Estimation of Excited State Dipolemoments from Solvatochromic Shifts–Effect of pH

Multicomponent, highly efficient, catalytic synthesis of some polysubstituted imidazole under solvent-free condition is reported. Characterization of polysubstituted imidazole have been carried out by X-ray diffraction (XRD) and spectral techniques. Electronic spectral studies reveal that their solvatochromic behavior depends not only on the polarity of the medium but also on the hydrogen bonding properties of the solvents. Specific hydrogen bonding interaction in polar solvents modulated the order of the two close lying lowest singlet states. The solvent effect on both the absorption and emission spectral results have been analyzed by multiple parametric regression analysis. Solvatochromic effects on the emission spectral position indicate the charge transfer (CT) character of the emitting singlet states both in a polar and a non polar environment. The fluorescence decays for the imidazole fit satisfactorily to a single exponential kinetics. The prototropic studies of N,N-dimethyl-4-(1,4,5-triphenyl-1H-imidazol-2-yl)naphthalen-1-amine (DTINA) reveal that two monocations [imidazole nitrogen protanated (MC1) and dimethylamino nitrogen protanated (MC2)] and a dication [both imidazole nitrogen and dimethylamino nitrogen protanated (DC)] are formed by protonation in both ground and excited states. These observations are in consistent with quantum chemical calculations.     

Exotic and excited-state meson spectroscopy and radiative transitions from lattice QCD

We discuss recent progress in extracting the excited meson spectrum and radiative transition form factors from lattice QCD.We mention results in the charmonium sector,including the first lattice QCD calculation of radiative transition rates involving excited charmonium states,highlighting results for high spin and exotic states.We present recent results on a highly excited isovector meson spectrum from dynamical anisotropic lattices.Using carefully constructed operators we show how the continuum spin of extracted states can be reliably identified and confidently extract excited states,states with exotic quantum numbers and states of high spin.This spectrum includes the first spin-four state extracted from lattice QCD.We conclude with some comments on future prospects.     

Chaotic transport and damping from θ-ruffled separatrices

Variations in magnetic or electrostatic confinement fields give rise to trapping separatrices, and neoclassical transport theory analyzes effects from collision-induced separatrix crossings. Experiments on pure electron plasmas now quantitatively characterize a broad range of transport and wave damping effects due to "chaotic" separatrix crossings, which occur due to equilibrium plasma rotation across θ-ruffled separatrices, and due to wave-induced separatrix fluctuations.     

η and η' mesons from lattice QCD

The large mass of the ninth pseudoscalar meson, the η', is believed to arise from the combined effects of the axial anomaly and the gauge field topology present in QCD. We report a realistic, 2+1-flavor, lattice QCD calculation of the η and η' masses and mixing which confirms this picture. The physical eigenstates show small octet-singlet mixing with a mixing angle of θ=-14.1(2.8)°. Extrapolation to the physical light quark mass gives, with statistical errors only, mη=573(6) MeV and mη'=947(142) MeV, consistent with the experimental values of 548 and 958 MeV.     

Single and double πo-photoproduction from the deuteron

Photoproduction of neutral pions from the deuteron has been studied for incident photon energies from 200 MeV to 792 MeV with the TAPS detector at the Mainz MAMI accelerator. Total and differential cross sections covering the full angular range have been obtained for coherent and incoherent single π^o-photoproduction. Good agreement between model predictions and the data was found for the coherent process. The incoherent cross section in the energy region of the Δ(1232)-resonance is overestimated by existing models. A comparison to model predictions indicates that final state interaction effects are much more important than for the coherent reaction. However, the angular dependence of the data in the Δ-peak region follows the pattern expected from the dominant excitation of the M₁₊-multipole on the free nucleon. The energy and angular dependence of single π^o-photoproduction in the second resonance region is remarkably different from the reaction on the free proton, indicating a strong nuclear effect. Finally the total cross section for double π^o-photoproduction from the deuteron has been measured for the first time and was used to estimate the cross section for double π^o-photoproduction from the neutron. Received: 24 June 1999 / Revised version: 30 August 1999     

Self-Organization of Topology and Weight Dynamics on Networks from Merging and Regeneration

We propose a model of weighted networks in which the structural evolution is coupled with weight dynamics. Based on a simple merging and regeneration process, the model gives powel-law distributions of degree, strength and weight, as observed in many real networks. It should be emphasized that, in our model, the nontrivial degree-strength correlation can be reproduced and in agreement with empirical data. Moreover, the size-growing evolution model is also presented to meet the properties of real-world systems.     

