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61.
62.
Femtosecond three-pulse photon-echo studies of acetic acid dimers in solution reveal multilevel coherence of O-H stretching excitations caused by the anharmonic coupling between the high-frequency stretching and low-frequency hydrogen-bond motions. We demonstrate for the first time that such multilevel coherence determines the nonexponential decay of the macroscopic O-H stretching polarization, whereas spectral diffusion processes play a minor role. The dephasing time of individual vibrational transitions contributing to the overall polarization is approximately 200 fs.  相似文献   
63.

We formulate and prove a topological Paley-Wiener theorem for the normalized spherical Laplace transform defined on the rank 1 causal symmetric spaces , for .

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The exact static and spherically symmetric solutions of the vacuum field equations for a Higgs Scalar-Tensor theory (HSTT) are derived in Schwarzschild coordinates. It is shown that in general there exists no Schwarzschild horizon and that the fields are only singular (as naked singularity) at the center (i.e. for the case of a point-particle). However, the Schwarzschild solution as in usual general relativity (GR) is obtained for the vanishing limit of Higgs field excitations.  相似文献   
66.
The characteristic connection of an almost hermitian structure is a hermitian connection with totally skew-symmetric torsion. The case of parallel torsion in dimension 6 is of particular interest. In this work, we give a full classification of the algebraic types of the torsion form, and, on the basis of this, undertake a systematic investigation into the possible geometries. Numerous naturally reductive spaces are constructed and classified, and examples on nilmanifolds given.  相似文献   
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In current QCD inspired analyses of the hadron spectrum nonperturbative quark loops are generally neglected. We study the validity of this assumption by estimating mass splittings and mixings induced by hadronic mass renormalization to the (70,1?) baryon multiplet. All intermediate states in the loop composed of a ground state meson (0?+, 1??) and a ground state baryon (1/2+, 3/2+) are included. We use a3 P 0 type model for the partial decay widths and spectral functions. Using unitarity and analyticity one finds a definite prediction for the masses and mixings, in good agreement with experiment, even when the perturbative one-gluon exchange is completely ignored. Our result thus allows for a smaller one-gluon exchange overall contribution, which would resolve the difficulty of the apparent smallness of the observed spin-orbit coupling. In particular if one adds the (nonperturbative) unitarity corrections to the one-gluon exchange contribution the gluon coupling constant can be reduced by a factor of 3 giving a reasonable value αs≈0.3.  相似文献   
69.
In this paper, the one-way absorption property in one-dimensional dielectric/metal photonic crystal structure with a dielectric defect layer is studied. The effects of incident angle and state of polarization on one-way absorption behaviour of the anti-resonant (AR) mode are investigated. The normally incident wave from left to right propagation is totally allowed to penetrate to the structure but right to left propagation totally reflected at the same wavelength. It is found that, with increasing of the incident angle, the AR mode shifts to the lower wavelengths and its intensity decreases. Simultaneously, another AR mode with reversed one-way property appears at higher wavelength. The one-way behaviour on absorption is observed at the both states of polarizations but is localized on different wavelengths. Those effects, are suggesting that the proposed structure can be used as a direction sense polarization splitter or reflector/antireflector device.  相似文献   
70.
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