Bifurcation in Rotational Spectra of Nonlinear AB2_2 Molecules

A classical microscopic theory of rovibrational motion at high angular momenta in symmetrical non-linear molecules AB$_2$ is derived within the framework of small oscillations near the stationary states of a rotating molecule. The full-dimensional analysis including stretching vibrations has confirmed the existence of the bifurcation predicted previously by means of the rigid-bender model. The formation of fourfold energy clusters has already been experimentally verified for H$_2$Se and it has been demonstrated in fully-dimensional quantum mechanical calculations using the MORBID computer program. We show in the present work that apart from the level clustering, the bifurcation produces physically important effects including molecular symmetry-breaking and a transition from the normal mode to the local mode limit for the stretching vibrations due to rovibrational interaction. The application of the present theory with realistic molecular potentials to the H$_2$Te, H$_2$Se and H$_2$S hydrides results in predictions of the bifurcation points very close to those calculated previously. However for the lighter H$_2$O molecule we find that the bifurcation occurs at higher values of the total angular momentum than obtained in previous estimations. The present work shows it to be very unlikely that the bifurcation in H$_2$O will lead to clustering of energy levels. This result is in agreement with recent variational calculations.Comment: latex, 19 pages including 2 figures provided as *.uu fil

Implications of N=4 superconformal symmetry in three spacetime dimensions

We study implications of N=4 superconformal symmetry in three dimensions, thus extending our earlier results in arXiv:1503.04961 devoted to the N=1,2,3 cases. We show that the three-point function of the supercurrent in N=4 superconformal field theories contains two linearly independent forms. However, only one of these structures contributes to the three-point function of the energy-momentum tensor and the other one is present in those N=4 superconformal theories which are not invariant under the mirror map. We point out that general N=4 superconformal field theories admit two inequivalent flavour current multiplets and show that the three-point function of each of them is determined by one tensor structure. As an example, we compute the two- and three-point functions of the conserved currents in N=4 superconformal models of free hypermultiplets. We also derive the universal relations between the coefficients appearing in the two- and three-point correlators of the supercurrent and flavour current multiplets in all superconformal theories with N=1,2,3,4 supersymmetry. Our derivation is based on the use of Ward identities in conjunction with superspace reduction techniques.Comment: 75 page

Superconformal field theory in three dimensions: Correlation functions of conserved currents

For N-extended superconformal field theories in three spacetime dimensions (3D), with N=1,2,3, we compute the two- and three-point correlation functions of the supercurrent and the flavour current multiplets. We demonstrate that supersymmetry imposes additional restrictions on the correlators of conserved currents as compared with the non-supersymmetric case studied by Osborn and Petkou in hep-th/9307010. It is shown that the three-point function of the supercurrent is determined by a single functional form consistent with the conservation equation and all the symmetry properties. Similarly, the three-point function of the flavour current multiplets is also determined by a single functional form in the N=1 and N=3 cases. The specific feature of the N=2 case is that two independent structures are allowed for the three-point function of flavour current multiplets, but only one of them contributes to the three-point function of the conserved currents contained in these multiplets. Since the supergravity and super-Yang-Mills Ward identities are expected to relate the coefficients of the two- and three-point functions under consideration, the results obtained for 3D superconformal field theory are analogous to those in 2D conformal field theory. In addition, we present a new supertwistor construction for compactified Minkowski superspace. It is suitable for developing superconformal field theory on 3D spacetimes other than Minkowski space, such as S^1 x S^2 and its universal covering space R x S^2.Comment: 81 pages; v2: reference added, typos correcte

Investigation of Photoelectric Converters with a Base Cadmium Telluride Layer with a Decrease in Its Thickness for Tandem and Two-sided Sensitive Instrument Structures

