A frustrated heisenberg antiferromagnet on a triangular lattice with next-nearest neighbor interactions

Using the Monte Carlo method, we study the critical properties of the three-dimensional frustrated Heisenberg model on a triangular lattice with allowance for next-nearest neighbor interactions. Using the theory of finite-size scaling, we calculate the static magnetic and chiral critical exponents of heat capacity α, susceptibility γ, γ _k , magnetization β, β _k , and correlation length ν.     

Monte Carlo investigation of phase transitions in the frustrated Heisenberg model on a triangular lattice

The critical properties and phase transitions of the three-dimensional frustrated antiferromagnetic Heisenberg model on a triangular lattice have been investigated using the Monte Carlo method with a replica algorithm. The critical temperature has been determined and the character of the phase transitions has been analyzed using the method of fourth-order Binder cumulants. A second-order phase transition has been found in the three-dimensional frustrated Heisenberg model on a triangular lattice. The static magnetic and chiral critical exponents of the heat capacity α, the susceptibility γ and γ _k , the magnetization β and β _k , the correlation length ν and ν _k , as well as the Fisher exponents η and η _k , have been calculated in terms of the finite-size scaling theory. It has been demonstrated that the three-dimensional frustrated antiferromagnetic Heisenberg model on a triangular lattice forms a new universality class of the critical behavior.     

Connectivity of growing networks with link constraints

We propose a growing network model with link constraint, in which new nodes are continuously introduced into the system and immediately connected to preexisting nodes, and any arbitrary node cannot receive new links when it reaches a maximum number of links k_m. The connectivity of the network model is then investigated by means of the rate equation approach. For the connection kernel A(k)=k^γ, the degree distribution n_k takes a power law if γ≥1 and decays stretched exponentially if 0≤γ< 1. We also consider a network system with the connection kernel A(k)=k^α(k_m-k)^β. It is found that n_k approaches a power law in the α> 1 case and has a stretched exponential decay in the 0≤α< 1 case, while it can take a power law with exponential truncation in the special α=β=1 case. Moreover, n_k may have a U-type structure if α> β.     

Entanglement and Mixedness of Locally Cloned Non-Maximal W-State

In this work we describe a protocol by which two of three parties generate two bipartite entangled state among themselves without involving third party, from a non maximal W-state or W-type state |X〉=α|001〉₁₂₃+β|010〉₁₂₃+γ|100〉₁₂₃,α ²+β ²+γ ²=1 shared by three distant partners. Also we have considered the case β=γ, to obtain a range for α ², for which the local output states are separable and non local output states are inseparable. We also find out the dependence of the mixedness of inseparable states with their amount of inseparability, for that range of α ².     

Properties of integral least squares method

A new modification of the least squares method (LSM) is proposed. The main idea is to consider the fitting parameters β _i as independent random variables with a certain distribution density F(β₁, β₂, ..., β _k ; φ₁, ..., φ _m ), which depends on a set of m experimental points φ _j . Within this approach, the estimates of the parameters minimize squared deviations and are equivalent to means of the probability distribution = = ∫β _i F(β₁, β₂, ..., β _k ; φ₁, ..., φ _m )dβ₁ dβ₂...dβ _k . Original Russian Text ? I.D. Gorlachev, B.B. Knyazev, A. Kuketayev, F.M. Pen’kov, 2009, published in Izvestiya Rossiiskoi Akademii Nauk. Seriya Fizicheskaya, 2009, Vol. 73, No. 2, pp. 257–260.     

