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排序方式: 共有696条查询结果,搜索用时 93 毫秒
691.
We present the results of the search for supermassive magnetic monopoles with the MACRO experiment. Our detector is equipped with three independent subdetectors (liquid scintillation counters, limited streamer tubes and nuclear track detectors), operating in different ranges of monopole velocity. In several years of data taking no candidates were found; the present flux upper limits are the level of half the Parker Bound for β > 10−4; for 10−4 < β < 5 × 10−2 the limit is the best existing. 相似文献
692.
The CHORUS experiment is designed to search for νμ → ντ oscillation with a hybrid detector system containing 800 kg nuclear emulsions as target and vertex detector. Run I (320 000 recorded νμCC in 1994/5) and more than half of the run II (460 000 νμCC in 1996/7) data taking have been successfully completed. Approximately 80 000 events have been analyzed so far, searching for
and τ− → h− (nπ0) ντ decays. No candidate has been found, leading to a limit sin2 2θμτ ≤ 4.5 10−3 for large Δm2. 相似文献
693.
The NEMO-2 prototype, built for background measurements and located in the Fréjus Underground Laboratory (4800 m w.e.) has provided results with three ββ decay sources, 100Mo, 116Cd and 82Se with data accumulated over a total of 23000 h. Final results of ββ2ν half-lives measurements and limits on 0ν modes are given here. The NEMO-3 detector which will be able to accomodate sources of 10 kg is now under construction. The aim of the experiment is to reach a half-life measurement of 1025y for ββ0ν decay, which corresponds to a Majorana neutrino mass of 0.1 eV for 100Mo. 相似文献
694.
DELPHI Collaboration P. Abreu et al. 《The European Physical Journal C - Particles and Fields》1999,6(3):385-401
Data taken by DELPHI during the 1995 and 1996 LEP runs have been used to search for the supersymmetric partners of electron,
muon and tau leptons and of top and bottom quarks. The observations are in agreement with standard model predictions. Limits
are set on sfermion masses. Searches for long lived scalar leptons from low scale supersymmetry breaking models exclude stau
masses below 55 GeV/c at the 95% confidence level, irrespective of the gravitino mass.
Received: 13 July 1998 / Published online: 19 November 1998 相似文献
695.
BES Collaboration 《中国物理C(英文版)》1995,19(1):93-96
The hadronic decays ,and ωf2(1270) have been studied in a sample of 1.27 million produced.Measurements of their branching fractions are presented. While obeys the "14% rule" predicted by theory, →ωf2 (1270) is suppressed comparing with the corresponding decay. As a vector-tensor pair combination, the ωf2 mode is the first example of a non-vector-pseudoscalar decay of charmonium which violates the above mentioned rule. 相似文献
696.
BES Collaboration 《中国物理C(英文版)》1995,19(8):673-685
The cross sections of e+e-→hadrons,e+e-,μ+μ-have been measured in the vicinity of J/ψresonance at BES/BEPC.The fit of the observed cross sections gives the new results of J/ψ resonance parameters:the partial widths to hadrons,electrons and muous are Γh=74.1±8.1keV,Γe= 5.14±0.39keV and Γμ=5.13±0.52keV respectively;the total width Γ=84.4±8.9keV;the branching fractions Γh/Γ=(87.8±0.5)%,Γe/Γ=(6.09± 0.33)%,and Γμ/Γ=(6.08±0.33) %. 相似文献