A note on spin-flip electric dipole transitions

Inelastic scattering 22MeV proton from²³⁸U has been studied. Angular distributions of the states of the rotational band have been measured. Coupled-channel analysis allows determination of the deformation parametersβ ₂,β ₄ andβ ₆. These values are somewhat in disagreement with other experimental results.     

Isotopic selection using nuclear spin induced electric dipole transitions

The nuclear spin induced electric dipole transitions $\text{6p}{}^2\text{(}\text{1}\text{2}\text{,}\text{1}\text{2}{}_0\text{?6p}\text{n}\text{s(}\text{1}\text{2}\text{,}\text{1}\text{2}\text{)}{}^0{}_0$ and $\text{6p}{}^2\text{(}\text{1}\text{2}\text{,}\text{1}\text{2}\text{)}{}_0\text{?6p}\text{n}\text{d}\text{1}\text{2}\text{[}\text{3}\text{2}\text{]}{}^0{}_2$ in ²⁰⁷Pb have been observed in the vacuum ultraviolet absorption spectrum of lead. Utilization of such transitions as a step in the laser isotope separation of ²⁰⁷Pb has the advantage that the selective pumping step involves levels which are separated by the relatively large fine structure spacing rather than the relatively small electronic isotopic and/or hyperfine spacings. The possibility of the separation of other odd mass numbered isotopes in the sixth and seventh periods by similar techniques is discussed briefly.     

Probabilities of radiative dipole transitions of parahelium in an electric field

Quadratic Stark corrections to the wave functions, matrix elements, and probabilities of transitions between the singlet states ¹ S ₀ and ¹ P ₁ of helium atoms are calculated. The coefficients of the polynomials that depend on the effective principal quantum number of the upper level v _f and that approximate the numerical values of the polarizabilities, the quadratic corrections to the wave functions, and the probabilities of transitions to highly excited Rydberg states with large v _f are determined. The results of calculations testify that the probabilities of all σ transitions n _i ¹ S ₀ → n _f ¹ P ₁ and π transitions to the states with n _f > n _i /2 are decreased with increasing electric field strength, except for the transition 2¹ S ₀ → 2¹ P ₁, whose probability increases both for σ and for π transitions.     

Investigation of anomalousK,L andM shell conversion in electric dipole transitions

Anomalous experimental conversion coefficients of theK, L andM subshells are investigated for thirteen highly hindered electric dipole transition in six deformed odd mass nuclei. For a distinct nuclear transition, all experimental anomalies are consistent with one parameter, containing all nuclear information. The values of this parameter are determined and a simple connection with the hindrance of the transition seems to exist. TheK andL shell conversion coefficients have been recalculated, while theM shell conversion data were newly computed including all finite nuclear size effects as well as screening by a Thomas-Fermi-Dirac model.     

The neutron electric dipole moment in the cloudy bag model

An evaluation of the neutron electric dipole moment (NEDM), using the cloudy bag model (CBM) shows that two CP-violating effects (a quark mass term and a pion-quark interaction) have contributions that are about equal in magnitude, but opposite in sign. This cancellation allows the upper limit on the θ parameter to increase by about an order of magnitude.     

The neutron electric dipole moment in the standard KM model

We compute the electric dipole moment of the neutron in the standard KM model, including the meson-baryon intermediate states which dominate the result in the SU(3) × SU(3) chiral limit, and find 1.4×10⁻³¹ e cm⩾|D_n|⩾9.9×10⁻³³ e cm.     

Probabilities of electric dipole transitions in the spectra of ions of the erbium isoelectronic sequence

The probabilities of the 4f ¹³6p→4f ¹³ ns (n=6 and 7) electric dipole transitions are calculated for the spectra of YbIII, LuIV, and HfV ions of the erbium isoelectronic sequence. The wave functions of the intermediate coupling scheme, which are necessary for calculating the relative line strengths, are semiempirically obtained from experimentally measured energy intervals between the fine-structure levels. To pass to the absolute values, radial integrals of transitions are used, which are evaluated with the Hartree-Fock functions.     

The linked dipole chain model for DIS

The Linked Dipole Chain Model provides an interpolation between the regions of high Q² (DGLAP) and low x moderate Q² (BFKL) in DIS. It is a reformulation and a generalization of the results obtained by Ciafaloni, Catani, Fiorani and Marchesini, and it gives a unified treatment of “normal DIS”, boson-gluon fusion events and hard subcollisions in resolved photon-proton scattering. Thus the formalism provides a complete picture which incorporates all hard or semihard hadronic interactions in a simple way, which is suitable for a Monte Carlo treatment of both structure functions and final state properties. We also discuss non-leading effects which significantly reduce the increase of the structure function for very small x-values.     