Structure of turbulent flows of incompressible fluids and the parametrization of turbulence

The structure of stationary isotropic, homogeneous turbulence in an incompressible fluid with Re ≫ 1 set into motion by a force with amplitude f ₀ and spatial and temporal time scales of r ₀ and τ ₀, respectively, is examined. It is found that, depending on the magnitude of the force that sets the fluid into motion, three fundamentally different turbulent stationary states of the fluid can develop and the dimensionless parameters responsible for transitions from one state to another, γ=f ₀ τ ₀ ² /r ₀ and Γ=γ ^4/3 Re, are determined. It is shown that for γ≪1 and Γ≪1 a Kolmogorov spectrum with E(k)∝1/k ^5/3 develops in the inertial range. During the transition to turbulent flows driven by large amplitude forces f ₀, i.e., during the transition to a regime with γ≪1 and Γ ≫ 1, a segment of the spectrum with E(k)∝1/k ² develops near the viscous range and “detaches” the Kolmogorov spectrum from the viscous range. Further increases in the amplitude f ₀ of the force, i.e., approaching the parameter range with γ≫1 and Γ≫1, causes the entire inertial range to be “occupied” by a spectrum E(k)∝1/k ², and outside the inertial range, large scale structures with a characteristic size extending to γ ^2/5 r ₀ begin to be generated. In the regime with Γ≪1, the power dissipated per unit mass of fluid is independent of the viscosity, but on going to turbulent regimes with Γ≫1, the viscous losses begin to depend on the viscosity of the fluid. The “turn-off” of viscous dissipation for Γ≫1 shows that a drag crisis can occur simply as the source power is increased, without any further conditions. With this method for the excitation of turbulence, the Loitsyanskii integral diverges for arbitrary values of γ and Γ. A physical mechanism is proposed to explain the readjustment of the spectrum of the turbulent fluctuations at different γ and Γ. These results have all been obtained neglecting intermittency. Zh. éksp. Teor. Fiz. 116, 1630–1647 (November 1999)     

Ionic conductivity and structural properties of MnO-doped Bi4V2O11 system

Bi₄V₂O₁₁ exists in three phases viz. α, β, and γ. High temperature γ-phase can be stabilized to room temperature owing to its higher conductivity by the partial substitution of metallic cations for vanadium in Bi₄V₂O₁₁. Phase transitions from α → β and β → γ are composition and temperature-dependent. Mn²⁺-doped compounds Bi₄V_2−x Mn _x O_{11− δ} (0 ≤ x ≤ 0.4) have been synthesized by solid state reaction technique and investigated by X-ray diffraction and ionic conductivity measurement. High ionic conducting γ-phase is stabilized for x ≥ 0.2. The ionic conductivity of the series of Bi₄V_2−x Mn _x O_{11− δ} samples has been measured by using ac impedance spectroscopy technique. The conductivity data do show departure from its simple Arrhenius behavior for all of the compositions. The highest conductivity observed for x = 0.2 sample can be attributed to lower activation energy.     

Study of the N = 50 major shell effect toward 78Ni at PARRNe⋆

The γ-ray de-excitations following the β-decay of ⁸³Ga and the β-n decay of ⁸⁴Ga have been studied. The radioactive species were produced using the PARRNe on-line mass-separator installed at the IPN Orsay Tandem accelerator. Two γ-lines were attributed to ⁸³Ge with the aid of β-γ and γ-γ coincidences. The Z identification of the γ-lines was provided by time analysis of a buid-up/decay cycle. The excited levels of ⁸³Ge can be explained by the coupling of the single neutron state ν2d _5/2 to the first 2⁺ excitation of the ⁸²Ge core.     

L X-ray energy shifts and intensity ratios in tantalum with C and N ions — multiple vacancies in M, N and O shells

The energy shifts and intensity ratios of different L X-ray components in tantalum element due to 10 MeV carbon and 12 MeV nitrogen ions are estimated. From the observed energy shifts, the possible number of simultaneous vacancies in M shell are estimated. A comparison of L _α /L _β2.15, L _β1/L _γ1 and L _γ2.3/L _γ4.4 with the ratios due to Scofield theoretical transition rates indicate that the number of multiple vacancies in N shell are higher than the vacancies in M and O shell. Employing Larkin’s statistical scaling procedure, the number of possible multiple vacancies in N and O shells are estimated quantitatively.     

