Spectrum and damping in quadrupolar biquadratic systems (S=32)

Using the diagrammatic technique for Stevens operators the spectrum and the damping of elementary excitations for the doublet-doublet biquadratic systems are calculated in the $\text{(}\text{1}\text{z}\text{)}{}^1$ approximation.     

Excitation spectrum and T=0 dynamics of the one-dimensional planar spin-12 ferromagnet

The T=0 dynamics of the one-dimensional $\text{S}\text{=}\text{1}\text{2}$ ferromagnet with planar exchange anisotropy is studied by finite-chain calculations and a Green function approach. We demonstrate that the excitation spectrum relevant for appropriate low-T inelastic neutron scattering experiments is much more complex than predicted by linear spin-wave theory. It includes two continua and a set of discrete branches. Some of the low-lying excitations predicted by rigorous calculations, on the other hand, are shown to contribute no spectral weight to the T=0 dynamic structure factor S_zz(q,ω). We provide quantitative results for the spectral-weight distribution in S_zz(q,ω) at T=0 from bound states and continuum states, including a detailed analysis of the singularity in S_zz(q,ω) at the lower band edge. Further evidence is found for the prediction that some T=0 critical properties of the planar $\text{S}\text{=}\text{1}\text{2}$ ferro- and antiferromagnet are governed by exponents which depend continuously on the planar anisotropy.     

The U(612) supersymmetric limit of the interacting Boson-Fermion Model

The $\text{U(}\text{6}\text{12}\text{)}$ dynamical supersymmetry of the Interacting Boson-Fermion Model, appropriate for nuclei where the odd nucleon can occupy the single-particle orbits $\text{J =}\text{1}\text{2}\text{,}\text{3}\text{2}\text{,}\text{and}\text{5}\text{2}$ is analyzed. The subgroup structure of $\text{U(}\text{6}\text{12}\text{)}$ is discussed and the generators and Casimir operators of these subgroups are given. In each of the three dynamical symmetries of $\text{U(}\text{6}\text{12}\text{)}$ the energy formulas, reduction rules, and wave functions are obtained and closed expressions for E2 transition rates and one-nucleon transfer intensities are derived. Examples of $\text{U(}\text{6}\text{12}\text{)}$ symmetries are presented.     

The decay D(1865)→eνK1(890) and the right-handed current

The possible existence of a right-handed current in the charm sector is investigated by studying the principal D_?3 mode: $\text{D}\text{→}\text{e}\text{ν}\text{K}{}^1\text{(890)}$. Explicit expressions are given for the energy spectra of both K¹ and e as well as for their angular correlation. It is emphasized that the most sensitive model-independent test of the helicity property of the current is provided by the angular correlation rather than by the electron energy spectrum.     

Analysis of the Ã1A″ ← X̃1A′ electronic transition in thiocarbonyl chlorofluoride

The visible absorption spectrum of thiocarbonyl chlorofluoride, ClFCS, in the region 5000 to 3000 Å has been observed under conditions of high resolution in the vapor phase and has been assigned to the $\text{A}\text{?}{}^1\text{A″(nπ}{}^1\text{) ←}\text{X}\text{?}{}^1\text{A′}$ and $\text{a}\text{?}{}^8\text{A″(n, π}{}^1\text{) ←}\text{X}\text{?}{}^1\text{A′}$ electronic transitions. All six fundamental modes have been assigned for both the upper and lower singlet electronic states. From the observed splittings of the even-odd quanta of ν₆′ in the spectrum the barrier to inversion in the $\text{A}\text{?}{}^1\text{A″}$ state has been evaluated to be 1556.0 ± 45 cm^?1.     

20Ne + n → 21Ne(T = 32) resonances

$\text{T =}\text{3}\text{2}$ resonances in ²¹Ne have been studied in measurements of the total neutron cross section of ²⁰Ne using the 190 m neutron time-of-flight facility of the Karlsruhe Isochronous Cyclotron. The high time-of-flight resolution of 6.6 ps/m enabled the study of sharp $\text{T =}\text{3}\text{2}$ resonances in ²¹Ne with an effective energy resolution of up to 4000. Five $\text{T =}\text{case3}\text{2}$ levels have been observed as sharp resonances allowing the precise determination of total width Λ, partial decay with Λ_no and resonance energy E_R. The c.m. resonance parameters of the first $\text{T =}\text{3}\text{2}$ state in ²¹Ne are E_R = 2098.6 ± 0.3 keV, Λ = 2.2 ± 0.5 keV and Λ_no = 0.21 ± 0.05 keV. Upper limits for the partial decay widths are deduced for those $\text{T =}\text{3}\text{2}$ levels which do not appear as resonance anomalies. A search for additional $\text{T =}\text{3}\text{2}$ states was undertaken. The resonance energies are discussed in the framework of the isbobaric mass multiplet equation. The decay widths are compared with shell-model predictions of isospin mixing and the systematics of isospin-non-conserving particle decays.     