Photovoltaic cells with a base layer of cadmium telluride with a decrease in its thickness are studied. It is known that the widespread use of photovoltaic converters is constrained by their high price in the case of highly efficient instrument structures, or low efficiency. The creation of tandem and two-sided sensitive photoelectric converters will reduce their cost while increasing their efficiency. However, to create tandem and two-sided sensitive photoelectric converters, the necessary conditions are the use of transparent contacts and a decrease in the thickness of the base layer for efficient absorption of incident radiation by the converter, which is lower. In the research process, it was found that reducing the thickness of the base layer to 1 μm allows to increase the efficiency of the photoelectric transducer during irradiation from the back. An increase in the efficiency of the photoelectric converter occurs due to a decrease in the distance from the generation region of nonequilibrium charge carriers in the region of separation. If the thickness of the base layer is less than 1 μm, then regardless of which side of the irradiation is carried out, a decrease in the efficiency of the instrument structure is observed. Increase in the efficiency of photoconverters is associated with an increase in the negative influence of recombination processes on the back contact, a decrease in the number of charge carriers generated due to incomplete absorption of incident radiation, and a decrease in the volume of the built-in field of the separating barrier when it overlaps with the depletion region of the back contact. ITO/CdS/CdTe/Cu/ITO SCs with a base layer thickness of 1 μm demonstrates degradation stability. The highest value of efficiency in the case of illumination from the front side 8.1 % and with illumination from the back side 3.8 % received after a year of operation of the photovoltaic converter

Spacetime Brout-Englert-Higgs effect in General Relativity interacting with p-brane matter

We review the manifestation of the Brout-Englert-Higgs effect in general relativity interacting with point-like and extended objects (p-branes including string for p=1 and membrane for p=2), which manifests itself in the appearance of the brane source in the Einstein equation while the graviton remains massless (hep-th/0112207, hep-th/0507197 and refs therein), and discuss briefly its relation and differences with the model for massive spin 2 field proposed recently by G. t'Hooft in [arXiv:0708.3184 [hep-th]].Comment: LaTeX, jpconf class, 5 pages. Contribution to the Procs. of the ERE2009 Meeting, Bilbao, September 200

Paramagnonlike excitations and spin diffusion in magnetic resonance studies of copper oxide superconductors

The relaxation function theory for a doped two-dimensional Heisenberg antiferromagnetic system in the paramagnetic state for all wave vectors through the Brillouin zone is presented in view of low frequency response of high-$T_c$ copper oxide superconductors. We deduced the regions of long lifetime [$T \lesssim 400(1-4x)$ K] and "overdamped" [$T \gtrsim 700(1-4x)$ K] paramagnonlike excitations in the temperature ($T$)-doping index ($x$) phase diagram from plane oxygen nuclear spin-lattice relaxation rate $^{17}(1/T_1)$ data in up to optimally doped La$_{2-x}$Sr$_{x}$CuO$_{4}$ thus providing the regimes for the spin wave concept and the ''overdamped'' mode.Comment: Physical Review B, accepted, in pres

Impurity Scattering in Luttinger Liquid with Electron-Phonon Coupling

We study the influence of electron-phonon coupling on electron transport through a Luttinger liquid with an embedded weak scatterer or weak link. We derive the renormalization group (RG) equations which indicate that the directions of RG flows can change upon varying either the relative strength of the electron-electron and electron-phonon coupling or the ratio of Fermi to sound velocities. This results in the rich phase diagram with up to three fixed points: an unstable one with a finite value of conductance and two stable ones, corresponding to an ideal metal or insulator.Comment: 4 pages, 2 figure

Jumps in current-voltage characteristics in disordered films

We argue that giant jumps of current at finite voltages observed in disordered samples of InO, TiN and YSi manifest a bistability caused by the overheating of electrons. One of the stable states is overheated and thus low-resistive, while the other, high-resistive state is heated much less by the same voltage. The bistability occurs provided that cooling of electrons is inefficient and the temperature dependence of the equilibrium resistance, R(T), is steep enough. We use experimental R(T) and assume phonon mechanism of the cooling taking into account its strong suppression by disorder. Our description of details of the I-V characteristics does not involve adjustable parameters and turns out to be in a quantitative agreement with the experiments. We propose experiments for more direct checks of this physical picture.Comment: Final version, as published; 4 pages, 3 figure