4 pages, 3 figures, RevTeX

    Aspects of radiative K^+_e3 decays

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    We re-investigate the radiative charged kaon decay K+- --> pi0 e+- nu_e gamma in chiral perturbation theory, merging the chiral expansion with Low's theorem. We thoroughly analyze the precision of the predicted branching ratio relative to the non-radiative decay channel. Structure dependent terms and their impact on differential decay distributions are investigated in detail, and the possibility to see effects of the chiral anomaly in this decay channel is emphasized.Comment: 15 pages, 6 figure

    Neutral Particles in Light of the Majorana-Ahluwalia Ideas

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    The first part of this article (Sections I and II) presents oneself an overview of theory and phenomenology of truly neutral particles based on the papers of Majorana, Racah, Furry, McLennan and Case. The recent development of the construct, undertaken by Ahluwalia [{\it Mod. Phys. Lett. A}{\bf 9} (1994) 439; {\it Acta Phys. Polon. B}{\bf 25} (1994) 1267; Preprints LANL LA-UR-94-1252, LA-UR-94-3118], could be relevant for explanation of the present experimental situation in neutrino physics and astrophysics. In Section III the new fundamental wave equations for self/anti-self conjugate type-II spinors, proposed by Ahluwalia, are re-casted to covariant form. The connection with the Foldy-Nigam-Bargmann-Wightman- Wigner (FNBWW) type quantum field theory is found. The possible applications to the problem of neutrino oscillations are discussed.Comment: REVTEX file. 21pp. No figure

    ChPT tests at the NA48 and NA62 experiments at CERN

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    The NA48/2 Collaboration at CERN has accumulated unprecedented statistics of rare kaon decays in the Ke4 modes: Ke4(+-) (K±π+πe±νK^\pm \to \pi^+ \pi^- e^\pm \nu) and Ke4(00) (K±π0π0e±νK^\pm \to \pi^0 \pi^0 e^\pm \nu) with nearly one percent background contamination. The detailed study of form factors and branching rates, based on these data, has been completed recently. The results brings new inputs to low energy strong interactions description and tests of Chiral Perturbation Theory (ChPT) and lattice QCD calculations. In particular, new data support the ChPT prediction for a cusp in the π0π0\pi^0\pi^0 invariant mass spectrum at the two charged pions threshold for Ke4(00) decay. New final results from an analysis of about 400 K±π±γγK^\pm \to \pi^\pm \gamma \gamma rare decay candidates collected by the NA48/2 and NA62 experiments at CERN during low intensity runs with minimum bias trigger configurations are presented. The results include a model-independent decay rate measurement and fits to ChPT description.Comment: XIIth International Conference on Heavy Quarks and Leptons 2014, Mainz, German
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