共查询到20条相似文献,搜索用时 15 毫秒
1.
B. Jancovici 《Journal of statistical physics》2000,100(1-2):201-207
In a two-dimensional, two-component plasma, the second moment of the density correlation function has the simple value {12[1–(/4)]2}–1, where is the dimensionless coupling constant. This result is derived by using analogies with critical systems. 相似文献
2.
Nils Offen 《Few-Body Systems》2016,57(10):975-983
3.
We fabricate a photonic crystal microcavity containing Alq3 in a sandwiched structure by the self-assemble method. The angle-dependent photoluminescence (PL) spectra and the variation of the PL lifetime demonstrate the effect of the photonic band gap on the spontaneous emission of Alq3 in the photonic crystals. 相似文献
4.
ZHU Wei 《中国物理C(英文版)》1993,17(8):714-716
We have discussed the effect of valence quark mixing in DIS process.This effect,together with the pion cloud effect,dominates the violation of Gottfried sum rule. 相似文献
5.
量子色动力学(QCD)求和规则是强子物理研究中的一种重要的非微扰方法, 已经成为强子物理与核物理研究中有力的工具。 简单介绍了QCD求和规则的基本概念、 方法与应用, 特别讨论了QCD求和规则近年来的发展和与之相关的一些前沿问题。 QCD sum rule is an important nonperturbative method in hadron physics, it has been a powerful technique in study of hadron physics and nuclear physics.We give a brief introduction to the basic idea, the method and its application of QCD sum rule, emphasize the development of this method and some topics in recent years. 相似文献
6.
We calculate the nucleon self-energies in an isospin asymmetric nuclear matter using QCD sum rule. Taking the difference of these for the neutron and proton enables us to express an important part of the nuclear symmetry energy in terms of local operators. Calculating the operator product expansion up to mass dimension six operators, we find that the main contribution to the difference comes from the iso-vector scalar and vector operators, which is reminiscent to the case of relativistic mean field type theories where mesons with aforementioned quantum numbers produce the difference and provide the dominant mechanism for nuclear symmetry energy. 相似文献
7.
Valuation functions of observables in quantum mechanics are often expected to obey two constraints called the sum rule and product rule. However, the Kochen-Specker (KS) theorem shows that for a Hilbert space of quantum mechanics of dimension d ≥ 3, these constraints contradict individually with the assumption of value definiteness. The two rules are not irrelated and Peres [Found. Phys. 26 (1996)807] has conceived a method of converting the product rule into a sum rule for the case of two qubits. Here we apply this method to a proof provided by Mermin based on the product rule for a three-qubit system involving nine operators. We provide the conversion of this proof to one based on sum rule involving ten operators. 相似文献
8.
在组分夸克模型中重子共振态的光子激发下,通过数值计算核子上光子总吸收截面σ1/2和σ3/2,检验了Gerasimov–Drell–Heam(GDH)求和规则.这种计算包括了总计17个低激发的、非奇异重子共振态.发现纵横相干截面在随Q2变化的求和规则研究中扮演了重要角色.结果显示在94%可信度上这些共振态使GDH求和规则饱和.特别是在Q2=0和小Q2的区域,主要是共振态P33(1232)激发使求和规则饱和.在Q2=1.0GeV2以下,GDH积分有一个很强的Q2依赖性质,且在Q2=0.3GeV2附近变号.由于共振态贡献的迅速下降,当Q2>1.0GeV2时,GDH积分对Q2依赖变弱. 相似文献
9.
简要回顾了量子色动力学求和规则在计算s夸克质量方面的应用.结合Dominguez,Gend和Paver的工作,重新考虑渐近自由阈以下的谱函数后,计算了s夸克的质量,得到s夸克的跑动质量(-m)s(1 GeV)=219 MeV.讨论了影响计算结果精度的可能因素. 相似文献
10.
MA ZhongYu 《理论物理通讯》1999,32(4):493-498
A fully consistent relativistic random-phase approximation (RRPA) is studied in the sense that the relativistic mean-field (RMF) wavefunction of nucleus and the particlehole residual interactions in the RRPA are calculated from the same effective Lagrangian. A consistent treatment of RRPA within the RMF approximation, i.e., no sea approximation, has to include also the pairs formed from the Dirac states and occupied Fermi states, which is essential for satisfying the current conservation. The inverse energy-weighted sum rule for the isoscalar giant monopole mode is investigated in the constrained RMF. It is found that the sum rule is fulfilled only in the case where the Dirac state contributions are included. 相似文献
11.
