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991.
We propose a new approach for the study of the time evolution of a factorized N-particle bosonic wave function with respect to a mean-field dynamics with a bounded interaction potential. The new technique, which is based on the control of the growth of the correlations among the particles, leads to quantitative bounds on the difference between the many-particle Schrödinger dynamics and the one-particle nonlinear Hartree dynamics. In particular the one-particle density matrix associated with the solution to the N-particle Schrödinger equation is shown to converge to the projection onto the one-dimensional subspace spanned by the solution to the Hartree equation with a speed of convergence of order 1/N for all fixed times. 相似文献
992.
José Natário 《General Relativity and Gravitation》2009,41(11):2579-2586
We construct a coordinate system for the Kerr solution, based on the zero angular momentum observers dropped from infinity,
which generalizes the Painlevé–Gullstrand coordinate system for the Schwarzschild solution. The Kerr metric can then be interpreted
as describing space flowing on a (curved) Riemannian 3-manifold. The stationary limit arises as the set of points on this
manifold where the speed of the flow equals the speed of light, and the horizons as the set of points where the radial speed equals the speed of light. A deeper analysis of what is meant by the flow of space reveals that the acceleration of
free-falling objects is generally not in the direction of this flow. Finally, we compare the new coordinate system with the closely related Doran coordinate system. 相似文献
993.
Jan Kapitán 《The European Physical Journal C - Particles and Fields》2009,62(1):217-221
Anisotropic flow measurements have demonstrated development of partonic collectivity in 200 GeV Au+Au collisions at RHIC.
To understand the partonic EOS, thermalization must be addressed. Collective motion of heavy-flavor (c, b) quarks can be used
to indicate the degree of thermalization of the light-flavor quarks (u, d, s). Measurement of heavy-flavor quark collectivity
requires direct reconstruction of heavy-flavor hadrons in the low p
T region. Measurement of open charm spectra to high p
T can be used to investigate heavy-quark energy loss and medium properties. The Heavy Flavor Tracker (HFT), a proposed upgrade
to the STAR experiment at midrapidity, will measure v
2 of open-charm hadrons to very low p
T by reconstructing their displaced decay vertices. The innermost part of the HFT is the PIXEL detector (made of two low mass
monolithic active pixel sensor layers), which delivers a high precision position measurement close to the collision vertex.
The Intermediate Silicon Tracker (IST), a 1-layer strip detector, is essential to improve hit identification in the PIXEL
detector when running at full RHIC-II luminosity. Using a full GEANT simulation, open charm measurement capabilities of STAR
with the HFT will be shown. Its performance in a broad p
T range will be demonstrated on v
2 (p
T>0.5 GeV/c) and R
CP (p
T<10 GeV/c) measurements of D0 meson. Results of reconstruction of ΛC baryon in heavy-ion collisions are presented. 相似文献
994.
Absorption and luminiscence measurements were performed on lead-doped KCl:KI mixed single crystals. Strong differences were found between as-grown and quenched samples. New bands were observed in the absorption spectra of unquenched samples in the spectral region between the limit positions of the A bands, corresponding to chloride or iodide lattices. The strong band at 449 nm dominates the luminescence of these samples at low temperatures. Its kinetics have a complicated form and the decay time is in the interval from ns to ms. Quenched samples have a well-known luminescence spectrum caused by octahedral lead impurity centres in KCl single crystals. The kinetics, however, also indicate mixed chlorine and iodine coordination of lead in the investigated crystals. 相似文献
995.
M.?Bogu?áEmail author J.?Masoliver 《The European Physical Journal B - Condensed Matter and Complex Systems》2004,40(3):347-352
We revisit the problem of daily correlations in speculative prices and report empirical evidences on the existence of what we term a conditional or dual dynamics driving the evolution of financial assets. This dynamics is detected in several markets around the world and for different historical periods. In particular, we have analyzed the DJIA database from 1900 to 2002 as well as 65 companies trading in the LIFFE market of futures and 12 of the major European and American treasury bonds. In all cases, we find a twofold dynamics driving the financial evolution depending on whether the previous price went up or down. We conjecture that this effect is universal and intrinsic to all markets.Received: 14 April 2004, Published online: 31 August 2004PACS:
89.65.Gh Economics; econophysics, financial markets, business and management - 05.45.Tp Time series analysis - 87.23.Ge Dynamics of social systems 相似文献
996.
