共查询到20条相似文献,搜索用时 125 毫秒
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在现有的弱电统一理论中,认为应当存在自旋为零的粒子(Higgs粒 ),并且通过“Higgs机制”实现真空对称性自发破缺.这个理论的许多重要预言都得到了实验上广泛的证实,但始终没有找到在理论上起核心作用的Higgs粒子本身.粒子物理学面临一个十分重要的课题.本文从理论和实验两个方面就这个问题进行了评述,其中包括介绍Higgs机制和寻找Higgs粒子的现状及意义. 相似文献
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氖(Ne)和氩(Ar)原子的sp型弥散函数 总被引:1,自引:0,他引:1
氖(Ne)和氩(Ar)原子的sp型弥散函数苏克和西北工业大学化工系西安710072CarolA.DeakyneDepartmentofChemistry,EasternIllinoisUniv,U.S.ANe和Ar原子的sp型弥散函数在文献[1-2]... 相似文献
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用Migdal-Kadanoff重整化群方法对Z4Higgs场─—规范场体系进行了研究,给出了四维时空的相互作用耦合常数递推关系和体系的相图,发现Higgs相与禁闭相是连通的. 相似文献
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FormationandConfirmationofthe“Pure”LaserInducedPopulationGratinginDyeSolution¥ZHOUD.J.;LIR.H.;ZHENGY.Z.(InstituteofLaserandSp... 相似文献
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TheDynamicBehaviourAnalysisofUp-ConversionLuminescenceinErP_5O_(14)GlassTheDynamicBehaviourAnalysisofUp-ConversionLuminescence... 相似文献
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The dynamics of the short-range order as well as the long-range order in the nonlinear cooperative system is investigated specifically for a kinetic Ising model in the Bethe approximation. The phenomena of critical slowing down near the transition temperatureT
c
and anomalous fluctuation belowT
c
are directly related to the instability of the long-range order. The dynamics of the short-range order is essentially a fast mode and is noncritical. However, through the nonlinear coupling the short-range order is also influenced by the critical behavior of the long-range order. 相似文献
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The anomalies of the second order elastic constants have been derived for barium titanate for the phase transition from cubic
to tetragonal. The equilibrium values of the components of the order parameter and the strain variables have been obtained
from the stability conditions. The fluctuations in the order parameter have been derived from the Landau-Khalatnikov equations.
Expression for the shift in the zero point energy in the tetragonal phase is obtained and is shown to be proportional to (T −T
c)2. The anomalies for all the second order elastic constants have been derived and relations among them reported. It is shown
that the second order elastic anomalies suffer a discontinuity at the transition temperature. 相似文献
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D. Nicolaides 《Phase Transitions》2013,86(8):655-665
Phase transitions in magnets, described by two coupled, m-component vector order parameters, having uniform uniaxial anisotropies are studied. Using a phenomenological model, it is shown that when both order parameters are anisotropic, phase transitions are always second order, in either the uniaxial or the (m???1)-isotropic phase. This is contrary to the isotropic case of two coupled order parameters, for which phase transitions are fluctuation-induced first order. The transitions are still continuous into the m-isotropic phase even when the only anisotropic order parameter is the one with the lowest mean-field critical temperature. New discontinuous transitions still occur in either the uniaxial or the (m???1)-isotropic phase, when the only anisotropic order parameter has the highest mean-field critical temperature. 相似文献
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Second order elastic anomalies in barium titanate from orthorhombic to rhombohedral phase transition
B Subramanyam 《Pramana》1994,43(3):181-187
The anomalies in second order elastic constants have been derived for barium titanate for the phase transition from orthorhombic
to rhombohedral state. The equilibrium values of order parameter, strain variables and fluctuations in order parameter have
been derived using stability conditions and Landau-Khalatnikov equations respectively. Expression for shift in specific heat
is obtained. All the anomalies in second order elastic constants have been derived and relations among them reported. The
numerical values of anomalies in the individual constants are calculated and their variation is represented graphically. Changes
in elastic constants occur over a range of temperature of the order 10−2K. 相似文献
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The analytical expression for the propagation of a flattened laser beam array in a turbulent atmosphere is derived based on extended Huygens–Fresnel principle. The influence of beam order and turbulent atmosphere on beam quality is studied. It is revealed that the beam quality of a coherently combined laser beam array with higher order is better than its lower order counterpart when propagating in free-space, weak and medium turbulence (i.e. Cn2<10?13 m?2/3). The beam quality of higher order beam arrays degrades faster as the intensity of turbulence gets stronger. In the case of propagating in strong turbulence, the beam order has no influence on coherently combined beam quality. 相似文献
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The internal conical refraction of a Bessel beam of arbitrary order is studied theoretically. It is shown that a beam of the order m of arbitrary polarization in the general case is partially converted to Bessel beams of the order m ± 1 with orthogonal circular polarizations. Conditions for complete conversion of a beam of the order m to a Bessel beam of the order m?1 or m+1 are determined. 相似文献
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The phase diagram of a layered superconductor in a large parallel magnetic field is calculated. This includes a calculation of the lower critical field beyond which the superconductor is in the FFLO-state and possesses a spatially modulated order parameter and spin polarization. The order parameter, spin polarization, free-energy density, and phase boundaries of this unconventional superconducting phase are evaluated numerically in the complete B–T plane. The analysis suggests that the transition at the lower critical field is of second order, and not of first order, as previously assumed. The order parameter of the FFLO-state merges continuously into the uniform superconducting state. 相似文献
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Dipalmitoyllecithin (DPL) shows an order ← → disorder pressure transition which is neither of first order nor of second order
but can be treated as a fractional order (3/2 order) transition. The Ising model formalism is adopted for the study of such
a system. A suitable equilibrium constant is defined which generates a 3/2 order transition. Transition curves are obtained
and compared with the experimental curves of Liu and Kay. Reverse transition curves are also obtained and the system exhibits
hysteresis effect. An approximate expression connecting transition pressures at different temperatures is obtained and the
calculated and the experimental values are in good agreement. 相似文献
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The spatial localization of the heteronuclear scalar order produced for an AX N spin-1/2 system by adiabatic demagnetization in the rotating frame is discussed. The density operator formalism is used for an exact evaluation of the produced scalar order in the presence of the main field gradient. A pulse sequence to record the scalar order profile is presented. 相似文献