Production and decay of the π−π−π+ system in the reaction π−d → dπ−π−π+ at 9 GeV/c

In this paper we present a study of the reaction π^?d → π^?π^?π⁺d at 9 GeV/c. The mass spectra are in fair agreement with the predictions of a reggeized pion-exchange Deck model. However, the s-channel azimuthal angular distribution indicates a ?-exchange Deck contribution. The results of the partial-wave analysis of the (3π)^? system are compared with those obtained in a hydrogen target: the J^P = 2⁺ contribution is very small (at most 1.5 ± 1.2)% in our data, which are dominated by J^P = 1⁺ for low mass, whereas the J^P = 0^?, 1⁺, 2^? have comparable importance in the higher mass region.     

Zeros of the π+π− → π+π− amplitude

Recent data on the reaction $\text{p}\text{p}\text{→ π}{}^{\mathrm{?}}\text{π}{}^{\mathrm{+}}$ show four conspicuous dips in the angular distribution at fixed values of ν = t?u. The conjecture is made that the channel π^?π⁺ → π^?π⁺ has zeros at the same ν values. Using data of the CERN-Munich group, one can follow the zeros through the whole Mandelstam plane. The zeros pass through the intersections of s and t channel poles, as the Veneziano model predicts; however, away from these intersections, they propagate in a fashion systematically quite different from Veneziano's ansatz.     

Depolarization currents in the Na0.5Bi8.5Ti2Nb4O27 and Na0.5Bi8.5Ti2Ta4O27 layered ferroelectrics

The influence of the prehistory on the electrical properties of layered ferroelectrics is investigated. It is established that the heating of short-circuited samples of the nonpolarized ceramic material Na_0.5Bi_8.5Ti₂Nb₄O₂₇ leads to the appearance of maxima of the current at temperatures below the Curie point only in the case of preliminary ageing of the samples. Original Russian Text ? A.I. Burkhanov, Yu.V. Kochergin, K. Bormanis, A. Kalvane, M. Dambekalne, 2009, published in Fizika Tverdogo Tela, 2009, Vol. 51, No. 7, pp. 1393–1394.     

Structural study of the Lu2Si2O7-Sc2Si2O7 system

Different compositions in the Lu₂Si₂O₇-Sc₂Si₂O₇ system have been synthesized following the ceramic method. All XRD patterns are compatible with the thortveitite structure (β-RE₂Si₂O₇ polymorph). Unit cell parameters change linearly with composition, which indicates a complete solid solubility of Sc₂Si₂O₇ in Lu₂Si₂O₇. ²⁹Si MAS NMR spectra show a decrease of the ²⁹Si chemical shift with increasing Sc content. A correlation reported in the literature to predict ²⁹Si chemical shifts in silicates is applied here to obtain the theoretical variation in ²⁹Si chemical shift values in the system Lu₂Si₂O₇-Sc₂Si₂O₇ and the results compare favourably with the values obtained experimentally. The FWHM values of the ²⁹Si MAS NMR curves indicate a random distribution of Lu and Sc in the structure of the intermediate members. Finally, the IR study of the system confirms the solubility of Sc₂Si₂O₇ in Lu₂Si₂O₇, showing the splitting of several modes in the intermediate members and a linear shift of the frequency on going from one end-member to the other.     

Fluoride glasses in the InF3-GaF3-YF3-PbF2-CaF2-ZnF2 system

New glasses have been synthesized in a multicomponent system based on indium fluoride. Samples of a few mm in thickness were obtained. They are transparent and homogeneous. Main physical properties such as density, characteristic temperatures, density, thermal expansion and refractive index have been measured. The evolution versus composition is reported for samples with the formula: (35−x) InF₃-xGaF₃-10YF₃-25PbF₂-15CaF₂-15ZnF₂. T_g lies between 260 and 296 °C while melting starts around 480 °C. Glass samples are stable at room temperature. By comparison with other standard fluoride glasses, they exhibit higher refractive index and density.     

