K− absorption reactions from rest in deuterium

Quantitative agreement with the data on K⁻ d → NΛπ and NΣπ relative rates and spectra is found by solving a system of twelve Faddeev equations. The data imply that there is no stable bound state (second sheet pole above ΔN threshold) in the (ΣN, ΛN) system but do require a virtual state (fourth sheet pole) near the ΣN threshold.     

Threshold photoelectron spectrum of CO by electron attachment (TPSA)

The threshold photoelectron spectrum of CO is reported in the photon energy range from 14.0 eV (photoionization threshold) to 21 eV. The technique used is threshold photoelectron spectroscopy by electron attachment (TPSA). Vibrational levels of the X²Σ⁺ state are observed up to high quantum numbers (ν′? 12) and their population is found to be enhanced by resonant autoionization. Levels in the A²Π and B²Σ⁺ states are also observed. Here, the measured vibrational populations more closely follow Franck—Condon intensities, so that for these states direct photoionization is more important. Qualitative molecular-orbital arguments are given to make plausible the enhancements observed in CO⁺ and in previous measurements on N₂⁺.     

Selective effects of homogeneous and heterogeneous reactions in the system N21-CO

In the system N₂¹-CO, effects arising only from the reactions in the homogeneous phase have been isolated in a reactor with inert walls. After an induction period of 0.13 s, they involve a stationary rate of enhancement of N₂(B³Π_g) and N(⁴S) concentrations according to the reactions N₂(X¹Σ_g⁺)_v¹+CO→ CO(X¹Σ⁺)_v1 + N₂(X¹Σ_g⁺ and CO(X¹Σ⁺)_v1 + N₂(A³Σ_u⁺) → N (⁴S) + N(⁴S) + CO(X¹Σ⁺).In a reactor with active walls, both the above reactions in the homogeneous phase and heterogeneous reactions due to CO adsorbed on the walls are involved according to CO_ads + N₂(X¹Σ_g⁺)_{v1 ads or not} → CO(X¹Σ⁺)_v1 + N₂(X¹Σ_g⁺ and N(⁴S) + N(⁴S) + CO_ads → N₂(X¹Σ_g⁺) + CO(X¹Σ⁺)N(⁴S) + CO_ads → N₂(X¹Σ_g⁺) + CO(X¹Σ⁺). In this case, the rate of enhancement is not stationary. Furthermore, for cylindrical reactors with large diameters, the two types of reaction do not interact and their effects are additive.     

Hyperon-nucleon scattering (II). Anomalous thresholds

We calculate the discontinuities across the anomalous cuts in the s-channel of ΣN → ΣN and ΣN → ΛN, using (i) the method of analytic continuation of m_Σ² in the unitarity formula due to Mandelstam and Gribov, and (ii) the Cutcosky rule. The result should be useful for a more rigorous treatment of hyperon-nucleon scattering in the low-energy region, in particular, for the N/D formalism in the presence of anomalous thresholds.     

Phase-shift analysis of π N → K Σ

We have performed an energy-independent phase-shift analysis of πN → KΣ by analyzing differential cross-section and polarization data for the reactions π⁺p → K⁺∑⁺ and

at fifteen energies from threshold to 2137 MeV invariant mass. The single-energy solutions were linked by shortest-path methods with and without constraints implied by the Odorico zeros for the reaction π^?p → K⁺Σ^?. Similar to π^?p → KΛ it has been found that both isostates are dominated below 1900 MeV by resonances in the spin $\text{1}\text{2}$ waves. The F₃₇ resonance couples to KΣ with √x_πNx_KΣ= 0.04.     

Realistic Effective YN Interactions in Hypernuclear Models

The features of the new interaction model ESC08 in Λ N, Σ N, Λ Λ and Ξ N channels are demonstrated on the basis of the G-matrix theory.     

Diagnosis of OH radical by optical emission spectroscopy in a wire-plate bi-directional pulsed corona discharge

The emission spectrum of the molecule OH (A²Σ→X²Π, 0–0) during a high-voltage, bi-directional pulsed corona discharge consisting of a gas mixture of N₂ and H₂O in a wire-plate reactor has been successfully recorded under severe electromagnetic interference at atmospheric pressure. The relative vibrational populations and the vibrational temperature of N₂ (C, v′) have also been determined. Due to the difficulty of determining the exact overlapping spectral line shape function of the OH (A²Σ→X²Π, 0–0) and the Δv=+1 vibrational transition band of N₂ (C³Π_u→B³Π_g), a practicable Gaussian form is used for calculating the emission intensity of OH (A²Σ→X²Π, 0-0) and the Δv=+1 vibrational transition band of N₂ (C³Π_u→B³Π_g). The emission intensity of OH (A²Σ→X²Π, 0–0) has been evaluated with a satisfactory accuracy by subtracting the emission intensity of the Δv=+1 vibrational transition band of N₂ (C³Π_u→B³Π_g) from the overlapping spectra. The relative population of OH (A²Σ) has been obtained by the emission intensity of OH (A²Σ→X²Π, 0–0) and Einstein's transition probability. The influences of peak voltage, pulse repetition rate and O₂ flow rate on the relative population of OH (A²Σ) radicals have also been investigated. We found that the relative population of OH (A²Σ) rises with an increase in both the peak applied voltage and the pulse repetition rate. When oxygen is added to an N₂ and H₂O gas mixture, the relative population of OH (A²Σ) radicals decreases exponentially with an increase in added oxygen. The main physicochemical processes involved are also discussed in this paper.     

