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91.
Coherent state path integrals are shown in general to contain instantons with jumps at the boundaries, i.e., boundary points lying outside classical phase space. Inclusion of these instantons is shown to resolve the "missing quench paradox" in the magnetic molecule Fe8, i.e., the fact that the tunneling between the ground Zeeman states of this molecule is quenched at only four magnetic field values, instead of the ten that would be expected from the topological Berry phase between interfering instantons. An approximate formula is found for the location of the four remaining quenches. 相似文献
92.
The network model approach for rigid and multi-rigid body systems developed recently [1,2] can also be used conveniently in formulating system equations or equations of motion of three-dimensional mechanical systems of interconnected rigid bodies. In this article, this method is further elaborated for establishing only the kinematics of spatial robotic bevel-gear trains. However the dynamic analysis of such systems using the same method is also possible and will be taken up in a future publication. 相似文献
93.
Muon capture on N > Z nuclei is proposed as a means of studying the T> isospin component of giant dipole states. Calculations for nickel isotopes (except 56Ni) indicate that these states are strongly excited by muon capture. Possible experiments to detect these states are discussed. 相似文献
94.
The theory of upper and lower bounds is used in conjunction with the “varied-portions approach” (VPA ) of the “many-electron theory of atoms and molecules” (MET ). Upper and lower bounds equations are derived. It is recognized that if a very natural portion of the full variational expression is made stationary, according to (VPA ), a for of Löwdin's lower bound wave equation results. By using the bracketing theorem it is also possible to give lower bounds to the quantities arising from the (VPA ) of (MET ). This will be useful to study in the future the (MET ) pair correlations and to supplement the computational methods currently available with lower bound estimates as well. 相似文献
95.
96.
The rapidly changing decision environment in electrical systems planning calls for a new approach in planning procedures and mathematical tools. The method proposed in this study decomposes the decision making into two strata, one at the strategy setting, the other at the project selection level. For the strategy setting level, a multiobjective dynamic linear programming model is used in generating system expansion decision alternatives. The suitability of the modelling approach is considered from the various aspects such as congruence, flexibility, transparency, and accuracy.An application of the model to the Turkish electrical system is also presented, where expansion alternatives to the year 2000 are generated. Three criteria were observed: cost, environmental impact and risk. 相似文献
97.
The effect of electron-electron interactions on the surface states of ionicd-band oxides is reported. The local density of states of surface cations in the valence band region is significantly increased
when surface states occur in the band gap. Coulomb repulsion associated with thissurface enhanced covalency tends to force surface states out of the band gap. These results suggest an explanation of recent experiments on SrTiO3 and TiO2. 相似文献
98.
J.?BijnensEmail author F.?Borg 《The European Physical Journal C - Particles and Fields》2005,39(3):347-357
The five different CP conserving amplitudes for the decays
are calculated using Chiral Perturbation Theory. The calculation is made to next-to-leading order and includes full isospin
breaking. The squared amplitudes are compared with the corresponding ones in the isospin limit to estimate the size of the
isospin breaking effects. In this paper we add the radiative corrections to the earlier calculated m
u
-m
d
and local electromagnetic effects. We find corrections of order 5-10 percent.
Received: 8 November 2004, Published online: 18 January 2005
PACS:
13.20.Eb; 12.39.Fe; 14.40.Aq; 11.30.Rd 相似文献
99.
T.?Sj?strandEmail author P.?Z.?Skands 《The European Physical Journal C - Particles and Fields》2005,39(2):129-154
We propose a sophisticated framework for high-energy hadronic collisions, wherein different QCD physics processes are interleaved in a common sequence of falling transverse-momentum values. Thereby phase-space competition is introduced between multiple parton-parton interactions and initial-state radiation. As a first step we develop new transverse-momentum-ordered showers for initial- and final-state radiation, which should be of use also beyond the scope of the current article. These showers are then applied in the context of multiple interactions, and a few tests of the new model are presented. The article concludes with an outlook on further aspects, such as the possibility of a shower branching giving partons participating in two different interactions.Received: 26 August 2004, Revised: 14 October 2004, Published online: 11 January 2005 相似文献
100.
A conformally flat accelerated charge metric is found in an arbitrary dimension D. It is a solution of the Einstein-Maxwell-null fluid equations with a cosmological constant in D ≥ 4 dimensions. When the acceleration is zero, our solution reduces to the Levi-Civita-Bertotti-Robinson metric. We show
that the charge loses its energy, for all dimensions, due to the acceleration. 相似文献