Frequency measurements in the b <Superscript>3</Superscript>Π(0<Subscript>u</Subscript><Superscript>+</Superscript>) - X <Superscript>1</Superscript>Σ<Subscript>g</Subscript><Superscript>+</Superscript> system of K<Subscript>2</Subscript>

Absolute transition frequencies of the b ³Π(0_u ⁺) - X ¹Σ_g ⁺ system of K₂ were measured in a molecular beam with Lamb dip absorption spectroscopy applying a frequency comb from a femtosecond pulsed laser. Both, K atoms and K₂ molecules are present in the beam and are expected to interact by collisions. The atoms can be deflected optically out of the beam, and thus the collision rate between K atoms and K₂ molecules is changed by about an order of magnitude. The molecular transition frequencies for low collisional rate are compared with those for high one. Limits for the collisional frequency shift within the beam are determined.     

Form factors,branching ratio and forward–backward asymmetry in B→K<Subscript>1</Subscript>ℓ<Superscript>+</Superscript>ℓ<Superscript>-</Superscript> decays

We study long-distance effects in the rare exclusive semileptonic decays B→K₁ℓ⁺ℓ^-, where K₁ is the axial vector meson. The form factors describing the meson transition amplitudes of the effective Hamiltonian are calculated using the Ward identities, which are then used to calculate the branching ratio and the forward–backward asymmetry in these decay modes. The zero of the forward–backward asymmetry is of special interest and provides us with a precision test of the standard model.     

Revisiting B<Superscript>+</Superscript>→X(3872)+K<Superscript>+</Superscript> in pQCD assigning to X(3872) 2<Superscript>3</Superscript>P<Subscript>1</Subscript> charmonium

We revisit the B⁺→X(3872)+K⁺ in the pQCD approach assigning to X(3872) a 2³P₁ charmonium state. In this theoretical framework all the phenomenological parameters in the wavefunctions and Sudakov factor are a priori fixed by fitting other experimental data; therefore, there hardly are any free parameters in the whole numerical computations. Our results are larger than the upper bound set by the BABAR measurements. PACS 13.20.He; 12.38.Bx; 13.60.Le     

Description of torsional motion in ionic complexes ArH<Stack><Subscript>3</Subscript><Superscript>+</Superscript></Stack> and ArD<Stack><Subscript>3</Subscript><Superscript>+</Superscript></Stack>

An algebraic model that describes the internal dynamics of the ionic complexes ArH₃⁺ and ArD₃⁺ in the ground electronic-vibrational state taking into account the torsional motion of the structure of identical hydrogen nuclei is constructed by symmetry-group chain methods. It is important that the correctness of this model is only limited by the correctness of the choice of geometric symmetry of the internal dynamics of the ionic complex.     

Analysis of (π K<Superscript>+</Superscript>) and (K<Superscript>-</Superscript>, K<Superscript>+</Superscript>) hypernuclear production spectra in distorted-wave impulse approximation

We study the hyperon-nucleus potential with distorted-wave impulse wave approximation (DWIA) using the Green's function method. In order to include the nucleon and hyperon potential effects in Fermi averaging, we introduce the local optimal momentum approximation of target nucleons. We can describe the quasi-free Λ , Σ and Ξ production spectra in a better way than in the standard Fermi-averaged t -matrix treatments.     

Luminescence in Dy<Superscript>3+</Superscript> and Eu<Superscript>3+</Superscript> Activated K<Subscript>3</Subscript>Al<Subscript>2</Subscript>(PO<Subscript>4</Subscript>)<Subscript>3</Subscript>

The Dy³⁺ and Eu³⁺ activated K₃Al₂ (PO₄)₃ phosphors were prepared by a combustion synthesis. From a powder X-ray diffraction (XRD) analysis the formation of K₃Al₂ (PO₄)₃ was confirmed. In the photoluminescence emission spectra, the K₃Al₂(PO₄)₃:Dy³⁺ phosphor emits two distinctive colors: blue and yellow whereas K₃Al₂(PO₄)₃:Eu³⁺ emits red color. Thus the combination of colors gives BYR (blue–yellow–red) emissions can produce white light. These phosphors exhibit a strong absorption between 340 and 400 nm which suggest that present phosphor is a promising candidate for producing white light-emitting diodes (LED).     

Isotopomer selective optimization of <Superscript>39</Superscript>K<Superscript>85</Superscript>Rb<Superscript>+</Superscript> and <Superscript>41</Superscript>K<Superscript>87</Superscript>Rb<Superscript>+</Superscript> using optimal control

We report on isotope selective three-photon ionization of two isotopomers of KRb by applying evolution strategies. The particularity of this experiment is based on the high resolution phase and amplitude modulation of the fs-laser pulses provided by a 2 × 640 pixel pulse shaper. The optimization in a closed feedback loop performed with spectrally broad pulses centered at 840 nm shows high enhancements of one isotopomer at the expense of the other isotopomer and vice versa. From the optimal laser field we aim to gain details about the selective ionization sequence and the wavepacket evolution on the involved vibrational states.     

