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排序方式: 共有695条查询结果,搜索用时 15 毫秒
121.
This paper presents DELPHI measurements and interpretations of cross-sections, forward-backward asymmetries, and angular distributions,
for the
process for centre-of-mass energies above the Z resonance, from
-207 GeV at the LEP collider. The measurements are consistent with the predictions of the Standard Model and are used to study
a variety of models including the S-Matrix ansatz for
scattering and several models which include physics beyond the Standard Model: the exchange of Z′ bosons, contact interactions
between fermions, the exchange of gravitons in large extra dimensions and the exchange of
in R-parity violating supersymmetry.
This paper is dedicated to the memory of Alan Segar. 相似文献
122.
The L Collaboration 《The European Physical Journal C - Particles and Fields》2006,45(3):569-587
The mass and the total decay width of the W boson are measured with the L3 detector at the LEP e+e– collider using W-boson pairs produced in 0.7 fb–1 of data collected at centre-of-mass energies between 161 and 209 GeV. Combining semi-leptonic and fully-hadronic final states,
the mass and the width of the W boson are determined to be
where the first uncertainty is statistical and the second systematic. 相似文献
123.
Calzavarini E Cencini M Lohse D Toschi F;International Collaboration for Turbulence Research 《Physical review letters》2008,101(8):084504
Particles with different density from the advecting turbulent fluids cluster due to the different response of light and heavy particles to turbulent fluctuations. This study focuses on the quantitative characterization of the segregation of dilute polydisperse inertial particles evolving in turbulent flow, as obtained from direct numerical simulation of homogeneous isotropic turbulence. We introduce an indicator of segregation amongst particles of different inertia and/or size, from which a length scale r_{seg}, quantifying the segregation degree between two particle types, is deduced. 相似文献
124.
Abouzaid E Arenton M Barker AR Bellantoni L Bellavance A Blucher E Bock GJ Cheu E Coleman R Corcoran MD Cox B Erwin AR Escobar CO Glazov A Golossanov A Gomes RA Gouffon P Hsiung YB Jensen DA Kessler R Kotera K Ledovskoy A McBride PL Monnier E Nguyen H Niclasen R Ii DG Ping H Ramberg EJ Ray RE Ronquest M Santos E Slater W Smith D Solomey N Swallow EC Toale PA Tschirhart R Wah YW Wang J White HB Whitmore J Wilking MJ Winstein B Winston R Wolfe C Worcester ET Worcester M Yamanaka T Zimmerman ED 《Physical review letters》2008,100(13):131803
The Fermilab KTeV experiment has searched for lepton-flavor-violating decays of the K(L) meson in three decay modes. We observe no events in the signal region for any of the modes studied, and we set the following upper limits for their branching ratios at the 90% C.L.: BR(K(L) --> pi(0) micro(+/-) e(-/+)) <7.6 x 10(-11); BR(K(L) --> pi(0)pi(0) micro(+/-) e(-/+)) <1.7 x 10(-10); BR(pi(0) --> micro(+/-) e(-/+)) <3.6 x 10(-10). This result represents a factor of 82 improvement in the branching ratio limit for K(L) --> pi(0) micro(+/-) e(-/+) and is the first reported limit for K(L) --> pi(0)pi(0) micro(+/-) e(-/+). 相似文献
125.
Smilowitz L Henson BF Romero JJ Asay BW Schwartz CL Saunders A Merrill FE Morris CL Kwiatkowski K Hogan G Nedrow P Murray MM Thompson TN McNeil W Rightley P Marr-Lyon M;pRad Collaboration 《Physical review letters》2008,100(22):228301
We present a new phenomenology for burn propagation inside a thermal explosion based on dynamic radiography. Radiographic images were obtained of an aluminum cased solid cylindrical sample of a plastic bonded formulation of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine. The phenomenology observed is ignition followed by cracking in the solid accompanied by the propagation of a radially symmetric front of increasing proton transmission. This is followed by a further increase in transmission through the sample, ending after approximately 100 micros. We show that these processes are consistent with the propagation of a convective burn front followed by consumption of the remaining solid by conductive particle burning. 相似文献
126.