Φπ production in\bar pp annihilation from S and P states and in J/ψ decaysannihilation from S and P states and in J/ψ decays

Recent experiments at LEAR have found surprisingly large branching ratios for reactions $\bar NN \to \phi \pi $ from S-wave initial states while noφπ production is observed from P states of the $\bar pp$ system. Also, noφπ is seen in radiative J/ψ decays even though the rate forωπ is substantial. We calculate theφπ production rates for these three cases viaKK* intermediate states and $K\bar K$ rescattering using the dispersion relation technique; we find that the largeφπ rate in $\bar pp$ annihilations from S states can be reproduced with a reasonable cut-off for the dispersion integral; for J/ψ decays the calculatedφπ rate is compatible with the observed upper limit. We would, however, expectφπ to be seen from $\bar pp$ P-states, in contrast to experimental findings. Yet the branching ratio for $\bar pp \to K*\bar K$ via isospinI = 1 of $\bar pp$ ,¹ P ₁ state is not known; and therefore no definite conclusion can be drawn. We also compare the Dalitz plots we obtain for directφ production and forφ production via rescattering. Clear differences between the two theoretical distributions are observed; yet very high precision data would be required to establish the origin — direct production or rescattering — of theφ mesons. This observation supports the use of the isobar model in data analyses.     

Radio waves and γ-ray emission from astrophysical sources

A mechanism of X- and γ-ray emission by relativistic electrons at interaction with astrophysical objects (maser clouds) is considered and the contribution of this mechanism to the formation of a continuous spectrum and its correlation with radio-wave radiation are investigated. The radiation yield upon deexcitation of a quantum system by an electron exceeds that of “conventional” (i.e., without a change in the quantum-system state) bremsstrahlung at small nuclear charges (Z < 10) and may be about 8% of the total γ-ray intensity. It is shown that in the direction in which the γ-ray intensity increases, one should observe radio waves corresponding to a particular maser source.     

Reconstruction of HRTF from individualized tensor decomposition and modes

Far-field head-related transfer functions(HRTFs) vary with source direction, frequency and individual. Correspondingly, the dimensionality of a full set of HRTFs is huge and measurement or calculation of individualized HRTFs with high directional resolution could be difficult. A method to construct HRTFs with high directional resolution from a small set of directional measurements or calculations is proposed in present paper. Based on tensor decomposition of HRTFs, far-field HRTFs are decomposed...     

α decay energies and half-lives from a macroscopic-microscopic model

α decay energies of 323 heavy nuclei with Z≥82 are evaluated with a macroscopic-microscopic model. In this model, the macroscopic part is treated by the continuous medium model and the microscopic part consists of shell and pairing corrections based on the Nilsson potential. α decay half-lives are calculated by Viola-Seaborg formula. The results of α decay energies and half-lives are compared with experimental values and satisfactory agreement is found. The recoiling effect of the daughter nucleus on α decay half-life is also discussed.     

Inelastic α-scattering from 90Zr and 96Zr

The ⁹⁰Zr and ⁹⁶Zr(α, α') reactions have been studied at 35.4 MeV with an energy resolution of 35–50 keV. Angular distributions were measured between 10 and 50 degrees for an E_x range of 1.5 to 6.0 MeV. Spin assignments have been made on the basis of the shapes of the differential cross sections and by comparison with collective DWBA calculations. For ⁹⁶Zr discrepancies in spin assignments have been removed for several levels. Within the framework of the vibrational model isoscalar transition rates have been derived.     

Exploring hidden-charm and hidden-strange hexaquark states from lattice QCD

Based on five different ensembles of newly generated (2+1)-flavor configurations with pion mass of approximately m_π■(140-310) MeV, we present a lattice analysis of hidden-charm and hidden-strange hexaquarks with the quark content ■. The correlation matrices of two types of operators with J^PC=0⁺⁺, 0^-+, 1⁺⁺ and 1^-- are simulated to extract the masses of the hexaquark candidates, which are subsequently extrapolated to the physical pi...     

Relativity from Light Front and Bethe–Salpeter Equations

We present some results of two independent relativistic approaches to the few-body problem: light-front dynamics and Bethe–Salpeter equation. We show that implementing relativistic invariance leads to new qualitative properties, and that, even driven by the same interaction Lagrangian, both approaches provide different quantitative results, especially in three-body systems. The case of Bethe–Salpeter equation for computing electromagnetic form factors is discussed.     

Neutrino Mixing Matrix and Leptogenesis from Quantum Gravity

We consider non renormalization 1/M _x interaction term as a perturbation of the neutrino mass matrix. We find that for the degenerate neutrino mass spectrum. We assume that the neutrino masses and mixing arise through physics at a scale intermediate between Planck Scale and the electroweak scale. We also assume, above the electroweak breaking scale, neutrino masses are nearly degenerate and their mixing is bimaximal. The perturbation generates a non zero value of θ ₁₃, which is within reach of the high performance neutrino factory. In this paper, we find that the non zero value of θ ₁₃ due to Planck scale effects indicates the possibility of CP violation.     