Glass formation in the As2Se3-As2Te3-Sb2Te3 system

Chalcogenide glasses from the As₂Se₃-As₂Te₃-Sb₂Te₃ system were synthesized for the first time. The glass-forming region was determined by X-ray diffraction and electron microscopic analyses.The basic physicochemical parameters such as density (d), microhardness (HV) and temperatures of phase transformations (glass transition T_g, crystallization T_cr and melting T_m) were measured. Compactness and some thermomechanical characteristics such as volume (V_h) and formation energy (E_h) of micro-voids in the glassy network as well as the elasticity module (E) were calculated. The glass-forming ability was evaluated according to Hruby's criteria (K_G). The correlation between composition and properties of the (As₂Se₃)_x(As₂Te₃)_y(Sb₂Te₃)_z glasses was established and comprehensively discussed.     

Electrical transport and superconductivity in the Al2O3-Bi2Sr1.8Ca1.2Cu2Oy and MgO-Bi2Sr1.8Ca1.2Cu2Oy composites

We have measured the resistivities of Al₂O₃-Bi₂Sr_1.8Ca_1.2Cu₂O_y and MgO-Bi₂Sr_1.8Ca_1.2Cu₂O_y composites with the nominal Bi₂Sr_1.8Ca_1.2Cu₂O_y volume fraction, ₂₂₁₂, ranging from 0.15 to 1.00. For the Al₂O₃-Bi₂Sr_1.8Ca_1.2Cu ₂O_y composites, we find for the samples with ₂₂₁₂≥0.6 that the superconducting transition temperature, T_c, is not disturbed by the addition of Al₂O₃. For ₂₂₁₂<0.3, no zero-resistivity state is observed. For the MgO-Bi₂Sr_1.8Ca_1.2Cu₂O_y composites, T_c is barely disturbed for the samples with ρ₂₂₁₂≥0.7. No superconducting state is observed for the samples with ρ₂₂₁₂<0.35. The variation of (300 K) with ρ₂₂₁₂ indicates a three-dimensional percolating Bi-Sr-Ca-Cu-O matrix occurring at ρ₂₂₁₂≈0.19 and ≈0.15 in Al₂O₃-Bi₂Sr_1.8Ca_1.2 Cu₂O_y and MgO-Bi₂Sr_1.8Ca_1.2Cu₂O_y, respectively. Both resistivity and magnetization measurements suggest that the reactions of Bi₂Sr_1.8Ca_1.2Cu₂O_y with MgO are weaker than with Al₂O₃.     

X-ray study of phase transitions in the system of solid solutions K2Pb4Nb10O30-Na2Pb4Nb10O30-K6W4Nb6O30

Boundaries of morphotropic phase transitions region in the system of solid solutions K₂Pb₄Nb₁₀O₃₀-Na₂Pb₄Nb₁₀O₃₀-K₆W₄Nb₆O₃₀ with the structure of the tetragonal tungsten bronze have been specified. Presence of the second morphotropic phase transition, perpendicular to the first one has been revealed. The temperature dependences of the structural parameters of some compounds have been investigated. The compounds with high values of Curie temperatures and working temperatures have been obtained.     

Model-independent analysis of the reaction π+p → π+π−Δ++

The high-statistics data on π⁺p → π⁺π^?Δ⁺⁺ at 7.1 GeV/c are used in a detailed analysis using model-independent means. Positivity conditions are found to be violated, although there is overlap between the positivity domain and the error ellipsoid. Using points modified to satisfy positivity, we confirm certain aspects of a previous model-dependent analysis. In particular, the percentage S-wave is found to be close to the lower limit consistent with the ππ moments alone. A number of quark-model predictions are confronted with the data and also with our modified points, and reasonable but not total agreement is observed.     

Magnetic structure of the Sm5Ge4-type Tb2Ti3Ge4

The orthorhombic Sm₅Ge₄-type Tb₂Ti₃Ge₄ shows square modulated non-collinear magnetic ordering with wave vector K=[±1/3, 1/2, 1/2] at 2 K. The terbium magnetic moments lie in the bc plane and magnetic moment value of 7.5(2) μ_B/Tb is obtained at 2 K.     