Intrinsic frame inverse mass tensor as a function of <Emphasis Type="Italic">β</Emphasis> and <Emphasis Type="Italic">γ</Emphasis> in the Bohr Hamiltonian

Analytical expressions are derived for the components of the intrinsic frame inverse mass tensor of the Bohr Hamiltonian. These expressions contain parameters which are determined by the experimental data on the B(E2)’s and the excitation energies of the low-lying collective states. It is shown that the nondiagonal component of the intrinsic frame mass tensor has a small effect on the collective motion. It is shown also that the values of the B _ββ , B _γγ and the rotational mass coefficientB ₁ differ in the well-deformed nuclei by factor 3 or more.     

Phase transitions in the framework of complete version of IMB-1

The classical energy functional of complete IBM-1 model version is studied in terms of nuclear shape variables (β, γ), employing two essential control parameters (r ₂, r ₁) used in catastrophe theory formalism. The dependence of energy surface equilibrium values from deformation parameter β is analyzed in the case when γ = 0. The results, obtained for critical points and phase transition lines between spherical (β = 0) and two deformed (β > 0, β < 0) shapes, are compared with the ones, following from the studies, in which the simplified extended Casten triangle version of interacting boson model was used. Original Russian Text ? J. Proskurins, A. Andrejevs, T. Krasta, J. Tambergs, 2009, published in Izvestiya Rossiiskoi Akademii Nauk. Seriya Fizicheskaya, 2009, Vol. 73, No. 2, pp. 241–244. The article is published in the original.     

Universality of the REM for Dynamics of Mean-Field Spin Glasses

We consider a version of Glauber dynamics for a p-spin Sherrington– Kirkpatrick model of a spin glass that can be seen as a time change of simple random walk on the N-dimensional hypercube. We show that, for all p ≥ 3 and all inverse temperatures β > 0, there exists a constant γ _{β ,p}  > 0, such that for all exponential time scales, exp(γ N), with γ < γ _{β ,p} , the properly rescaled clock process (time-change process) converges to an α-stable subordinator where α = γ/β ² < 1. Moreover, the dynamics exhibits aging at these time scales with a time-time correlation function converging to the arcsine law of this α-stable subordinator. In other words, up to rescaling, on these time scales (that are shorter than the equilibration time of the system) the dynamics of p-spin models ages in the same way as the REM, and by extension Bouchaud’s REM-like trap model, confirming the latter as a universal aging mechanism for a wide range of systems. The SK model (the case p = 2) seems to belong to a different universality class.     

New data for the 197Au(γ, nX) and 197Au(γ, 2nX) reaction cross sections

The results from experimental and theoretical studies of the total and partial cross sections of photoneutron reactions on the ¹⁹⁷Au isotope were analyzed. The cross sections for reactions σ(γ, nX) = σ(γ, n) + σ(γ, np) + … + σ(γ, 2nX) = σ(γ, 2n) + σ(γ, 2np) + … were evaluated in the energy range 7 ≤ E _γ ≤ 30 MeV using an approach free of the shortcomings of experimental photoneutron multiplicity sorting methods. The total photoneutron reaction cross sections σ^exp(γ, xn) = σ^exp(γ, nX) + 2σ^exp(γ, 2nX) + … = σ^exp(γ, n) + σ^exp(γ, np) + 2σ^exp(γ, 2n) + 2σ^exp(γ, 2np) + … were used as the initial experimental data. The contributions from the cross sections σ(γ, nX) and σ(γ, 2nX) to the cross sections σ^exp(γ, xn) were separated using the multiplicity transition functions F ₁ ^theor = σ^theor(γ, 1nX)/σ^theor(γ, xn) and F ₂ ^theor = σ^theor(γ, 2nX)/σ^theor(γ, xn), calculated within an updated version of the pre-equilibrium model of photonuclear reactions. New evaluated data for both partial reaction cross sections, i.e., σ^eval (γ, 1nX) = F ₁ ^theorσ^exp(γ, xn) and σ^eval(γ, 2nX) = F ₂ ^theorσ^exp(γ, xn), were obtained. The cross sections σeval(γ, nX) and σ^eval.(γ, 2nX) evaluated using the theoretically calculated functions F _1,2^theor are consistent with the Livermore data, but substantially contradict the Saclay data.     