The electric dipole moment of the neutron in the Kobayashi-Maskawa model

A possible mechanism for producing a neutron electric dipole moment to order G_F² in the Kobayashi-Maskawa model is proposed; the consequent order of magnitude of the dipole moment would be 10^?30 cm in units of the electric charge.     

Magnetic and electric phase transitions in the Hubbard model

Within the Hubbard model, two boson Green’s functions that describe the propagation of collective excitations of the electronic system—magnons (states with a single electron spin flip) and doublons (states with two electrons at one site of the crystal lattice)—are calculated for a Coulomb interaction of arbitrary strength and for an arbitrary electron concentration by applying a decoupling procedure to the double-time X-operator Green’s functions. It is found that the magnon and doublon Green’s functions are similar in structure and there is a close analogy between them. Instability of the paramagnetic phase with respect to spin ordering is investigated using the magnon Green’s function, and instability of the metallic phase to charge ordering is analyzed with the help of the doublon Green’s function. Criteria for the paramagnet-ferromagnet and metal-insulator phase transitions are found.     

Inner conversion process of electric dipole transitions in180Hf and182W

The conversion electron process of the retarded electric dipole transitions of 58keV in¹⁸⁰Hf and 67, 116, 152, 156 and 222 keV in¹⁸²W have been studied by means of high resolution double focusing beta-ray spectrometers. No penetration effects were found in the conversion process of the retarded 58 keV and 67, 116 and 222 keV E1 transitions. While the retarded 152 and 156 keV transitions in¹⁸²W show an anomalous internal conversion ratios compared with theoretical values. Implications of the results for current nuclear theories are discussed.     

The neutron electric dipole moment in the standard model with four generations

We calculate the neutron electric dipole moment in the standard model with four generations. In the most favourable case, our result, 2.4×10⁻³²e cm, is larger than the three-generation result by a factor of 20.     

A model for a large electric dipole moment of the neutron

It is shown that a mixing of ordinary quarks and mirror quarks could induce a large electric dipole moment, d_n, for the neutron. For an about 1% mixing the prediction is |d_n| ≅ 10⁻²⁵ e cm. Recent results of two experimental groups, one at the Leningrad Nuclear Physics Institute and the other at the Institute Laue-Langevin, Grenoble, indicate that the dipole moment may have such a high value.     

Electric dipole transitions in neutron-rich nuclei

The structure of neutron-rich nuclei in several isotopes is investigated by shell model calculations. We study the electric dipole (E1) transitions in C isotopes focusing on the interplay between the low-energy Pigmy strength and the giant dipole resonance (GDR). Reasonable agreement is obtained with available experimental data for the photoreaction cross sections in ¹²C, ¹³C, and ¹⁴C with the inclusion of the quenching effects. A low-energy peak in the dipole strength in ¹⁵C is associated with a single-particle motion of the 1s_1/2 valence neutron relative to the ¹⁴C core. The calculated transition strength below the GDR in C isotopes heavier than ¹⁵C is found to exhaust about 50–80% of the cluster sum rule value and 12–16% of the classical Thomas-Reiche-Kuhn sum rule value. Next, we point out that the quadrupole and magnetic moments in the odd C isotopes strongly depend on configuration, which will be useful to determine the spin parities and the deformations of the ground states of these nuclei. The electric quadrupole (E2) transitions in even C isotopes are also studied. The isotopic dependence of the E2 transition strength is found to be reasonably well explained, although the calculated strength largely overestimates the unexpectedly small strength observed in ¹⁶C. The E1 strength in ¹⁸N and ¹⁹N as well as in Ne isotopes is also investigated.     

Effect of metallic and hyperbolic metamaterial surfaces on electric and magnetic dipole emission transitions

Spontaneous emission patterns of electric and magnetic dipoles on different metallic surfaces and a hyperbolic metamaterial (HMM) surface were simulated using the dyadic Green’s function technique. The theoretical approach was verified by experimental results obtained by measuring angular-dependent emission spectra of europium ions on top of different films. The results show the modified behavior of electric and magnetic dipoles on metallic and HMM surfaces. The results of numerical calculations agree well with experimental data.