Dynamical screening of AMM and QED effects for large-<Emphasis Type="Italic">Z</Emphasis> hydrogen-like atoms

The effective interaction ΔU_AMM of the anomalous magnetic moment (AMM) of an electron with the Coulomb field of an extended nucleus is analyzed. As soon as the q² dependence of the electron formfactor F₂(q²)is taken into account from the beginning, the AMM is found to be dynamically screened at small distances of r ? 1/m. The ΔU_AMM effects on the low-lying electronic levels of a superheavy extended nucleus with Zα > 1are analyzed using the nonperturbative approach. The growth rate of the ΔU_AMM contribution with increasing Z is shown to be essentially nonmonotonic. At the same time, the energy shifts of electronic levels in the vicinity of the threshold of the lower continuum monotonically decrease in the region Z ?Z_cr,1s. The latter result is generalized to the whole self-energy contribution to energy shifts of electronic levels, thus also referring to the possible behavior of QED radiative effects with virtual-photon exchange, considered beyond the framework of the perturbative expansion in Zα.     

Radiative corrections to the Lagrangian of the electromagnetic field

The single-loop corrections to the Lagrangian of a uniform, constant electromagnetic field are found which include the anomalous magnetic moment and electric dipole moment of the electron. The imaginary part of the effective Lagrangian, which determines the probability of electron-positron pair production is found. The asymptotic behavior of the effective action is studied for supercritical magnetic fields H » H₀ = m²/e with the dependence of the anomalous magnetic moment on H taken into account.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 37–42, March, 1987.     

Finite temperature effects in quantum field theory

We consider quantum electrodynamics at finite temperatures. By making use of the real time formalism we compute, on the one-loop level, the finite-temperature correction to the mass of the electron and to the anomalous magnetic moment a_e^th. The gauge-invariant correction to the electron mass is found to be a ten percent effect at a temperature of the order of 2×10¹⁰ K. Some astrophysical implications of this result are briefly discussed. The leading temperature correction to the anomalous magnetic moment of the electron is, at a temperature of 300 K, found to be one order of magnitude smaller than the τ-lepton contribution to a_e^th.     

The relaxation rate of the magnetic moment of a shallow acceptor center as a function of impurity concentration in silicon

A study is made into the temperature dependence of residual polarization of negative muons in crystalline silicon with the concentration of impurity of the n-and p-types ranging from 8.7×10¹³ to 4.1× 10¹⁸ cm^?3. The measurements are performed in a magnetic field of 1000 G transverse to the muon spin, in the temperature range from 4.2 to 300 K. The form of the temperature dependence of the relaxation rate v of the magnetic moment of the μAl⁰ acceptor in silicon is determined. For a nondegenerate semiconductor, the relaxation rate depends on temperature as v ∝ T ^q (q ≈ 3). A variation in the behavior of the temperature dependence and a multiple increase in the relaxation rate are observed in the range of impurity concentration in excess of 10¹⁸ cm^?3. The importance of phonon scattering and spin-exchange scattering of free charge carriers by an acceptor from the standpoint of relaxation of the acceptor magnetic moment is discussed. The constant of hyperfine interaction in an acceptor center formed by an atom of aluminum in silicon is estimated for the first time: |A _hf (Al)/2π| ～ 2.5×10⁶s^?1.     

Magnetoreflectance of the Γ6 – Γ8 exciton ground state in cubic ZnSe

Magnetoreflectance measurements on the ground state of the Γ₆ – Γ₈ free exciton in cubic ZnSe in magnetic fields up to 18 T are reported. The splitting between the |1, ±1〉 states was derived from the measured difference spectrum between σ⁺ and σ^--polarized reflectance in Faraday configuration. The splitting between the two states corresponding to |2, 0〉 and |1, 0〉 at B = 0 was determined by means of a lineshape analysis. We derive an electron g-factor g = 1.48 ± 0.25, in reasonable agreement with existing k · p calculations, and obtain an effective hole g-value $\text{K}\text{?}\text{= -0.26±0.06}$. In addition, we find an upper limit for the short range electron-hole spin exchange energy Δ ? 0.1 meV, which is considerably smaller than values, which is considerably smaller than values reported in the literature, but agrees with recent results on ZnTe obtained by uniaxial stress and also magnetoreflectance measurements.     