Based on QCD sum rule three-point and two-point external field formulas respectively, the vector vacuumsusceptibilities are calculated at the mean-field level in the framework of the global color symmetry model. It is shownthat the above two approaches of determination of the vector vacuum susceptibility may lead to different results. Thereason of this contradiction is discussed. 相似文献
12.
着重讨论了建立在相对论平均场基态上的相对论无规位相近似的自洽处理 .自洽处理要求基态和巨共振激发态的研究从同一个拉氏量出发,采用同一种建立在相对论下的完备基上的近似 .同时也讨论了自洽条件下Dirac海核子态的作用 ,指出 Dirac海核子态的贡献不能忽略 ,特别是在核的巨单极共振的情况.用约束的相对论平均场方法得到核的巨单极共振的能量逆权重的求和规则 ,从数值上验证了 Dirac海核子态的贡献. A consistent treatment is extremely important in relativistic approaches. We emphasized the consistent approach in relativistic random phase approximation built on relativistic mean filed ground states. The consistent treatment requires that the studies of the ground state and excited states of giant resonances are based on same effective Lagrangian, and on a same complete set of basis. It was found that the effect of the Dirac states could not be neglected, especially in the case of giant... 相似文献
13.
Using the light front wave functions of the scalar quark–diquark model for nucleon predicted by the soft-wall AdS/QCD, we calculate the flavor dependent gravitational form factors. We evaluate the matrix element of Pauli–Lubanski operator in this model and show that the intrinsic spin sum rule involves the higher twist form factor \({\bar{C}}\). The longitudinal momentum densities in the transverse impact parameter space are also discussed for both unpolarized and transversely polarized nucleons. 相似文献
14.
Renbao Liu 《量子光学学报》2006,12(B08):65-65
The two-pathway decay, spin-photon entanglement, and spontaneous generated spin coherence in a Lambdatype three-level system can be understood in a unified picture in terms of quantum entanglement of the electron spin, the photon polarization, and the photon waveform. Within such a unified picture, the spontaneous emission can be controlled to present a designated effect by external field, optical excitation, and quantum measurement. Various experiments are proposed to implement such control, with some of them already realized. 相似文献
15.
Based on QCD sum rule three-point and two-point external field formulas
respectively, the vector vacuum susceptibilities are calculated at the mean-field level in the
framework of the global color symmetry model. It is shown that the above two approaches
of determination of the vector vacuum susceptibility may lead to different results.
The reason of this contradiction is discussed. 相似文献
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In high energy scattering experiments, the proton spin is understood as the sum of the spin and orbital angular momentum of the quarks and gluons in Feynman’s parton picture. The Jaffe–Manohar form of the proton spin sum rule is justified as physical, and it is shown that the individual terms can be related to the proton matrix elements of certain quasi-obervables through a large momentum effective field theory. The relation is expressed as a factorization formula where the leading contribution to the quasi-observable is factorized into the parton observables and perturbative matching coefficients, and we present the results for the latter at one-loop order in perturbation theory. This will provide us with the basis to extract the proton spin content from the lattice QCD calculations of the quasi-observables. 相似文献
19.
We introduce a phenomenological QCD sum rule with an explicit diquark field. We investigate certain configurations of hadrons are expected to have a good diquark structure. The parameters of the model are a diquark mass ${(m_\phi)}$ and condensate ${(\langle \phi^2\rangle)}$ . Assuming that Λ baryons can be represented by a diquark and a spectator quark configuration, we find the sum rule works well for Λ, Λ c , and Λ b . We also find a duality relation between the mass and the condensate for which the parameter sets give good Borel curves. To maintain good Borel curve, a smaller diquark condensate is needed for an increased diquark mass. Using these parameter sets, we test the diquark structure in some hadrons which contain both good and bad diquark configurations. 相似文献
20.
The nucleon and its negative-parity excited states are examined in a maximum entropy method analysis of QCD sum rules. We derive the parity projected nucleon sum rules with all known first order α s corrections to the Wilson coefficients of the operator product expansion (OPE). As these corrections have turned out to be large, we suppress them by using a phase-rotated Gaussian kernel. This phase rotation strongly suppresses the continuum contribution and improves the convergence of the OPE. The resulting sum rule has the interesting feature that it is dominated by the term containing the chiral condensate of dimension 3. Analyzing this sum rule by the maximum entropy method, we are able to extract information of both the positive and negative parity states. 相似文献