Nonclassical Radiation from Two Atoms and Quantum Search Algorithms

We discuss the non-classical aspects of the radiation emitted from a system of two atoms. We first consider the radiation emitted from independently radiating quantum systems. If the atoms are excited by coherent light then the radiation exhibits the usual interference fringes in the far field as the point of observation is varied. By contrast,if the system is incoherently excited no interferences can be seen in the far held intensity pattern, 1. e. tne first order correlation function. However, if the second order correlation function is considered interferences appear even if the system is incoherently excited, i.e. even if the emitted photons are uneorrelated .This can be understood in terms of interferences between multiple pathways for quantum transitions as well as the detection induced entanglement. We show the non-classical nature of these intensity-intensity correlations. Such quantum interferences can be used for range of applications, i.e. for information processing or in applications to quantum search algorithms.We also consider the ease when the atoms are dose to each other so that the dipole-dipole interaction between them is significant. In this ease it is demonstrated that as a function of the detector position we can probe the decay either in the symmetric space or in the antisymmetrie space.     

Magnetic properties of CeSb and DySb from μSR

ZFSR experiments on CeSb and DySb reveal fast spin dynamics even in their magnetically ordered states below 16.2 and 9.5 K, respectively. Above these first order transitions both pnictides exhibit strong frequency shifts in TF pointing to some magnetic precursors. The signals below T _N show spontaneous rotating contributions. For CeSb several commensurately modulated antiferromagnetic phases containing paramagnetic sheets are confirmed. For DySb our data favor a CoO type structure in contrast to the MnO structure proposed from neutron diffraction.Part of this work was funded by the German Federal Minister for Research and Technology (BMFT) under contracts No 03-LI3-BRA and 03-KA2-TUM-4.     

ΛN and ΣN Interactions from Lattice QCD

We present our recent study on ΛN and ΣN (isospin I = 3/2) interactions by measuring Nambu–Bethe–Salpeter wave functions on the Lattice QCD. The lattice QCD calculation is performed by using the N _f  = 2 + 1 gauge configurations generated by PACS-CS collaboration together with employing an improved method to obtain potentials in lattice QCD simulations. For the ¹ S ₀ channel, the central ΣN (I = 3/2) potential and the central ΛN (¹ S ₀) potential are found to be very similar. For the spin triplet (³ S ₁?³ D ₁) channels, the central ΛN(³ S ₁?³ D ₁) potential is attractive while the central ΣN(I = 3/2, ³ S ₁?³ D ₁) potentials is repulsive. Tensor potentials, on the other hand, are rather weak in both ΛN and ΣN(I = 3/2) systems.     

Radium equivalent and annual effective dose from geological samples from Pedra – Pernambuco – Brazil

The natural radioactivity of an uranium-anomalous area utilized for agricultural activities in Pedra, Brazil, was monitored. For this, samples from the granite and calcium-silicate amphibole rocks underlying this area and also from samples of the soil derived from these rocks were collected and analyzed by high-resolution gamma spectrometry. The equivalent radium (Ra_eq) was used as a reference for estimating the rate of the effective equivalent dose. The average, minimum and maximum values for the samples were of 319.2 Bq kg^?1 (91.1–758.5 Bq kg^?1) for soil; 327.5 Bq kg^?1 (36.3–1624.0 Bq kg^?1) for granitic rocks and 70,124.5 Bq kg^?1 (16,979.6–147,159.0 Bq kg^?1) for the calcium-silicate amphibole rocks. An estimation of the external exposition was carried out based on the calculation of the parameters obtained.     

Cosmologies with Variable G and Λ from Action Principle

Cosmologies with variable G and are developed in this paper from an action principle, and some exact cosmological models are presented. These models indicate that the era of variable G and must have occurred, if at all, prior to other possible eras like radiation and dust.     

Networks Emerging from the Competition of Pullulation and Decrepitude

In real-world network evolution, the aging effect is universal. We propose a microscopic model for aging networks,which suggests that the activity of a vertex is the result of the competition of two factors: pullulatlon and decrepitude. By incorporating the pullulation factor into previous models of aging networks, both the global and individual aging effect curves in our model are single peaked, which agrees with the empirical data well. This model can generate networks with scale-free degree distribution, large clustering coefficient and small average distance when the decrepitude intensity is small and the network size not very large. The results of our model show that pullulation may be one of the most important factors affecting the structure and function of aging networks and should not be neglected at all.