Towards Abelian-like formulation of the dual gluodynamics

We consider gluodynamics in case when both color and magnetic charges are present. We discuss first short distance physics, where only the fundamental |Q_m|=1 monopoles introduced via the 't Hooft loop can be considered consistently. We show that at short distances the external monopoles interact as pure Abelian objects. This result can be reproduced by a Zwanziger-type Lagrangian with an Abelian dual gluon and ordinary gluons in an adjoint representation. We introduce also an effective dual gluodynamics which might be a valid approximation at distances where the monopoles |Q_m|=2 can be considered as point-like as well. Assuming the monopole condensation we arrive at a model which is reminiscent in some respect of the Abelian Higgs model but, unlike the latter leaves space for the Casimir scaling.     

Electron resonance studies of the renner effect

The gas phase electron resonance spectra of NCO in its ground ²Π_3/2 vibronic state and in two excited vibronic states are described. Theoretical analysis of the spectra yields effective g values for the three states. In additon the ¹⁴N magnetic hyperfine and electric quadrupole coupling constants and the electric dipole moment are determined. The theory of the Renner coupling of electronic and vibrational motion is extended, and shown to account for anomalous contributions to the g values. The theory also shows that these contributions are closely related to the Renner coupling constant.     

Interaction of dirac particle AMM with Coulomb field of a superheavy nucleus: Perturbative and nonperturbative aspects

The interaction ΔU_AMM of the Dirac particle anomalous magnetic moment (AMM) with the Coulomb field of a nucleus and its effect on the low-lying atomic levels are studied for Zα > 1 using both perturbative and essentially nonperturbative approaches. The Zα dependence of particle wavefunctions (WFs) is fully taken into account from the beginning. In deriving the ΔU_AMM contribution, the nucleus is viewed either as a uniformly charged extended Coulomb source or as a distributed system formed by pointlike u and d quarks. When estimated nonperturbatively, the ΔU_AMM-induced effects in the Dirac equation framework prove to be identical for these two cases. At the same time, the ΔU_AMM-induced effect is specific in that its perturbative and nonperturbative estimates are very different for Δg ? const and practically identical as soon as the dynamical screening of AMM at short distances is taken into account in the Dirac equation.     

第Ⅰ种强度不对称三态叠加多模叠加态光场N次方Y压缩—第一正交相位分量的压缩情况

根据量子力学中的线性叠加原理,构造了由三个强度不等的多模相干态光场|{Z_j^(A)}>_q、|{Z_j^(B)}>_q和|{Z_j^(C)}>_q的线性叠加所组成的第Ⅰ种强度不对称三态叠加多模叠加态光场|ψ_l^(ABC)>_q.利用多模压缩态理论,研究了态|ψ_l^(ABC)>_q的第一正交方分量(即磁场分量)的广义非线性等幂次N次方Y压缩特性.结果发现:①在上述各多模相干态光场中各模的强度和各模的初始相位各不相等的情况下,态|ψ_l^(ABC)>_q的第一正交分量-磁场分量在一定的条件下,总可呈现出周期性变化的、任意等幂次的N次方Y压缩效应;②当上述各多模相干态光场的强度和各模的初始相位相等时,态|ψ_l^(ABC)>_q的磁场分量的N次方Y压缩现象消失,态|ψ_l^(ABC)>_q可恒处于等幂次N-Y最小测不准态.     

Hopping conductivity and weak localization in two-dimensional disordered systems

The low temperature dependence of hopping conductivity σ(T) in 2d-DS with weak localization of electron states is investigated. Hopping between neighbouring localized states is suggested and a power law for σ(T) is obtained. Coulomb effects are shown to be negligible for this process. The transition from the logarithmic T dependence and to the exponential Mott's law is discussed. The density distribution of localized electron states is proved to be exponential. The dielectric permeability ?′(ω) is found to be proportional to |ω|^?1 in the field of validity of the logarithmic corrections.     