Exclusive B→K<Subscript>1</Subscript>ℓ<Superscript>+</Superscript>ℓ<Superscript>-</Superscript> decay in model with single universal extra dimension

Decay rate and forward–backward asymmetries in B→K₁ℓ⁺ℓ^-, where K₁ is the axial vector meson, are calculated in the universal extra dimension (UED) model. The dependence of these physical quantities on the compactification radius R, the only unknown parameter in UED model, is studied, and it is shown that the zero of the forward–backward asymmetry is sensitive to the UED model; therefore they can be a very useful tool to establish new physics predicted by the UED model. This work is briefly extended to B→K^*l⁺l^-.     

Direct evidence of substituent clustering in lower valent K<Superscript>+</Superscript> modified PbZrO<Subscript>3</Subscript> by high-resolution Z-contrast imaging

The distribution of substituents in lead zirconate (PZ) modified by K⁺ (PKZ) has been studied by high-resolution Z-contrast imaging. Pronounced intensity variations were observed between various Pb columns, giving direct evidence that a number of columns had higher concentrations of (K⁺) substituents. High-resolution Z-contrast imaging was also performed in La⁺³-modified lead zirconate titanate (PLZT) for comparison. PACS 61.72.Ff; 77.84.Dy; 68.37.Lp; 68.55.Ln     

Na<Superscript>+</Superscript>/K<Superscript>+</Superscript> selectivity in the formation of ion pairs in aqueous solutions

The integral equations of liquids (RISM) and molecular dynamics method were used to calculate the mean force potential for the SO₃ and COO hydrophilic groups and the CH₃ hydrophobic group in the acetate, methyl sulfonate, and hydrosulfate anions, which form ion pairs with sodium and potassium cations in water. The carboxyl group selectively binds sodium ions from solutions containing Na⁺ and K⁺ ions, in spite of their equal charges, because the potassium ion experiences stronger steric hindrances near this group compared with sodium. The biophysical consequences of the revealed selectivity are discussed.     

Molecular dynamics study of the reaction C<Subscript>3</Subscript> + H <Subscript>3</Subscript><Superscript>+</Superscript>

Both a quantum molecular dynamic method and high level ab initio calculations (MP2, CCSD(T)) have been used to investigate the mechanism of the C₃ + H₃⁺ reaction, which is part of the ion chemistry in interstellar clouds. Furthermore statistic initial orientations in collision simulations have been set up in order to determinate reaction cross-sections and rate coefficients of all occurring reaction channels. Our analysis shows that the revealed mechanism is strongly determined by dynamic effects.     

Study of K<Superscript>*</Superscript><Subscript>0</Subscript>(1430) and a<Subscript>0</Subscript>(980) from B→K<Superscript>*</Superscript><Subscript>0</Subscript>(1430)π and B→a<Subscript>0</Subscript>(980)K decays

We use the decay modes B→K^* ₀(1430)π and B→a₀(980)K to study the scalar mesons K^* ₀(1430) and a₀(980) within the framework of perturbative QCD. For B→K^* ₀(1430)π, we perform our calculation in two scenarios for the scalar meson spectrum. The results indicate that scenario II is more favored by the experimental data than scenario I. The important contribution from annihilation diagrams can enhance the branching ratios by about 50% in scenario I and about 30% in scenario II. The direct CP-asymmetries in B→K^* ₀(1430)π are small, which is consistent with the present experiments. The predicted branching ratio of B→a₀(980)K in scenario I differs from the experiments by a factor of 2, which indicates that a₀(980) cannot be interpreted as q̄q.     

Low-spin states in <Superscript>182</Superscript>Os and K<Superscript>π</Superscript> = 0<Superscript>+</Superscript>, 2<Superscript>+</Superscript> excited bands

Excited states in ¹⁸²Os were populated by the β⁺/EC decay of ¹⁸²Ir following mass separation. Gamma-ray and conversion electron spectroscopy techniques were employed. Monopole (E0) contributions were determined in transitions populating the ground-state band. A systematic study of the low-spin structures in the Os isotopes is presented and a detailed analysis in the framework of a microscopic configuration mixing approach is performed.     