Phase separation with charge self-organization in the Tb0.95Bi0.05MnO3, Gd0.75Ce0.25Mn2O5, and Eu0.8Ce0.2Mn2O5 manganite multiferroics

New doped manganite multiferroics Tb_0.95Bi_0.05MnO₃, Gd_0.75Ce_0.25Mn₂O₅, and Eu_0.8Ce_0.2Mn₂O₅, which are semiconductors, have been grown and studied. The starting dielectric multiferroics TbMnO₃ and RMn₂O₅ (R = Gd and Eu) have close magnetic and ferroelectric ordering temperatures of 30–40 K. The crystals studied are multiferroics in which states with giant permittivity and ferromagnetism coexist at room temperature. An analysis of the dielectric properties suggests that, at temperatures T ≥ 180 K, these crystals undergo a phase separation involving dynamic periodic alternation of quasi-2D layers of mixed-valence manganese ions, a process accounting for the onset of charge-induced ferroelectricity. At low temperatures (T < 100 K), a small phase volume in the crystals is occupied by as-grown quasi-2D layers containing dopants and carriers. Most of the crystal volume is occupied by the carrier-free dielectric phase. Thermally activated hopping conduction involving carrier self-organization in the crystal matrix with ferroelectric frustrations drives a phase transition to the state of charge-induced ferroelectricity at T ∼ 180 K. Original Russian Text ? V.A. Sanina, E.I. Golovenchits, V.G. Zalesskiĭ, 2008, published in Fizika Tverdogo Tela, 2008, Vol. 50, No. 5, pp. 874–882.     

An investigation of the processes e+e−→μ+μ−γ and e+e−→e+e−γ

The reactions e⁺e^?→μ⁺μ^?γ and e⁺e^?→e⁺e^?γ have been studied with the CELLO detector at the PETRA storage ring. Data have been collected from $\text{s}\text{=14}\text{GeV up to}\text{46.8}\text{GeV}$. In a Dalitz plot analysis of the data, good agreement is found with QED, except for the region Mx_μγe>0.8 where the probability that QED describes the high energy data is at the percent level.     

Electrical and electrochemical properties of glass-ceramic electrolytes in the systems Li2S-P2S5-P2S3 and Li2S-P2S5-P2O5

Electrical and electrochemical properties of the 70Li₂S·(30 − x)P₂S₅·xP₂S₃ and the 70Li₂S·(30 − x)P₂S₅·xP₂O₅ (mol%) glass-ceramics prepared by the mechanical milling technique were investigated. Glass-ceramics with 1 mol% P₂S₃ and 3 mol% P₂O₅ showed the highest conductivity of 5.4 × 10^− 3 S cm^− 1 and 4.6 × 10^− 3 S cm^− 1, respectively. Moreover, these glass-ceramics showed higher electrochemical stability than the 70Li₂S·30P₂S₅ (mol%) glass-ceramic. From the XRD patterns of the obtained glass-ceramics, trivalent phosphorus and oxygen were incorporated into the Li₇P₃S₁₁ crystal. We therefore presume that the Li₇P₃S₁₁ analogous crystals, which were formed by incorporating trivalent phosphorus and oxygen into the Li₇P₃S₁₁ crystal, improve the electrical and electrochemical properties of the glass-ceramics. An all-solid-state cell using the 70Li₂S·29P₂S₅·1P₂S₃ (mol%) glass-ceramic as solid electrolyte operated under the high current density of 12.7 mA cm^− 2 at the high temperature of 100 °C. The cell showed an excellent cyclability of over 700 cycles without capacity loss.     

A study of the dalitz plot in the decay KL0 → π+π−π0

The results are presented of an analysis of 4709 fully reconstructed K_L⁰ → π⁺π^?π⁰, observed in a hydrogen bubble chamber. The data fit to a linear π⁰ energy spectrum to give a slope parameter g = 0.610 ± 0.022.     