H. Masenda S. Geburt K. Bharuth-Ram D. Naidoo H. P. Gunnlaugsson K. Johnston R. Mantovan T. E. Mølholt M. Ncube S. Shayestehaminzadeh H. P. Gislason G. Langouche S. Ólafsson C. Ronning ISOLDE Collaboration 《Hyperfine Interactions》2016,237(1):40
Emission Mössbauer Spectroscopy following the implantation of radioactive precursor isotope 57Mn+ (T 1/2= 1.5 min) into ZnO single crystals at ISOLDE/CERN shows that a large fraction of 57Fe atoms produced in the 57Mn beta decay is created as paramagnetic Fe3+ with relatively long spin-lattice relaxation times. Here we report on ZnO pre-implanted with 56Fe to fluences of 2×1013, 5×10 13 and 8 × 1013 ions/cm2 in order to investigate the dependence of the paramagnetic relaxation rate of Fe3+ on fluence. The spectra are dominated by magnetic features displaying paramagnetic relaxation effects. The extracted spin-lattice relaxation rates show a slight increase with increasing ion fluence at corresponding temperatures and the area fraction of Fe3+ at room temperature reaches a maximum contribution of 80(3)% in the studied fluence range. 相似文献
127.
The COSY-TOF Collaboration S.?Jowzaee E.?Borodina H.?Clement E.?Doroshkevich R.?Dzhygadlo K.?Ehrhardt W.?Eyrich W.?Gast A.?Gillitzer D.?Grzonka F.?Hauenstein P.?Klaja L.?Kober K.?Kilian M.?Krapp M.?Mertens P.?Moskal J.?Ritman E.?RoderburgEmail author M.?R?der W.?Schroeder T.?Sefzick J.?Smyrski P.?Wintz P.?Wüstner 《The European Physical Journal A - Hadrons and Nuclei》2016,52(1):7
128.
S. Heinz E. Berdermann F. Heine O. Joeres P. Kienle I. Koenig W. Koenig C. Kozhuharov U. Leinberger M. Rhein A. Schröter H. Tsertos The ORANGE Collaboration at GSI 《The European Physical Journal A - Hadrons and Nuclei》2000,9(1):55-61
We present new results from measurements and simulations of positron spectra, originating from 238U + 181Ta collisions at beam energies close to the Coulomb barrier. The measurements were performed using an improved experimental
setup at the double-Orange spectrometer of GSI. Particular emphasis is put on the signature of positrons from Internal-Pair-Conversion
(IPC) processes in the measured e+-energy spectra, following the de-excitation of electromagnetic transitions in the moving Ta-like nucleus. It is shown by
Monte Carlo simulations that, for the chosen current sweeping procedure used in the present experiments, positron emission
from discrete IPC transitions can lead to rather narrow line structures in the measured energy spectra. The measured positron
spectra do not show evidence for line structures within the statistical accuracy achieved, although expected from the intensities
of the observed γ-transitions ( E
γ∼ 1250-1600 keV) and theoretical conversion coefficients. This is due to the reduced detection efficiency for IPC positrons,
caused by the limited spatial and momentum acceptance of the spectrometer. A comparison with previous results, in which lines
have been observed, is presented and the implications are discussed.
Received: 27 April 2000 / Accepted: 14 September 2000 相似文献
129.
T. Kautzsch W.B. Walters M. Hannawald K.-L. Kratz V.I. Mishin V.N. Fedoseyev W. Böhmer Y. Jading P. Van Duppen B. Pfeiffer A. Wöhr P. Möller I. Klöckl V. Sebastian U. Köster M. Koizumi J. Lettry H.L. Ravn the ISOLDE Collaboration 《The European Physical Journal A - Hadrons and Nuclei》2000,9(2):201-206
A chemically selective laser ion source has been used in a β-decay study of heavy Ag isotopes into even-even Cd nuclides.
Gamma-spectroscopic techniques in time-resolving event-by-event and multiscaling modes have permitted the identification of
the first 2+ and 4+ levels in 126Cd78, 128Cd80, and tentatively the 2+ state in 130Cd82. From a comparison of these new states in 48Cd with the E(2+) and E(4+)/E(2+) level systematics of 46Pd and 52Te isotopes and several recent model predictions, possible evidence for a weakening of the spherical N = 82 neutron-shell below double-magic 132Sn is obtained.
Received: 13 July 2000 / Accepted: 12 October 2000 相似文献
130.
BES Collaboration 《中国物理C(英文版)》1997,21(1):89-96
The hadronic decays ψ(2S)→ρα2 and K*0K2*0+c.c. have been studied in a sample of 3.6×106 ψ(2S) events.Measurements of their branching fractions are presented.Both channels violate the “15% rule” predicted by perturbative QCD compared with the corresponding J/ψ decays.These results serve as new examples of abnormal suppression of ψ(2S) decays into vector-tensor final states that was first observed in ψ(2S)→ωf2 相似文献