A t-channel isospin analysis of the chew-low plot for NN → N(Nπ) interactions at 5.7 GeV/c

A new approach to the t-channel isospin analysis of ZN → Z′(Nπ) reactions is presented. This approach, useful for $\text{Z = N,}\text{N}\text{, K}{}^{\mathrm{?}}$ when only five independent sets of data are availables, is used to analyse data of $\text{N}\text{N →}\text{N}\text{(Nπ)}$ reactions obtained in a $\text{p}\text{p →}\text{N}\text{N}\text{π}$ experiment at $\text{5.7}\text{GeV}\text{/c}\text{and a}\text{p}\text{d →}\text{N}\text{Nπp}{}_{\mathrm{s}}$ experiment at 5.5 GeV/c. the t behaviour of the different isospin exchange amplitudes, suggests their exchange mechanism production. The mass spectrum, M_πN, of the contributions produced by exchanged isospin I_ex = 1, shows enhancements corresponding to N(1490) N(1670) and Δ(1230) isobars, while the mass spectrum for I_ex = 0 presents only a large bump at ～1350 MeV commonly identified as N¹(1400).     

High-temperature expansion for the longitudinal susceptibility of the spin-12 XY model

The exact high temperature series expansion for the longitudinal susceptibility of the spin-$\text{1}\text{2}\text{XY}$ model is given. An expansion for a related quantity, the reduced susceptibility, is also obtained by noting a simple relationship between the two susceptibilities. Both series are nondivergent. The reduced susceptibility is useful for evaluating time-dependent properties of the XY model.     

A LEED crystallographic analysis for the Rh(111)-(3 × 3)30°-S surface structure

An intensity analysis with low-energy electron diffraction is reported for the $\text{(}\text{3}\text{×}\text{3}\text{)30°}$ surface structure obtained by the adsorption and presumed dissociation of H₂S on the (111) surface of rhodium. Intensity-versus-energy curves were measured with a video LEED analyser for nine diffracted beams at normal incidence, and comparisons made with the renormalised forward scattering method for four different types of structural models in which the metal atoms remain in their regular bulk positions. The best correspondence between the experimental and calculated intensities occurs with sulphur atoms adsorbed in the “expected” 3-coordinate adsorption sites. The reliability index proposed by Pendry is minimised with S atoms 1.53 Å above the topmost metal layer; this corresponds to nearest-neighbour RhS bond distances equal to 2.18 Å. Comparisons are made with structural data available for related systems, and with the predictions of a model analysis of surface bond lengths given recently by one of the authors.     

Time-resolved studies of 32 ω0 harmonic emission from laser-produced plasmas

New observations of the time-resolved spectrum of $\text{3}\text{2}$ ω₀ harmonic emission from plasmas produced with neodymium laser light indicate that stimulated Raman scattering replaces the two-plasmon instability as the principal source of $\text{ω}{}_0\text{2}$ plasmons when the plasma density scale length becomes sufficiently large.     

The adsorption of sulphur on Pd(111) I. A LEED analysis of the (2 × 3)R30° S adsorbate structure

The adsorption of sulphur on the Pd(111) surface is studied by low energy electron diffraction (LEED). Four different adsorbate structures are identified. LEED intensity analyses are performed for the clean surface and for the ordered initial adlayer, i.e. the $\text{(}\text{3}\text{×}\text{3}\text{)}\text{R}\text{30°}\text{S}$ adsorption phase. It is found that the sulphur atoms occupy threefold-symmetric hollow sites, with a SPd chemisorption bond length of 0.222±0.003 nm.     

Measuring the P-odd asymmetry in electroproduction of the δ(32, 32 resonance at low energies

We show that measurements of the P-odd asymmetry in the reaction $\text{e}{}^{\mathrm{?}}\text{+}\text{N}\text{→}\text{e}{}^{\mathrm{?}}\text{+δ(}\text{2}\text{2}\text{,}\text{3}\text{2}$ at low energies might determine the combination $\text{α}\text{～}\text{+(1.0–1.2γ}\text{β}\text{～}$ of the isovector phenomenological couplings, characterizing the parity nonconserving electron-quark neutral current interaction at presently accessible energies. They may provide also a very accurate determination of the parameter sin²θ_W of the standard electroweak gauge theory.     

Resonance magnetic field shift induced by electric field for the +12→-12 transition relativistic approach

The resonance magnetic field shift induced by an electric field for the $\text{+}\text{1}\text{2}\text{→-}\text{1}\text{2}$ transition has been interpreted using a relativistic spin motion equation. Two examples are reported.     