Analysis of FTIR spectra of CH2BrCl; the ν4 and ν5 fundamentals and their hot-bands ν4+ν6−ν6 and ν5+ν6−ν6

The infrared spectrum of isotopically pure CH₂⁷⁹BrCl has been recorded at a resolution of 0.0023 cm⁻¹ (FWHM) in the range 550-800 cm⁻¹ with a Bruker IFS 120 HR Fourier transform spectrometer in Wuppertal. Here we report the full rotational analysis of the ν₄ and ν₅ fundamentals and of the hot-bands ν₄+ν₆−ν₆ and ν₅+ν₆−ν₆. Ground state combination differences were constructed for all bands, yielding improved ground state constants, up to quartic terms, as well as reliable rotational constants for the ν₄, ν₅, and ν₆ states.     

High-resolution infrared spectrum of the ν3 and ν2 + ν3 − ν2 bands of 14N16O2

The infrared absorption spectrum of the ν₃ band of ¹⁴NO₂ has been recorded with a resolution and a frequency accuracy much improved over the previous investigations. The K- and N-line assignments have been greatly extended and a more accurate set of spectroscopic constants derived. Several lines in the subbands with K_a ≥ 3 have been observed to be doubled by spin-rotation interaction and spin-rotation interaction constants have been obtained. Several weak series of lines in the spectrum (K_a = 0, 1, 2, and 3) have been unambiguously assigned to the “hot band” ν₂ + ν₃ ? ν₂. Lines of the K_a = 3, 4, 5, and 6 sub-bands of ν₃ have been found to be perturbed by a Coriolis interaction with the K_a = 4, 5, 6, and 7 levels of 2ν₂.     

Cross section determination for the reaction K+p → K+pπ+π−π0 and K+π+π+π−n at 8.2 and 16 GeV/c

The cross sections for the reactions: (a) K⁺p → K⁺pπ⁺π^?π⁺ and (b) K⁺p → K⁺π⁺π⁺π^?n have been determined at 8.2 and 16 GeV/c with the following results:at 8.2 GeV/c: (a) 0.99 ± 0.07 mb, (b) 0.41 ± 0.04 mb;at 16 GeV/c: (a) 0.72 ± 0.05 mb, (b) 0.28 ± 0.05 mb.Using the available data at other energies, the cross-section dependence of these reactions on the incident momentum is discussed.     

Study of the photon spectrum in the decay KS0→π+π−γ

The branching ratio $\text{Λ(}\text{K}{}_{\mathrm{<mtext>S</mtext>}}{}^0\text{→π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{γ)}\text{Λ(}\text{K}{}_{\mathrm{<mtext>S</mtext>}}{}^0\text{→π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{)}$ has been determined to be (2.68±0.15)×10^?3 for photon energies $\text{E}{}_{\mathrm{\gamma }}{}^1$ greater than 50 MeV in the K_S⁰ rest frame. The decay K_S⁰→π⁺π^?γ is found to be dominated by the internal bremsstrahlung transition. The branching rato of a possible direct transition is found to be less than 0.06 × 10^?3 at 90% confidence level for $\text{E}{}_{\mathrm{\gamma }}{}^1\text{> 50}\text{MeV}$.     

Experimental study of the final state interactions in the decays of 4ΛH → π−p3H amd 4ΛHe → π−p3He

Experimental results concerning the decay modes _Λ⁴H → π^?p³H and _Λ⁴He → π^?p³He are presented. A sample of _Λ⁴He → π^?p³He decays almost free from a contamination of other hypernuclear decay modes was selected. Some experimental distributions are compared with theoretical predictions.     

Bounds on the π0π0 amplitude

A new approach to the problem of constraining the scattering amplitudes by using axiomatically proved properties of unitarity, analyticity and crossing is developed. It is applied to obtain absolute and semi-phenomenological bounds on the π⁰π⁰ amplitude at points lying on the Mandelstam triangle, in particular at the physical threshold (scattering length) and at the symmetric point (which is used to define the coupling constant). We have already reported a less general and powerful approach which improved the previous results in this field. The present version, which constitutes a noticeable generalization of the method, allows a new improvement of the bounds, both absolute and semi-phenomenological.