共查询到20条相似文献,搜索用时 15 毫秒
1.
《Physics letters. A》1986,114(6):322-326
Our earlier work on the correlation-induced-disorder effect in a one-dimensional system has been extended to two and three dimensions to demonstrate that relative to the external disorder, such effect is more important in higher dimension than in one dimension. 相似文献
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By comparing the cross sections for left- and right-handed electrons scattered from various unpolarized nuclear targets, the small parity-violating asymmetry can be measured. These asymmetry data probe a wide variety of important topics, including searches for new fundamental interactions and important features of nuclear structure that cannot be studied with other probes. A special feature of these experiments is that the results are interpreted with remarkably few theoretical uncertainties, which justifies pushing the experiments to the highest possible precision. To measure the small asymmetries accurately, a number of novel experimental techniques have been developed. 相似文献
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Parity-violating pion-proton scattering is strongly dominated by so-called penguin operators. These operators are due to the presence of the neutral current, and their strength is further enhanced by the QCD renormalization effects. Without such contributions the elastic asymmetry (Al) would be an order of magnitude smaller (up to 150 MeV of the pion laboratory kinetic energy). Possible contributions from the resonance poles (?-meson, () have been also included. Thus pion scattering on the polarized proton can test the commonly-used effective QCD renormalized weak hamiltonian. 相似文献
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C. -P. Liu 《Hyperfine Interactions》2013,214(1-3):173-179
Nuclear few-body systems become attractive avenues for the study of low-energy parity violation because experiments start to meet the precision requirements and theoretical calculations can be performed reliably. In this talk, an attempt of parametrizing low-energy parity-violating observables by the Danilov parameters will be introduced. Analyses of two-nucleon observables, based on the modern phenomenological potentials or the one of effective field theory, will be discussed. 相似文献
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S. Kowalski 《The European Physical Journal A - Hadrons and Nuclei》2006,29(1):101-105
Approximations based on the 2PI effective action are used to investigate the process of equilibration in ϕ4 theory in 3+1 dimensions, both in the symmetric and broken phase. A special emphasis is put on the study of the kinetic and
chemical equilibration. 相似文献
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The 2S-1S transition in light muonic atoms is very sensitive to parity violation correlations induced via neutral currents. Observables depending on these transitions such as the photon polarization and the angular correlation between the emitted radiation and the atom polarization are a clear signal of weak neutral currents in atoms. We find the relation between the lepton and quark couplings and these observables emphasizing the effect of the nuclear spin. The results expected in muonic, atoms μ-4He and μ-3He are given. 相似文献
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We have measured a parity violation in the 6S–7S transition of Cs in an electric field. Our result is Im is the parity violating electric dipole amplitude, ß is the vector polarizability. This result is consistent with the Weinberg-Salam prediction. 相似文献
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Preliminary calculations show that the parity violating asymmetry in polarised electron deuteron elastic scattering can be as large as observed in the SLAC experiment even in the intermediate energy region. We propose that experiments should be done to search for these asymmetries. 相似文献
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The parity violating effective interaction in models based on the SU(2)L × SU(2)R × U(1) gauge group is shown to have the same structure, at zero momentum transfer, as in the Weinberg-Salam model, apart from a constant scale factor. 相似文献
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《Physics letters. [Part B]》1986,175(2):176-178
A diagrammatic computation of the parity-breaking gravitational effective action induced by massless fermions in three dimensions is presented. The lowest-order approximation to the Chern-Simons action is obtained, in agreement with a general index-theoretic result. 相似文献
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The spectrum of a photoexcited electron pair carries detailed information on the electron-electron interaction in metals. This is deduced from the results of a theoretical model presented here for the treatment of the double-photoelectron emission from surfaces. Main features in the two-particle spectra are assigned to (a) the exchange-correlation interaction, (b) the electronic band structure, (c) the photoelectron diffraction, and (d) the specific experimental setup. Comparison with experiments is made and common features and differences to the atomic case are pointed out. 相似文献
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The parity violation induced by weak neutral currents is measured in a ΔF=1 hyperfine component of the 6S–7S transition of the Cs atom. The measured value (statistical rms deviation) ±0.12 (systematic uncertainty) mV/cm, agrees with our previous measurement in a ΔF=0 component, and constitutes an important cross-check. Our result excludes a parity violation induced by a purely axial hadronic neutral current. 相似文献
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G. A. Lobov 《Physics of Atomic Nuclei》2000,63(8):1387-1390
On the basis of an analysis of experimental data, it is shown that a subthreshold (negative) p-wave resonance can exist in the 204Pb isotope at E p =?16 eV. The presence of this resonance may explain unexpectedly large values observed experimentally for the P-odd angle of the rotation of the spin of transversely polarized neutrons about their momentum that are scattered on a natural mixture of lead isotopes. No available data are at odds with the existence of the E p =?16 eV subthreshold resonance in 204Pb. 相似文献
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We investigate radiative pion capture in hydrogen, π? → nγ, as a means of determining the parity-violating πNN coupling constant ?π. We include contributions from the lightest baryon resonance [Δ(1232)] and the light vector mesons [ρ, ω, φ]. Our results indicate that, despite their negligible role in parity-conserving amplitudes, the effects of the Δ and ρ may hamper the determination of ?π. 相似文献