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[en] Detailed study of the structure in the rapidity plane allows to determine the amount of single and double diffraction within a cluster model. From semi-inclusive data on correlations the average number of particles due to decay of one cluster can be estimated
[en] The discovery at the VES facility (IHEP) of a resonance with mass M=1814±10 MeV and width Γ∼200 MeV, observed in the diffraction interaction of π- mesons with momentum pπ=37 GeV/c on carbon nuclei in the channels π-A→Aπ-ηη and π-A→Aπ-η'η was previously reported. The most probable values of the quantum numbers are JPC=2-+, and possible values are JPC=1++. The relative probabilities of the decays are given by R=BR(X(1814)→π-η'η)/BR(X(1814)→π-ηη)=0.3±0.1. In the η' channel a structure resembling the scalar G(1590) meson is observed in the ηη' mass spectrum. An object with such properties does not coincide with known mesons and is not in the standard q bar q classification of mesons. If X(1814) has the quantum numbers JPC=2-+, then it is possible to explain its observed properties by assuming that it is a hybrid state. For confirmation of the proposed scheme it is necessary to have more precision in the quantum numbers and a more detailed analysis of the channel X→ηηπ, in particular a separation of the contributions of the S and D waves in the ηη system. The most persuasive argument, however, would be the discovery of other candidates for hybrids belonging to the 2-+ series
[en] B-factories have been successfully operating for more than 8 years, providing an unprecedented data sample of e+e0 → hadrons events. The BABAR and Belle experiments have in fact already collected over 550 fb-1 and 800 fb-1 respectively at the Υ(4s) center-of-mass (CM) energy. At this energy, the cross-section for tau production is of the same order of the cross-section for b production: σ(b(bar b)) ∼ 1.1 nb ∼ σ(τ+τ-) ∼ 0.9 nb. For this reason, B-factories can now be considered also Tau-factories. A review of the most recent results on standard tau decays from the BABAR and Belle experiments is presented in this article.
[en] The development of a dynamical model for investigating the nucleon resonances using the reactions of meson production from π N, γ N, N(e,e'), and N(ν,l) reactions is reviewed. The results for the Δ (1232) state are summarized and discussed. The progress in investigating higher mass nucleon resonances is reported.
[en] We report a measurement of the proton-air cross-section for particle production at the center-of-mass energy per nucleon of 57 TeV. This is derived from the distribution of the depths of shower maxima observed with the Pierre Auger Observatory: systematic uncertainties are studied in detail.
[en] Particle production by a semitransparent mirror accelerating on trajectories which simulate the Hawking effect was recently discussed in 3. This author points out that some results in 1 are incorrect. We show here that, contrary to statements therein, the main results and conclusions of the last paper remain valid, only Eq. (41) there and some particular implication are not. The misunderstanding actually comes from comparing two very different parameter regions, and from the fact that, in our work, the word statistics was used in an unusual way related to the sign of the β-Bogoliubov coefficient, and not with its ordinary meaning, connected with the number of particles emitted per mode.