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.     

Infrared diode laser and millimeter-wave spectroscopy of the NCl radical: Vibrational and isotopic dependences of molecular constants

The infrared diode laser and millimeter-wave spectra of the nitrogen chloride radical in the X³Σ⁻ state have been observed in a DC glow discharge plasma of a N₂ and Cl₂ mixture, yielding spectroscopic information on ¹⁴N³⁵Cl up to v = 4 and ¹⁴N³⁷Cl up to v = 3. The observed infrared and millimeter-wave spectra have been simultaneously included in a least-squares analysis to determine Dunham coefficients for the vibrational and rotational energies and similar terms for the fine structure interactions. The analysis has shown that isotopic relations based on the Born-Oppenheimer approximation do not hold for the vibrational frequency, the rotational constant, and the spin-spin and spin-rotation interaction constants. It has been found that the first derivative of the spin-spin interaction constant with respect to the internuclear distance is correlated with the change in the equilibrium internuclear distance caused by the b¹Σ⁺ ← X³Σ⁻ excitation.     

High-precision laser and RF spectroscopy of the spin-rotation and HFS interactions in the X2Σ+ and B2Σ+ states of LaO

The spin-rotation and hyperfine interactions in the X²Σ⁺ and B²Σ⁺ electronic states of ¹³⁹La¹⁶O have been studied using Doppler-free laser-induced fluorescence and molecular-beam laser-rf double resonance. Observations were made for several values of v and many values of N, allowing evaluation of the principal interaction strengths and their N and v dependences for both the X and B states. The results are compared with earlier results for the isoelectronic system ¹³⁷Ba¹⁹F.     

The vacuum uv emission spectrum of the 15N22+ molecular ion

The vacuum uv emission of the ¹⁵N₂²⁺ ion has been recorded for the first time. Rotational analysis of two bands, analogous to those already observed in the case of the natural isotope, confirm their assignment to the D¹Σ_u⁺-X¹Σ_g⁺ (0, 0) and (1, 1) bands. More precise data are also obtained for the ³Σ_g^? state which perturbs ground state vibrational levels.     

Coupled KdV equations with multi-Hamiltonian structures

We present a large class of systems of N-equations which possess (N+1) purely differential, compatible Hamiltonian structures. Our generic equations are isospectral to [(Σ^N−1₀ε_iλ²ⁱ)∂²+Σ^N−1₀υ_iλ²ⁱ]ψ=λ^2Nψ, but our class also includes degenerate, nondispersive systems which are unrelated to this linear problem. Embedded in this class, for each N, there are N distinct coupled KdV systems. When N = 2 our class includes 3 known equations: dispersive water waves, Ito's equation and reduced Benney's equations. These equations are thus tri-Hamiltonian. We also present 2 examples of 3-component quadri-Hamiltonian systems, which generalise the above mentioned dispersive and nondispersive water waves.     

Two-channel separable potential model for the low-energy hyperon-nucleon interaction

A two-channel separable potential model is given such that the T-matrix is given in the form of a N/D matrix. This model is used to examine the relationships between the three different definitions for a resonance in the two-channel problem, particularly for a ³S₁ Λp resonance. In order to obtain a phenomenological hyperon-nucleon (YN) scattering T-matrix in the present model, a least-squares fit is performed to the existing available data for the $\text{I =}\text{1}\text{2}\text{YN}$ scattering cross sections and angular distributions at low energies using the s- and p-wave N/D solutions which carry sixteen independent parameters. Several solution sets of potential parameters are found, for which we can obtain good fits to the Λp → Λp, Σ^?p → Λn and ΣN → ΣN data, particularly to the cross-section data for these processes. The p-wave contributions are estimated, and particularly the possibility of p-wave YN resonances is pointed out for the solutions for which we do not assume a ³₁ Λp resonance.     

Interaction of Zn atoms in the 1 S and 3 P states with N2 molecules in the X 1Σ g + and A 3Σ u + states at moderate distances between the atom and molecule

An asymptotic method was used to derive analytical expressions for the matrix elements of interaction between the N₂ molecule in the X ¹Σ _g ⁺ and A ³Σ _u ⁺ electronic states and the Zn atom in the ¹ S and ³ P states. Quadrupole-quadrupole, dispersion, and exchange interactions were taken into consideration. The character of the set of diabatic vibronic potential energy surfaces of the system suggests that the energy transfer in the process N₂(A ³Σ _u ⁺ ) + Zn(¹ S) → N₂(X ¹Σ _g ⁺ ) + Zn(³ P) may prove to be rather effective.     

