Comparison among Hamiltonian light-front formalisms at q+ = 0 and q+ <> 0: space-like elastic form factors of pseudoscalar and vector mesons

The electromagnetic elastic form factors of pseudoscalar and vector mesons are analyzed for space-like momentum transfers in terms of relativistic quark models based on the Hamiltonian light-front formalism elaborated in different reference frames (q+ 0 and q+ 0). As far as the one-body approximation for the electromagnetic current operator is concerned, it is shown that the predictions of the light-front approach at q+=0 should be preferred, particularly in case of light hadrons, because of: i) the relevant role played by the Z-graph at q+ 0, and ii) the appropriate elimination of spurious effects, related to the orientation of the null hyperplane where the light-front wave function is defined.Comment: version to appear in Phys. Rev. C. No change in the results and in the conclusion

Manifestation of three-body forces in three-body Bethe-Salpeter and light-front equations

Bethe-Salpeter and light-front bound state equations for three scalar particles interacting by scalar exchange-bosons are solved in ladder truncation. In contrast to two-body systems, the three-body binding energies obtained in these two approaches differ significantly from each other: the ladder kernel in light-front dynamics underbinds by approximately a factor of two compared to the ladder Bethe-Salpeter equation. By taking into account three-body forces in the light-front approach, generated by two exchange-bosons in flight, we find that most of this difference disappears; for small exchange masses, the obtained binding energies coincide with each other.Comment: 24 pages, 8 figures, submitted in Few-Body System

THE APPLICATION OF SCANNING ELECTRON MICROSCOPY USING ENERGY- AND WAVELENGTH DISPERSIVE SPECTROMETERS FOR CHEMICAL DATING OF URANIUM MINERALIZATION ON THE EXAMPLE OF CARBONACEOUS SHALES OF THE DABANZHALGA SUITE (EAST SAYAN)

On the one hand, the widespread use of electron microprobe analysis in the version of a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS) and, on the other hand, the comparability of the metrological characteristics of the EDS and wavelength dispersive spectrometry (WDS) in the case of determining the major components of minerals are a favourable background for investigating the possibility of using SEM-EDS for chemical dating of uranium mineralization. Carbonaceous-siliceous formations of the Dabanzhalga suite are widespread in carbonate deposits of the Lower Paleozoic in the Oka structural-formational zone of the East Sayan and represent deep-water deposits of the back-arc basin. All varieties of carbonaceous-siliceous rocks of the Dabanzhalga suite are characterized by increased U, Au, Ag, Pt, Pd, Mo, V, P, Cu. Their amounts are 5–10 times higher than those for other black shale deposits of the Eastern Sayan. Uranium forms its minerals – uraninite and brannerite, in association with carbonaceous matter and sulfides, and is also part of anhydrous phosphates – xenotime, monazite. The paper presents data on the composition and dating of brannerite and uraninite in samples of carbonaceous-siliceous shale sampled at three sites: Uber-Zhadoy, Deed-Khara-Zhalga and Erye-Khara-Zhalga. The obtained estimates of the isochronous dates of uraninite and brannerite grains for these areas are 523±26, 506±10, and 511±17 Ma, respectively. It was shown that these dates could be compared with the age of metamorphism at the Sukhoi Log deposit, estimated using modern methods of isotope geochronology. It should be noted that the average estimates of the dates of uraninite and brannerite in all studied areas of the Dabanzhalga suite are lower than the corresponding estimates of the isochronous date, which is probably due to the partial loss of radiogenic lead. For the Uber-Zhadoy site, a comparison of the EDS and WDS data was carried out, and it was shown that when using the EDS data, there is an underestimation of the Pb content in uraninite, and, as a consequence, an underestimation of the age of uraninite

Nataliakulikite, Ca4Ti2(Fe3+,fe2+)(Si,fe3+,al)o11, a new perovskite-supergroup mineral from hatrurim basin, negev desert, Israel