On the extra factor 12√π in the Kramers approximation

Two exactly solvable models—the double oscillator model and the associated harmonic oscillator model for which the Kramers approximation taken in the Gaussian approximation has an extra factor $\text{√}\text{π}\text{2}$-are discussed. A quantum mechanical derivation of the Kramers approximation without the Gaussian approximation is given.     

Radiative decays of the Jψ and evidence for a new heavy resonance

The three photon final state produced in e⁺e^? collisions has been measured at the mass of the $\text{J}\text{ψ}$ resonance using the nonmagnetic part of the double arm spectrometer DASP. The decays $\text{J}\text{ψ}\text{→ ηγ, η'γ}$ and π^oγ were observed and their branching ratios are given. A four standard deviation signal was observed in the γγ mass spectrum at a mass of (2.83 ± 0.03) GeV. An upper limit is given for the direct decay $\text{J}\text{ψ}\text{→ 3γ}$.     

The Ã1A″ ← X̃1A′ electronic transition in formyl chloride,CHClO

The ultraviolet absorption spectrum of formyl chloride has been recorded under conditions of modest resolution, 0.75 nm/mm, and long pathlengths, 96 m. The 314- to 269-nm spectrum proved to have well-defined vibrational fine structure and was assigned to the electron promotion, $\text{n → π}{}^1$. A comparison of the spectra of CHClO at 25 and ?78°C with CDClO led to the assignments: pseudo-origin, ν₂, ν₄, ν₅, and ν₆; $\text{32754.7}\text{32775.3}$, $\text{1153.8}\text{1092.0}$, $\text{633.6}\text{633.4}$, $\text{306.3}\text{303.1}$, and $\text{779.5}\text{566.5}\text{cm}{}^{\mathrm{?1}}$ for $\text{CHClO}\text{CDClO}$, respectively. A fit of the 6⁰, 6², 6³, and 6⁵ levels to those generated from a Gaussian-quadratic model potential yielded a barrier height of 1608.8 cm^?1 and an out-of-plane angle of 48.6° for the $\text{A}\text{?}$ state.     

New measurements of the n2P12,32 energy levels of Cs(I)

The energies of the $\text{n}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(7 ≤ n ≤ 13)}$ and $\text{n}{}^2\text{P}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{(7 ≤ n ≤ 27)}$ levels of CsI have been redetermined photographically from high resolution absorption measurements of the principal series lines $\text{6}{}^2\text{S}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{? n}{}^2\text{P}{}_{\mathrm{<mtext>J</mtext>}}$X. The new data disagree significantly [ ≈0.13 cm^-1] with the values given in the NBS-Tables of Moore¹ which are taken from a paper by Kratz.² By means of an extended Ritz-formula, the ionization energy of CsI was found to be 31406.46±0.03 cm^-1, which is, within the limit of uncertainty, in agreement with the data of Kleiman,³ Eriksson et al.,⁴ Bockasten,⁵ and Eriksson and Wenåker.⁶     

Approaches to the gravitational spin-32 axial anomaly

The $\text{spin}\text{-}\text{3}\text{2}$ axial anomaly is discussed from various points of view. Two consistent theories for a $\text{spin}\text{-}\text{3}\text{2}$ field interacting with gravity are considered: supergravity and a real quantized $\text{spin}\text{-}\text{3}\text{2}$ field in a classical gravitational background. The Feynman graph method, the zeta function regularization method, the point splitting method and the topological method all yield the same result for the latter theory, in agreement with that first found by Christensen and Duff.     

Effect of the final state interaction in the reaction γ + 4He → p + p + n + n

It is shown that the effect of the final state interaction in the reaction $\text{γ +}{}^4\text{He}\text{→}\text{p}\text{+}\text{p}\text{+}\text{n}\text{+}\text{n}$ is very significant. It is established that the two-nucleon photoabsorption mechanism is responsible for the four-body photodisintegration of ⁴He, not the single-nucleon photoabsorption.     

Energies of the n2S12 and n2D32,52 states of Cs

Using the technique of Doppler-free two-photon spectroscopy the energies of the n²S_{$\text{1}\text{2}$} (12 ? n ? 35) and n²D_{$\text{3}\text{2}$,$\text{5}\text{2}$} (11 ? n ? 48) states of CsI have been measured with a thermionic detector. The absorption spectrum of molecular iodine was used as a reference giving us a total estimated accuracy of about 2 × 10^-7. Taking also into account the energies of the 7–11 ²S_{$\text{1}\text{2}$} and 5 and 6 ²D_{$\text{3}\text{2}$,$\text{5}\text{2}$} states measured by other authors and using an extended Ritz-formula we found the ionization limit to be E_i = 31406.468 ± 0.006 cm^-1.