第Ⅰ类多模叠加态|ψ1(3)〉q中广义磁场的高次和压缩

构造了由多模相干态|{Z_j} > _q、多模真空态|{O_j} >_q和多模相干态的相反态|{-Z_j} > _q三者的线性叠加所组成的第Ⅰ类三态叠加多模叠加态光场|ψ₁⁽³⁾ > _q,利用多模压缩态理论,研究了态|ψ₁⁽³⁾ > _q中广义磁场分量的等幂次高次和压缩效应.结果发现:态|ψ₁⁽³⁾ > _q是一种典型的三态叠加多模非经典光场;当各模的初始相位和 满足一定的取值条件、并且态|ψ₁⁽³⁾〉_q中任意两态的态间初始相位差(θ_pq^(R)-θ_0q⁽⁰⁾)、(θ_nq^(R)-θ_0q⁽⁰⁾)和(θ_pq^(R)-θ_nq^(R))等分别在各自的闭区间内连续变化时,则态|ψ₁⁽³⁾ > _q的广义磁场分量(即第一正交相位分量)总可分别呈现出周期性变化的、等幂次的奇数模-偶数次、偶数模-奇数次、偶数模-偶数次或者奇数模-奇数次的高次和压缩效应.     

The temperature dependence of the hyperfine interaction of the transition metal osmium in a gadolinium host matrix

Integral perturbed angular correlations of the 931-155keVγγ-cascade of¹⁸⁸Os in Gd have been measured. With this technique the combined magnetic and electric hyperfine interaction of the 155 keV level of¹⁸⁸Os as an impurity in a Gd host has been studied as a function of temperature. The result for the electric field gradient of Os in Gd at 300 K is: $$\left| {V_{zz} \left( {Os:\underline {Gd} } \right)} \right| = \left( {12.8_{ - 1.9}^{ + 3.1} } \right) \cdot 10^{17} {V \mathord{\left/ {\vphantom {V {cm^2 }}} \right. \kern-\nulldelimiterspace} {cm^2 }}.$$ For the magnetic hyperfine field at 4.2 K the value $$H_{hf} \left( {Os:\underline {Gd} } \right) = - 134\left( {26} \right)kG$$ was obtained. Sign and magnitude of the magnetic hyperfine field suggest the existence of a localized moment of about ?0.4 µ _B at the site of Os in Gd. With increasing temperature the magnetic hyperfine field decreases much stronger than the magnetization of the host. Possible explanations for this anomalous temperature dependence are discussed.     

Perturbative fragmentation of a vector color particle into bound states involving a heavy antiquark

Vector-particle fragmentation into possible S-wave bound states involving a heavy antiquark is considered for high-energy processes at high transverse momenta, and the relevant fragmentation function is calculated in the leading order of perturbative QCD for various patterns of the anomalous magnetic moment. One-loop equations describing the q ² evolution of the fragmentation-function moments that is caused by hard-gluon emission from the vector particle are derived. The integrated probabilities of fragmentation are obtained. The distribution of the bound state in the transverse momentum defined with respect to the fragmentation axis is calculated in the scaling limit.     

High Z effects in accounting for radiative component of the electron magnetic moment in hydrogen-like atoms

The behavior of electron energy levels in hydrogen-like atoms is studied while taking into account the nonperturbative interaction between the radiative component of the magnetic moment of a free electron Δg _free and the Coulomb field of an atomic nucleus with charge Z, including those with Z > 137. It is shown that for Zα ? 1 the energy-level shift is rather effectively determined through the matrix elements of the corresponding Dirac-Pauli operator with relativistic Coulomb wave functions. At the same time, for superheavy nuclei with Z ～ 170, this shift, generated by Δg _free, is genuinely nonperturbative, behaves like ～Z ⁵ near the threshold of negative continuum, exceeds all the estimates of radiative corrections coming from vacuum polarization and electron self-energy known so far, and turns out to be at least of the same order as the effects of nuclear charge screening by filled electron shells.     

态|ψ5(3)〉q中广义电场的2(2m+1)次方Y压缩特性

利用多模压缩态理论,研究了由多模复共轭相干态|{Z_j^*}〉_q(j =1,2,3,…,…,q)、多模复共轭相干态的相反态|{-Z_j^*}〉_q和多模虚相干态|{iZ_{j}〉q的线性叠加所组成的第Ⅴ类三态叠加多模叠加态光场|ψ5⁽³⁾〉q中广义电场分量的等幂次N次方Y压缩特性 .结果发现 :当压缩次数N=2 p且p=2m+1(m=0,1,2,…,…)时,在一定的条件下,态|ψ5⁽³⁾〉q的广义电场分量(即第二正交相位分量)可呈现出周期性变化的、偶数次的等幂次2(2m+1)次方Y压缩效应 .}     