Luminescence of Tl<Superscript>+</Superscript> ions in a KZnF<Subscript>3</Subscript> crystal

The luminescence spectra of a KZnF₃: Tl⁺ crystal are investigated in the energy range from 4.75 to 5.9 eV at temperatures of 10–300 K upon excitation into the A absorption band (5.7–6.3 eV). At T=300 K, the luminescence spectra exhibit an intense band with a maximum at 5.45 eV, which is attributed to single Tl⁺ ions substituted for K⁺ ions. The 5.723-eV intense narrow band observed at T<20 K is assigned to the ³Γ_1u-¹Γ_1g zero-phonon transition, which is weakly allowed by the hyperfine interaction. The luminescence decay is studied as a function of temperature. The main characteristics of the luminescence spectra are adequately described in terms of the semiclassical theory based on the Franck-Condon principle and the Jahn-Teller effect for an excited sp configuration of the Tl⁺ ion with the use of the parameters obtained earlier from analyzing the absorption spectra of the system under investigation.     

Kinetics of Rb<Stack><Subscript>2</Subscript><Superscript>+</Superscript></Stack> and Rb<Superscript>+</Superscript> formation in laser-excited rubidium vapor

We have studied the formation of the molecular ion Rb₂⁺ and the atomic ion Rb⁺. These are created in laser excited rubidium vapor at the first resonance, 5s–5p and 5p-nl transitions. A theoretical model is applied to this interaction to explain the time evolution and the laser-power dependence of the population density of Rb⁺ and Rb₂⁺. A set of rate equations which describe: the temporal variation of the population density of the excited states; the atomic ion density; and the electron density, were solved numerically under the experimental conditions of Barbier and Cheret. In their experiment the Rb concentration was 1×10¹³cm⁻³ and the laser power was taken to be 50–500 mW at vapor temperature = 450 K. The results showed that the main processes for producing Rb₂⁺ are associative ionization and Hornbeck-Molnar ionization. The calculations have also showed that, the atomic ions Rb⁺ are formed through the Penning Ionization (PI) and photoionization processes. Moreover, a reasonable agreement between the experimental results and our calculations for the ion currents of the Rb⁺ and Rb₂⁺ is obtained.      

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.     

Structure of 2<Subscript>1,2</Subscript> <Superscript>+</Superscript> states in <Superscript>132,134,136</Superscript>Te

Starting fromthe Skyrme interaction f_ together with the volume pairing interaction, we study the g factors for the 2_1,2⁺ excitations of ^132,134,136Te. The coupling between one- and two-phonon terms in the wave functions of excited states is taken into account within the finite-rank separable approximation. Using the same set of parameters we describe the available experimental data and give the prediction for ¹³⁶Te, g(2₁⁺) = ?0.18 in comparison to +0.32 in the case of ¹³²Te.     

The use of quantum-correlated D<Superscript>0</Superscript> decays for φ<Subscript>3</Subscript> measurement

We report the results of the Monte Carlo study of the method to determine the CKM angle φ₃ using Dalitz plot analysis of D⁰ produced in B^±→DK^± decay. Our main goal is to find the optimal strategy for a model-independent φ₃ extraction. We find that the analysis using decays of CP-tagged D mesons only cannot provide a completely model-independent measurement in the case of a limited data sample. The procedure involving binned analysis of B^±→DK^± and ψ(3770)→(K⁰ _Sπ⁺π^-)_D(K⁰ _Sπ⁺π^-)_D decays is proposed which, in contrast, allows not only to reach the φ₃ precision comparable to an unbinned model-dependent fit, but also provides an unbiased measurement with currently available data. PACS 11.30.Er; 12.15.Hh     

III. Electron-impact dissociative ionization of C<Subscript>2</Subscript>H<Stack><Subscript>2</Subscript><Superscript>+</Superscript></Stack> and C<Subscript>2</Subscript>D<Stack><Subscript>2</Subscript><Superscript>+</Superscript></Stack>

The dynamics of cold atoms in conservative optical lattices obviously depends on the geometry of the lattice. But very similar lattices may lead to deeply different dynamics. In a 2D optical lattice with a square mesh, it is expected that the coupling between the degrees of freedom leads to chaotic motions. However, in some conditions, chaos remains marginal. The aim of this paper is to understand the dynamical mechanisms inhibiting the appearance of chaos in such a case. As the quantum dynamics of a system is defined as a function of its classical dynamics – e.g. quantum chaos is defined as the quantum regime of a system whose classical dynamics is chaotic – we focus here on the dynamical regimes of classical atoms inside a well. We show that when chaos is inhibited, the motions in the two directions of space are frequency locked in most of the phase space, for most of the parameters of the lattice and atoms. This synchronization, not as strict as that of a dissipative system, is nevertheless a mechanism powerful enough to explain that chaos cannot appear in such conditions.