Nataliakulikite, Ca4Ti2(Fe3+,Fe2+)(Si,Fe3+,Al)O11, is a mineral intermediate between perovskite CaTiO3 and brownmillerite Ca2(Fe,Al)2O5. It was discovered as a minor mineral in a high-temperature pyrometamorphic larnite-gehlenite rock at the Nahal Morag Canyon of the Hatrurim Basin, Israel. Nataliakulikite is associated with larnite, flamite, gehlenite, magnesioferrite, Fe3+-rich perovskite, fluorapatite, barite, Hashemite, and retrograde phases (afwillite, hillebrandite, portlandite, calcite, ettringite, hydrogarnet, and other hydrated Ca-silicates). The mineral forms brown subhedral or prismatic grains (up to 20 µm) and their intergrowths (up to 50 µm). Its empirical formula (n = 47) is (Ca3.992Sr0.014U0.004)(Ti1.933Zr0.030Nb0.002) (Fe3+0.610Fe2+0.405Cr0.005Mn0.005)(Si0.447Fe3+0.337Al0.216)O11 and shows Si predominance in tetrahedral site. The unit-cell parameters (HRTEM data) and space group are: a = 5.254, b = 30.302, c = 5.488 Å, V = 873.7 Å3, Pnma, Z = 4. These dimensions and Electron backscatter diffraction (EBSD) data strongly support the structural identity between nataliakulikite and synthetic Ca4Ti2Fe3+2O11 (2CaTiO3·Ca2Fe3+2O5), an intermediate compound in the system CaTiO3-Ca2Fe3+2O5. In general, this mineral is a Si-Fe2+-rich natural analog of synthetic Ca4Ti2Fe3+2O11. The X-ray powder diffraction data (CuKα-radiation), calculated from unit-cell dimensions, show the strongest lines {d [Å], (Icalc)} at: 2.681(100), 1.898(30), 2.627(26), 2.744(23), 1.894(22), 15.151(19), 1.572(14), 3.795(8). The calculated density is 4.006 g/cm3. The crystal structure of nataliakulikite has not been refined because of small sizes of grains. The Raman spectrum shows strong bands at 128, 223, 274, 562, and 790 cm−1. Nataliakulikite from the Hatrurim Basin crystallized under the conditions of combustion metamorphism at high temperatures (1160–1200◦C) and low pressures (HT-region of the spurrite-merwinite facies). © 2019 by the authors. Licensee MDPI, Basel, Switzerland.Russian Science Foundation, RSF: 0330-2016-0004, 17-17-01056, IGM SD 0330-2016-0005Ben-Gurion University of the Negev, BGUThis research was funded by the Russian Science Foundation, grant number 17-17-01056. The field work and sample collection was partly supported the State assignment projects (IGM SD 0330-2016-0005, 0330-2016-0004). Acknowledgments: The authors would like to thank M.V. Khlestov (IGM SD RAS) for technical assistance at SEM studies. Yevgeny Vapnik (Ben-Gurion University, Beer-Sheva, Israel) is thanked for providing of fruitful field trips in the Hatrurim Basin in 2004 and 2019. The last version of the manuscript was improved through comments and suggestions by T. Perepelova (IGM, Novosibirsk). We are highly appreciative of the valuable comments and suggestions of two anonymous reviewers

Formation of 24Mg* in the Splitting of 28Si Nuclei by 1-GeV Protons

The 28Si(p, p' gamma)24Mg reaction has been studied at the ITEP accelerator by the hadron-gamma coincidence method for a proton energy of 1 GeV. Two reaction products are detected: a 1368.6-keV gamma-ray photon accompanying the transition of the 24Mg* nucleus from the first excited state to the ground state and a proton p' whose momentum is measured in a magnetic spectrometer. The measured distribution in the energy lost by the proton in interaction is attributed to five processes: the direct knockout of a nuclear alpha cluster, the knockout of four nucleons with a total charge number of 2, the formation of the DeltaSi isobaric nucleus, the formation of the Delta isobar in the interaction of the incident proton with a nuclear nucleon, and the production of a pi meson, which is at rest in the nuclear reference frame. The last process likely corresponds to the reaction of the formation of a deeply bound pion state in the 28P nucleus. Such states were previously observed only on heavy nuclei. The cross sections for the listed processes have been estimated.Comment: 14 pages, 3 figures submitted to JETP Letter