Diffraction dissociation of the proton into ΛK+ and (ΣK)+in π+ p interactions at 10.3 GeV/c

We observe a threshold ΛK⁺ enhancement in the reaction π⁺p → ΛK⁺π⁺ at 10.3 GeV/c. The production characteristics are very similar to those of the diffractive ΛK⁺ enhancement observed at the CERN ISR. The ΣKπ channels show no similar (ΣK)⁺ enhancement, as predicted by SU(6).     

A shock-tube measurement of the SiO(E1Σ+ − X1Σ+) transition moment

The sum of the squares of the electronic transition moments, Σ|R_e|², for the E¹Σ⁺ ?X¹Σ⁺ band system of SiO has been determined from absorption measurements conducted in the reflected-shock region of a shock tube. The test gas was produced by shock-heating a mixture of SiCl₄, N₂O and Ar, and the spectra were recorded photographically in the 150–230 nm wavelength range. The values of the Σ|R_e|² were determined by comparing the measured absorption spectra with those produced by a line-be-line synthetic spectrum calculation. The value of the Σ|R_e|² so deduced at an r-centroid value of 3.0 Bohr was 0.86±0.10 atomic units.     

High-resolution Fourier spectrometry of 15N2 infrared emission spectrum: Extensive analysis of the B3Πg-A3Σu+ system

The emission spectrum of the B³Π_g-A³Σ_u⁺ system of the ¹⁵N₂ molecule was recorded between 3500 and 12 500 cm⁻¹ with a high-resolution Fourier spectrometer. Twelve bands with 0 < v′ < 5 and 0 < v″ < 9 are analyzed. The molecular parameters of the B³Π_g and A³Σ_u⁺ states are obtained by a complete fitting procedure. Derived values of equilibrium constants are deduced; the Franck-Condon factors are calculated for the B-A system of ¹⁵N₂.     

Complete scissors mode strength in heavy deformed odd-mass nuclei: a case study of 165Ho and 169Tm

The low-energy dipole strength distributions in ¹⁶⁵Ho and ¹⁶⁹Tm have been studied in nuclear resonance fluorescence experiments at the S-DALINAC utilizing a Euroball Cluster detector. In the energy interval between 2.5 and 4.0 MeV, where the scissors mode is expected, 35 ground state transitions could be observed in ¹⁶⁵Ho and 53 in ¹⁶⁹Tm. Assuming M1 character for all these transitions corresponds to ΣB(M1) ↑= 1.54(23), μ_N² and ΣB(M1) ↑= 2.15(63), μ_N² for ¹⁶⁵Ho and ¹⁶⁹Tm, respectively. A statistical analysis is applied to the measured spectra which is capable of reconstructing the complete strength, including contributions of transitions below the observation limit, with the ratio between M1 and E1 excitations and their total strengths taken as an average over the even-mass neighbours. This results in summed M1 transition strengths of ΣB(M1) ↑= 3.54_−0.95^+0.75, μ_N² (¹⁶⁵Ho) and ΣB(M1) ↑= 3.36_−0.57^+1.00μ_N² (¹⁶⁹Tm). The large variations of the summed dipole strength and the fragmentation in other deformed odd-mass nuclei can be reproduced by the same statistical ansatz. The total low-lying M1 strength in heavy deformed odd-mass nuclei is in agreement with the findings in the neighbouring even-mass nuclides as well as with sum-rule predictions.     

Electron-vibrational energy exchange in collisions of electronically excited N2(A 3Σ u + ) molecules with Zn(X 1 S) atoms

The interaction matrix between the N₂ molecule in the X ¹Σ _g ⁺ and A ³Σ _u ⁺ states and the Zn atom in the ¹ S and ³ P states calculated earlier by the asymptotic method was used to find the rate constants for the electron-vibrational energy exchange N₂(A ³Σ _u ⁺ , v) + Zn(¹ S) → N₂(X ¹Σ ₈ ⁺ , v′) + Zn(³ P). The calculations were performed by the transition state method, and the probabilities of transitions between intersecting electron-vibrational terms of the system in motion along the reaction coordinate were determined by the Landau-Zener equation. The calculated electron excitation transfer constants between N₂(A ³Σ _u ⁺ , v = 1, 0) and Zn(¹ S) over the temperature range 300–900 K were on the order of 10^?11?10^?12 cm³/s.     

Quasielastic kaon knockout from a proton and momentum distribution of virtual kaons in the proton

The momentum distribution of kaons in the proton and the coupling-constant ratio fKΛN/fKΣN are determined on the basis of the ³P₀ quark model of meson-baryon coupling. The longitudinal cross section for kaon electroproduction is calculated. The results of the present study are compatible with available experimental data, but more detailed data on the longitudinal cross section would make it possible to refine the absolute values of the coupling constants fKΛN and fKΣN.