γN→Δ\gamma N \to \Delta transition form factors in Quenched and NF=2N_F=2 QCD

Calculations of the magnetic dipole, electric quadrupole and Coulomb quadrupole amplitudes for the transition $\gamma N\to \Delta$ are presented both in quenched QCD and with two flavours of degenerate dynamical quarks.Comment: Lattice2003(Matrix), 3 page

Calculation of the N to Delta electromagnetic transition matrix element

We present results on the ratio of electric quadrupole to magnetic dipole amplitudes, $R_{EM}={\cal G}_{E2}/{\cal G}_{M1}$, for the transition $\gamma N to \Delta$ from lattice QCD. We consider both the quenched and the 2-flavor theory.Comment: 3 pages, 4 figures, talk presented at Lattice2002(matrixel); Layout of figures adjuste

Existence theorems in the geometrically non-linear 6-parametric theory of elastic plates

In this paper we show the existence of global minimizers for the geometrically exact, non-linear equations of elastic plates, in the framework of the general 6-parametric shell theory. A characteristic feature of this model for shells is the appearance of two independent kinematic fields: the translation vector field and the rotation tensor field (representing in total 6 independent scalar kinematic variables). For isotropic plates, we prove the existence theorem by applying the direct methods of the calculus of variations. Then, we generalize our existence result to the case of anisotropic plates. We also present a detailed comparison with a previously established Cosserat plate model.Comment: 19 pages, 1 figur

The nucleon to Delta electromagnetic transition form factors in lattice QCD

The electromagnetic nucleon to Delta transition form factors are evaluated using two degenerate flavors of dynamical Wilson fermions and using dynamical sea staggered fermions with domain wall valence quarks. The two subdominant quadrupole form factors are evaluated for the first time in full QCD to sufficient accuracy to exclude a zero value, which is taken as a signal for deformation in the nucleon-Delta system. For the Coulomb quadrupole form factor the unquenched results show deviations from the quenched results at low q^2 bringing dynamical lattice results closer to experiment, thereby confirming the importance of pion cloud contributions on this quantity.Comment: 15 pages, 8 Figure

Observation of String Breaking in QCD

We numerically investigate the transition of the static quark-antiquark string into a static-light meson-antimeson system. Improving noise reduction techniques, we are able to resolve the signature of string breaking dynamics for n_f=2 lattice QCD at zero temperature. This result can be related to properties of quarkonium systems. We also study short-distance interactions between two static-light mesons.Comment: 27 pages, 22 figures, changed decimal place of errors in 3 entries of Table, corrected reference

Momentum dependence of the N to Delta transition form factors

We present a new method to determine the momentum dependence of the N to Delta transition form factors and demonstrate its effectiveness in the quenched theory at $\beta=6.0$ on a $32^3 \times 64$ lattice. We address a number of technical issues such as the optimal combination of matrix elements and the simultaneous overconstrained analysis of all lattice vector momenta contributing to a given momentum transfer squared, $Q^2$.Comment: Talk presented at Lattice 2004 (spectrum), Fermilab, 21-26 Jun. 2004. 3 pages, 3 figures. One typo in phenomenological Ansatz correcte

The N to Delta electromagnetic transition form factors from Lattice QCD

The magnetic dipole, the electric quadrupole and the Coulomb quadrupole amplitudes for the transition \gamma N\to \Delta are calculated in quenched lattice QCD at \beta=6.0 with Wilson fermions. Using a new method combining an optimal combination of interpolating fields for the $\Delta$ and an overconstrained analysis, we obtain statistically accurate results for the dipole form factor and for the ratios of the electric and Coulomb quadrupole amplitudes to the magnetic dipole amplitude, R_{EM} and R_{SM}, up to momentum transfer squared 1.5 GeV^2. We show for the first time using lattice QCD that both R_{EM} and R_{SM} are non-zero and negative, in qualitative agreement with experiment and indicating the presence of deformation in the N- Delta system.Comment: 4 pages, 3 figure

Исследование системы РЗЭ (OH)3−NH4Cl при нагревании

The temporal evolution of neon pinch plasmas, generated in a 2kJ plasma focus device, has been investigated by x-ray spectroscopic methods for two sets of device parameters. These two sets lead to characteristic differences of the K-shell emission. Stationary models are shown to fail to explain the experimental observations even qualitatively. Transient spectra analysis shows that the characteristic differences observed can be referred to different transient modes of plasma dynamics. The spectra analysis includes beside resonance lines also dielectronic satellites and recombination continua. The results concerning the development of the plasma parameters achieved by the spectra modeling are supported by independent measurements of the time resolved K-shell emission and by optical streak images of the pinch plasma dynamics, which confirms the reliability of the transient spectroscopic analysis presented

Ultraviolet Imaging Observations of the cD Galaxy in Abell 1795: Further Evidence for Massive Star Formation in a Cooling Flow

We present images from the Ultraviolet Imaging Telescope of the Abell 1795 cluster of galaxies. We compare the cD galaxy morphology and photometry of these data with those from existing archival and published data. The addition of a far--UV color helps us to construct and test star formation model scenarios for the sources of UV emission. Models of star formation with rates in the range \sim5-20M_{\sun}yr$^{-1}$ indicate that the best fitting models are those with continuous star formation or a recent ($\sim4$ Myr old) burst superimposed on an old population. The presence of dust in the galaxy, dramatically revealed by HST images complicates the interpretation of UV data. However, we find that the broad--band UV/optical colors of this cD galaxy can be reasonably matched by models using a Galactic form for the extinction law with $E_{B-V}=0.14$. We also briefly discuss other objects in the large UIT field of view.Comment: To appear in the Astrophysical Journal. 14 AAS preprint style pages plus 7 figure

Silicate Treatment to Inhibit Corrosion of Hot, Potable Water Systems, Phase I

Research has been conducted to determine the variables involved in the use of the sodium silicate treatment technique and in the design of a system which utilizes or controls these variables for the efficient control of corrosion of steel, galvanized steel, and copper piping exposed to hot, potable water. Test loops were designed and constructed at nine selected sites to investigate the influence that temperature flow velocity, water chemistry, and silicate formulation and dosage have on the effectiveness of sodium silicate as a corrosion inhibitor for steel, galvanized steel, and copper piping exposed to heat (140°F and 180°F) in aggressive, potable water of four different compositions. Recommendations are made to conduct further research to determine ( 1) silicate treatment variables involved in treating low alkalinity and low hardness water; {2) the practicality of employing silicate treatment of hard water; (3) the effectiveness of zinc salts as a supplement to silicate; and (4) the corrosion resistance of ASTM A-268 Grade 409 stainless steel.AIR FORCE WEAPONS LABORATORY - Air Force Systems Command - Kirtland Air Force Base, New MericoOpe