Fajardo M. Pérez Alcázar G. A. Moreira A. M. Speziali N. L. 《Hyperfine Interactions》2004,158(1-4):395-400
The local environment of implanted 111Ag (t
1/2 = 7.45 d) in single-crystalline [0001] ZnO was evaluated by means of the perturbed angular correlation (PAC) technique. Following
the 60 keV low dose (1 × 1013 cm−2) 111Ag implantation, the PAC measurements were performed for the as-implanted state and following 30 min air annealing steps,
at temperatures ranging from 200 to 1050°C. The results revealed that 42% of the probes are located at defect-free SZn sites (ν
Q ∼ 32 MHz, η = 0) in the as-implanted state and that this fraction did not significantly change with annealing. Moreover, a progressive
lattice recovery in the near vicinity of the probes was observed. Different EFGs assigned to point defects were furthermore
measured and a general modification of their parameters occurred after 600°C. The 900°C annealing induced the loss of 30%
of the 111Ag atoms, 7% of which were located in regions of high defects concentration. 相似文献
997.
Yu Ts Oganessian A. V. Yeremin A. G. Popeko O. N. Malyshev A. V. Belozerov G. V. Buklanov M. L. Chelnokov V. I. Chepigin V. A. Gorshkov S. Hofmann M. G. Itkis A. P. Kabachenko B. Kindler G. Münzenberg R. N. Sagaidak Š Šáro H.-J. Schött B. Štreicher A. V. Shutov A. I. Svirikhin G. K. Vostokin 《The European Physical Journal A - Hadrons and Nuclei》2004,19(1):3-6
The upgraded separator VASSILISSA was used to confirm results of previous experiments on the synthesis of the heavy isotopes of the element 112 obtained in complete-fusion reactions of 48Ca and 238U. An additional reason was the non-observation of any events in the same reaction studied with the BGS separator at Berkeley. Limits of
for the atomic mass number of the observed spontaneously fissioning isotope were measured. The obtained results on the decay mode, half-life and production cross-section are in agreement with those obtained in our first experiment.Received: 10 June 2003, Revised: 29 July 2003, Published online: 2 December 2003PACS:
23.60. + e
decay - 25.70.-z Low and intermediate energy heavy-ion reactions - 25.85.Ca Spontaneous fission - 27.90. + b
相似文献
998.
P.?SantiagoEmail author J.A.?Ascencio D.?Mendoza M.?Pérez-Alvarez A.?Espinosa C.?Reza-SanGermán P.?Schabes-Retchkiman G.A.?Camacho-Bragado M.?José-Yacamán 《Applied Physics A: Materials Science & Processing》2004,78(4):513-518
In the present work we report the synthesis of MoS2 nanotubes with diameters greater than 10 nm using a template method. The length and properties of these nanotubes are a direct result of the preparation method. High-resolution transmission electron microscopy is used to study the structure of these highly curved entities. Molecular dynamics simulations of MoS2 nanotubes reveal that one of the stable forms of the nanotubes is a twisted one. The twisting of the nanotubes produces a characteristic contrast in the images, which is also studied using simulation methods. The analysis of the local contrast close to the perpendicular orientation shows geometrical arrays of dots in domain-like structures, which are demonstrated to be a product of the atomic overlapping of irregular curvatures in the nanotubes. The configuration of some of the experimentally obtained nanotubes is demonstrated to be twisted with a behavior suggesting partial plasticity. PACS 61.16.Bg; 79.60.Jv; 61.46.+w; 61.50.Ah 相似文献
999.
V. A. Khitrov C. Panteleev A. M. Sukhovoj J. Honzátko I. Tomandl 《Physics of Atomic Nuclei》2004,67(10):1818-1822
Main properties of the excited states of 118Sn manifesting themselves in cascade γ decay of its compound state are studied. As in heavier nuclei studied earlier, qualitative interpretation of the whole set
of observed properties of the nucleus appears to be impossible without accounting for coexistence and interaction of quasiparticle
and collective nuclear excitations and their considerable influence on the main parameters of the process under study.
From Yadernaya Fizika, Vol. 67, No. 10, 2004, pp. 1845–1849.
Original English Text Copyright ? 2004 by Khitrov, Panteleev, Sukhovoj, Honzátko, Tomandl.
This article was submitted by the authors in English. 相似文献
1000.
J.J.?RomeroEmail author M.R.B.?Andreeta E.R.M.?Andreeta L.E.?Bausá A.C.?Hernandes J.?García Solé 《Applied Physics A: Materials Science & Processing》2004,78(7):1037-1042
The growth from ceramic pedestals of single crystal fibers of strontium barium niobate (SBN), doped with different Nd concentrations, was studied. High-quality fibers were grown for Nd doping levels of up to 4.2 at.%, and doping levels as high as 9.9 at.% were reached. No signs of core effects were observed, even for the highest concentration samples. The emission spectra of Nd3+ ions in the fibers did not differ from those obtained from bulk SBN crystals, showing very broad bands due to the typical disorder of the crystallographic tungsten-bronze structure. Fluorescence quenching was clearly observed for Nd doping levels above 2 at.%. PACS 81.10.Fq; 78.55.-m 相似文献