Negative parity states in144Nd and multipolarity of gamma-transitions from 1− to 2+ states by beta-gamma-gamma angular correlation method

Some of the low-lying states in many isotopes¹⁴⁴Nd,¹⁴⁸Sm,¹⁵²Gd and¹⁵⁶Gd show a similar typical behaviour. The first 2⁺ is regarded as a single quadrupole phonon state and 3⁻ as a single octupole phonon state. The levels with the spins and parities 1⁻, 5⁻, 3⁻, 4⁻, etc. are considered due to the simultaneous excitation of quadrupole and octupole phonons. If this consideration is correct, then the transition fromJ ⁻ to 2⁺ states must contain an appreciableE3 content. Theβ-γ-γ angular correlation coefficients for the cascade ofβ-rays ofE _max 800 keV→γ-rays of 1489 keV→γ-rays of 696 keV are used to estimateE3 content inE1 transition in¹⁴⁴Nd.     

Free-field representations and geometry of some Gepner models

The geometry of the k ^K Gepner model, where k + 2 = 2K, is investigated by a free-field representation known as the “bcβγ” system. Using this representation, we directly show that the internal sector of the model is given by Landau-Ginzburg ℂ ^K /ℤ_2K orbifold. Then we consider the deformation of the orbifold by a marginal antichiral-chiral operator. Analyzing the chiral de Rham complex structure in the holomorphic sector, we show that it coincides with chiral de Rham complex of some toric manifold, where toric data are given by certain fermionic screening currents. This allows relating the Gepner model deformed by the marginal operator to a σ-model on the CY manifold realized as a double cover of ℙ ^{K − 1} with ramification along a certain submanifold.     

The phase diagram of (NH4I)x(KI)1−x

The χ,T phase diagram of (NH₄I)_x(KI)_1−x has been determined using neutron diffraction experiments and dielectric spectroscopy. At low temperatures and with decreasing χ, the sequence γ, β, ε and glass phase has been detected. The critical concentration χ_c≈0.55 separates the glassy phase with frozen-in orientational disorder from the ε phase which reveals long-range orientational order. Close to χ_c our experiments reveal evidence for two subsequent glass transitions.     

Experimental investigation of the angular dependence of photon-induced differential cross-sections of L X-rays from U,Th and Bi at 59.5 keV

Summary The differential cross-sections for the emission of L_ρ, L_α, L_β and L_γ groups of L X-ray lines from U, Th and Bi have been measured at different angles varying from 45° to 135° at intervals of 15°. The vacancies were created by 59.5 keV γ-rays from²⁴¹Am source and L X-rays were measured using a Si(Li) detector. It is found that the L_γ and L_β groups of L X-rays are isotropic, the L_ρ and L_α groups are anisotropic in the spatial distribution. The authors of this paper have agreed to not receive the proofs for correction.     

Beta-gamma-gamma directional correlation in103Rh

β-γ-γ directional correlation studies for the cascades (i)β-rays ofE _max=0.12 MeV,γ-rays of 557 keV andγ-rays of 53 keV and (ii)β-rays ofE _max=0.21 MeV,γ-rays of 444 keV andγ-rays of 53 keV have been made. The triple correlation functionsW(θ) were obtained to beW(θ)=1+(−0.153±0.031)P ₂(cosθ)+(0.004±0.035)P ₄(cosθ) forβ-rays ofE _max 0.12 MeV→557→53 keV cascade andW(θ)=1+(0.163±0.042)P ₂(cosθ)+(−0.035±0.058)P ₄(cosθ) forβ rays ofE _max=0.21 MeV→444 keV→53 keV cascade. Spins and parities of the 650, 537 and 93 keV levels of¹⁰³Rh are deduced by triple angular correlation and the internal conversion coefficient studies. Multipolarities of the transitions are also determined.     

A Kind of Four-Mode Nonlinear Entangled State Representation in Quantum Optics

Based on the technique of integration within an ordered product of nonlinear bosonic operators, we construct a new four-mode nonlinear entangled state | α,β,γ〉 _λ,μ in 4-mode Fock space, which can make up a complete set. Its properties and applications are discussed. A possible scheme to generate this state is also presented.