Uakitite, VN, a new mononitride mineral from uakit iron meteorite (IIAB)

Uakitite was observed in small troilite–daubréelite (±schreibersite) inclusions (up to 100 µm) and in large troilite–daubréelite nodules (up to 1 cm) in Fe-Ni-metal (kamacite) of the Uakit iron meteorite (IIAB), Republic of Buryatia, Russia. Such associations in the Uakit meteorite seemed to form due to high-temperature (&gt;1000 °C) separation of Fe-Cr-rich sulfide liquid from Fe-metal melt. Most inclusions represent alternation of layers of troilite and daubréelite, which may be a result of solid decay of an initial Fe-Cr-sulfide. These inclusions are partially resorbed and mainly located in fissures of the meteorite, which is now filled with magnetite, and rarely other secondary minerals. Phase relations indicate that uakitite is one of the early minerals in these associations. It forms isometric (cubic) crystals (in daubréelite) or rounded grains (in schreibersite). The size of uakitite grains is usually less than 5 µm. It is associated with sulfides (daubréelite, troilite, grokhovskyite), schreibersite and magnetite. Carlsbergite CrN, a more abundant nitride in the Uakit meteorite, was not found in any assemblages with uakitite. Physical and optical properties of uakitite are quite similar to synthetic VN: yellow and transparent phase with metallic luster; Mohs hardness: 9–10; light gray color with a pinky tint in reflected light; density (calc.) = 6.128 g/cm3. Uakitite is structurally related to the osbornite group minerals: carlsbergite CrN and osbornite TiN. Structural data were obtained for three uakitite crystals using the electron backscatter diffraction (EBSD) technique. Fitting of the EBSD patterns for a synthetic VN model (cubic, Fm-3m, a = 4.1328(3) Å; V = 70.588(9) Å3; Z = 4) resulted in the parameter MAD = 0.14–0.37° (best-good fit). Analytical data for uakitite (n = 54, in wt. %) are: V, 71.33; Cr, 5.58; Fe, 1.56; N, 21.41; Ti, below detection limit (&lt;0.005). The empirical formula (V0.91Cr0.07Fe0.02)1.00N1.00 indicates that chromium incorporates in the structure according to the scheme V3+ → Cr3+ (up to 7 mol. % of the carlsbergite end-member). © 2020 by the authors. Licensee MDPI, Basel, Switzerland.Russian Foundation for Basic Research, RFBR: 17-05-00129, IGM SD 0330-2016-0005Government Council on Grants, Russian FederationMinistry of Science and Higher Education of the Russian FederationFunding: The investigations were partly supported by RFBR (grant 17-05-00129) and the State assignment project (IGM SD 0330-2016-0005). This work was also supported by the Initiative Project of Ministry of Science and Higher Education of the Russian Federation and by Act 211 of the Government of the Russian Federation, agreement no. 02.A03.21.0006

Form factors of the exotic baryons with isospin I=5/2

The electromagnetic form factors of the exotic baryons are calculated in the framework of the relativistic quark model at small and intermediate momentum transfer. The charge radii of the E+++ baryons are determined.Comment: 12pages, 2 figure

Deuteron-Proton Elastic Scattering at Intermediate Energies

The deuteron-proton elastic scattering has been studied in the multiple scattering expansion formalism. The essential attention has been given to such relativistic problem as a deuteron wave function in a moving frame and transformation of spin states due to Wigner rotation. Parameterization of the nucleon-nucleon $t$-matrix has been used to take the off-energy shell effects into account. The vector, $A_y,$ and tensor, $A_{yy}$, analyzing powers of the deuteron have been calculated at two deuteron kinetic energies: 395 MeV and 1200 MeV. The obtained results are compared with the experimental data