排序方式: 共有55条查询结果,搜索用时 156 毫秒
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Toyoda H Trischuk W de Troconiz JF Truitt S Tseng J Turini N Ukegawa F Valls J Vejcik S Velev G Vidal R Vilar R Vologouev I Vucinic D Wagner RG Wagner RL Wahl J Wallace NB Walsh AM Wang C Wang CH Wang MJ Watanabe T Waters D Watts T Webb R 《Physical review letters》2000,84(10):2094-2099
We have reconstructed the radiative decays chi(b)(1P)-->Upsilon(1S)gamma and chi(b)(2P)-->Upsilon(1S)gamma in p&pmacr; collisions at sqrt[s] = 1.8 TeV, and measured the fraction of Upsilon(1S) mesons that originate from these decays. For Upsilon(1S) mesons with p(Upsilon)(T)>8.0 GeV/c, the fractions that come from chi(b)(1P) and chi(b)(2P) decays are [27.1+/-6.9(stat)+/-4. 4(syst)]% and [10.5+/-4.4(stat)+/-1.4(syst)]%, respectively. We have derived the fraction of directly produced Upsilon(1S) mesons to be [50.9+/-8.2(stat)+/-9.0(syst)]%. 相似文献
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Poolman HR Boersma DJ Harvey M Higinbotham DW Passchier I Six E Alarcon R van Amersfoort PW Bauer TS Boer Rookhuizen H van Den Brand JF van Buuren LD Bulten HJ Ent R Ferro-Luzzi M Geurts DG Heimberg P de Jager CW Klimin P Koop I Kroes F van Der Laan J Luijckx G Lysenko A Militsyn B Nesterenko I 《Physical review letters》2000,84(17):3855-3858
We report on first measurements with polarized electrons stored in a medium-energy ring and with a polarized internal target. Polarized electrons were injected at 442 MeV (653 MeV), and a partial (full) Siberian snake was employed to preserve the polarization. Longitudinal polarization at the interaction point and polarization lifetime of the stored electrons were determined with laser backscattering. Spin observables were measured for electrodisintegration of polarized 3He, with simultaneous detection of scattered electrons, protons, neutrons, deuterons, and 3He nuclei, over a large phase space. 相似文献
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We analyze the resonant reflection of very weak, nonlinear sound waves off a weak sawtooth entropy wave for spatially periodic solutions of the one‐dimensional, nonisentropic gas dynamics equations. The case of an entropy wave with a sawtooth profile is of interest because the oscillations of the reflected sound waves are nondispersive with frequency independent of their wavenumber, leading to an unusual type of nonlinear dynamics. On an appropriate long time scale, we show that a complex amplitude function for the spatial profile of the sound waves satisfies a degenerate quasilinear Schrödinger equation. We present some numerical solutions of this equation that illustrate the generation of small spatial scales by a resonant four‐wave cascade and front propagation in compactly supported solutions. 相似文献
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Tkaczyk S Tollefson K Tollestrup A Toyoda H Trischuk W de Troconiz JF Tseng J Turini N Ukegawa F Valls J Vejcik S Velev G Vidal R Vilar R Volobouev I Vucinic D Wagner RG Wagner RL Wahl J Wallace NB Walsh AM Wang C Wang CH Wang MJ Watanabe T Waters D 《Physical review letters》2000,84(23):5273-5278
We have searched for direct production of scalar top quarks at the Collider Detector at Fermilab in 88 pb(-1) of p&pmacr; collisions at sqrt[s] = 1.8 TeV. We assume the scalar top quark decays into either a bottom quark and a chargino or a bottom quark, a lepton, and a scalar neutrino. The event signature for both decay scenarios is a lepton, missing transverse energy, and at least two b-quark jets. For a chargino mass of 90 GeV/c(2) and scalar neutrino masses of at least 40 GeV/c(2), we find no evidence for scalar top production and present upper limits on the production cross section in both decay scenarios. 相似文献