Dependence of Fluorescence Properties of Compounds from Psoralen,Angelicin, and Carbazole Series on the Character of Their Terminal Substituents

Absorption, luminescence excitation and emission spectra of nine compounds from 4,8,4'-trimethylpsoralen, 4,4'-dimethylangelicin, and 1,2,3,4-tetrahydrocarbazole series with various terminal substituents were studied in water and 2-propanol. Proceeding from the data obtained in the present and also some previous studies we have formulated the main rules concerning a general mechanism of changes in the fluorescence characteristics of DNA-specific dyes depending on their chemical structure, substrate properties, and measurement medium.     

Hadrons with charmed quarks in matter

We investigate the decay width of excited charmonium states at finite nuclear density with simultaneous modification of both D- and -mesons in nuclear matter. The strongest effect is found for the -meson. The medium modification can be detected by dilepton spectroscopy as substantial broadening and anomalous absorption.Received: 30 September 2002, Published online: 22 October 2003PACS: 13.25.Gv Decays of , , and other quarkonia - 14.40.Lb Charmed mesons - 14.65.Dw Charmed quarks - 24.85. + p Quarks, gluons, and QCD in nuclei and nuclear processes     

Phenomenology of the Λ/Σproduction ratio in pp collisions

We show that the recently measured asymmetry in helicity-angle spectra of the Λ-hyperons, produced in the reaction pp → K ⁺Λp reaction, and the energy dependence of the total pp → K ⁺Λp cross-section can be explained consistently by the same Λp final-state interaction. Assuming that there is no final-state interaction in the Σ⁰ p channel, as suggested by the available data for the reaction pp → K ⁺Σ⁰ p, we can also reproduce the energy dependence of the Λ/Σ⁰ production ratio and, in particular, the rather large ratio observed near the reaction thresholds. The nominal ratio of the Λ and Σ⁰ production amplitudes squared, i.e. when disregarding the final-state interaction, turns out to be about 3, which is in line with hyperon production data from proton and nuclear targets available at high energies.     

The K<Superscript>-</Superscript>α scattering length and the reaction dd↦αK<Superscript>+</Superscript>K<Superscript>-</Superscript>

We present predictions for the K^-α scattering length obtained within the framework of the multiple-scattering approach. Evaluating the pole position of the K^-α scattering amplitude within the zero-range approximation, we find a loosely bound K^-α state with a binding energy of E_R = - 2,..., - 7 MeV and a width Γ_R = 11,..., 18 MeV. We propose to measure the K^-α scattering length through the final-state interaction between the α and K^--meson produced in the reaction dd↦αK⁺K^-. It is found that the K^-α invariant-mass distribution from this reaction at energies near the threshold provides a new tool to determine the s-wave K^-α scattering length.     

Nuclear-spin-lattice relaxation in the organic superconductor (BEDT-TTF)2Cu[N(CN)2]Br0.8Cl0.2

The behavior of the spin-lattice relaxation rate of ¹H nuclei in the organic superconductor (BEDT-TTF)₂Cu[N(CN)₂]Br_0.8Cl_0.2 in the temperature interval 12–319 K is investigated. A relaxation rate maximum, which depends on the resonance frequency and is associated with thermally activated vibrations of the end ethylene groups in the BEDT-TTF molecules, is observed in the vicinity of 270 K. The relaxation rate is observed to deviate from Korringa behavior at T<100 K. These deviations can be attributed to the existence of strong antiferromagnetic spin correlations. Fiz. Tverd. Tela (St. Petersburg) 39, 39–41 (January 1997)     

Backward pion-nucleon scattering

A global analysis of the world data on differential cross-sections and polarization asymmetries of backward pion-nucleon scattering for invariant collision energies above 3GeV is performed in a Regge model. Including the N_a\ensuremath N_{\alpha} , N_g\ensuremath N_{\gamma} , D_d\ensuremath \Delta_{\delta} and D_b\ensuremath \Delta_{\beta} trajectories, we reproduce both angular distributions and polarization data for small values of the Mandelstam variable u , in contrast to previous analyses. The model amplitude is used to obtain evidence for baryon resonances with mass below 3GeV. Our analysis suggests a G₃₉\ensuremath G_{39} -resonance with a mass of 2.83GeV as member of the D_b\ensuremath \Delta_{\beta} -trajectory from the corresponding Chew-Frautschi plot.     

Investigation of high energy lightest nuclei produced in the interaction of protons with incident momenta from 2 to 10 GeV/c with Be,Al, Cu,Ta

The yields of protons and light fragments at 3·5° were measured for proton nuclei reactions. Experimental data for deuteron production are discussed in terms of coalescence models.Presented at the symposium Mesons and Light Nuclei, Bechyn, Czechoslovakia, May 27–June 1, 1985.