Damping of zero sound in Luttinger liquids

We calculate the damping γ_q of collective density oscillations (zero sound) in a one-dimensional Fermi gas with dimensionless forward scattering interaction F and quadratic energy dispersion k² / 2 m at zero temperature. Using standard many-body perturbation theory, we obtain γ_q from the expansion of the inverse irreducible polarization to first order in the effective screened (RPA) interaction. For wave-vectors | q| /k_F ≪F (where k_F = m v_F is the Fermi wave-vector) we find to leading order γ_q ∝| q |³ /(v_F m²). On the other hand, for F ≪| q| /k_F most of the spectral weight is carried by the particle-hole continuum, which is distributed over a frequency interval of the order of q²/m. We also show that zero sound damping leads to a finite maximum proportional to |k - k_F | ^{-2 + 2 η} of the charge peak in the single-particle spectral function, where η is the anomalous dimension. Our prediction agrees with photoemission data for the blue bronze K_0.3MoO₃. We comment on other recent calculations of γ_q.     

态|Ψ(3)>q中广义电场分量的偶数次N次方Y压缩

构造了由多模复共轭虚相干态、多模复共轭虚相干态的相反态和多模复共轭相干态的线性叠加所组成的一种新型的三态叠加多模叠加态光场|Ψ⁽³⁾>_q.利用多模压缩态理论,研究了态|Ψ⁽³⁾>_q中广义电场分量的偶数次等幂次N次方Y压缩特性.结果发现:态|Ψ⁽³⁾>_q是一种典型的三态叠加多模非经典光场;当压缩次数N等于2P且P为2m’+1(m’=0,1,2,…,…)时,如果各模的初始相位φ_j(j=1,2,3,…,…,q)、态间的初始相位差(θ₁-θ₂)、(θ₁-θ₃)和(θ₂-θ₃),以及各单模相干态光场的总的平均光子数等分别满足各自的取值条件,则在这种情况下态|Ψ⁽³⁾>_q的广义电场分量可呈现出偶数次的广义非线性等幂次2(2m’+1)次方Y压缩效应.     

一种新型的两态叠加多模叠加态光场的广义非线性等阶N次方Y压缩

本文根据量子力学中的线性叠加原理,构造了由多模(即q模)相干态的相反态|{-Z_j}〉_q及多模虚相干态的相反态|{-iZ_j}〉_q这两者的线性叠加所组成的一种新型的两态叠加多模叠加态光场|ψ_msc⁽²⁾〉_q.利用新近建立的多模辐射场的广义非线性等阶高阶压缩理论,研究了态|ψ_msc⁽²⁾〉_q的广义非线性等阶N次方Y压缩特性.结果发现,1)当压缩阶数N=2P且P=2m(m=1,2,3,…,…)时,态|ψ_msc⁽²⁾〉_q恒处于N-Y最小测不准态;2)当N=2P且P=2m’+1(m’=0,1,2,…,…)时,如果各模的初始相位φ_j、态间的初始相位差与各单模相干态光场的平均光子数之和∑_j=1^qR_j²即[(θ_pq^(R)-θ_nq^(I))-∑_j=1^qR_j²]满足一定的量子化条件,态|ψ_msc⁽²⁾〉_q可呈现周期性变化的、任意阶的等阶N次方Y压缩效应;3)当N为奇数时,态|ψ_msc⁽²⁾〉_q在一定条件下恒处于N-Y测不准态;4)态|ψ_msc⁽²⁾〉_q与文献21中的态|ψ⁽²⁾〉_q出现部分压缩简并现象,从而更进一步表明压缩简并现象的存在是有某种客观内在联系的.     

Enhancement of the anomalous Hall effect and spin glass behavior in the bilayered manganite La2−2xSr1+2xMn2O7

The Hall resistivity and magnetization have been investigated in the ferromagnetic state of the bilayered manganite La_2−2xSr_1+2xMn₂O₇ (x=0.36). The Hall resistivity shows an increase in both the ordinary and anomalous Hall coefficients at low temperatures below 50 K, a region in which experimental evidence for the spin glass state has been found in a low magnetic field of 1 mT. The origin of the anomalous behavior of the Hall resistivity relevant to magnetic states may lie in the intrinsic microscopic inhomogeneity in a quasi-two-dimensional electron system.