An anharmonic force field for SO3

An anharmonic force field for SO₃ based on the valence force model has been investigated. The results of extending the model to include some further estimated cubic interaction potential constants have also been investigated. The phenomenological parameters calculated from both model force fields agree with those few values which have been experimentally determined. A calculation of the inertia defect has been made, and thus the value of C₀ has been determined. The equilibrium structure has been determined to be: $\text{r}{}_{\mathrm{e}}\text{= 1.4184 ± 0.0010}\text{A}\text{?}$.     

The use of central pair potentials in the lattice dynamics of yttrium

A phenomenological model for the study of lattice dynamics of h.c.p. metals has been developed on the basis of a 5-neighbour central pair potential between ions and an approximate electron-ion interaction. The dispersion curves of yttrium derived from this model present a good agreement with the experimental curves and the deviations which are most pronounced near the zone boundary in (01$\text{1}$0) direction are nowhere larger than six per cent.     

Remarks concerning the nuclear surface and curvature energy

The $\text{A}\text{1}\text{3}$ term in the nuclear mass formula is studied. The curvature correction is investigated within the framework of the energy density formalism; the compression term is evaluated from a phenomenological point of view. The results are in fair agreement with the droplet model values obtained by Myers and Swiatecki.     

NN scattering below 300 MeV due to quark rearrangement annihilation and one-boson exchange

A microscopic $\text{N}\text{N}$ potential is presented where the annihilation effect is described by the quark rearrangement model and the one-boson-exchange contribution is further added. Gross features of $\text{p}\text{p}$ scattering observables are described by the potential with modification by a phenomenological repulsion at short distances.     

Three-body forces in the lattice dynamics of some hcp metals

The consideration of paired interionic forces cannot explain the lattice dynamics of Be, Tb and Ho. In the present work, a phenomenological force constant model has been developed which considers three-body forces in addition to the usual forces of paired character. This approach explains the correct ordering of dispersion branches and the experimental degeneracy of the K-point in Be, Tb and Ho. Further good agreement is found between the theoretical curves and the neutron data of three high symmetry directions $\text{[0001], [01}\text{1}\text{0] and [11}\text{2}\text{0]}$ for all the three hcp metals.     

The soft acoustic phonon mode and its relation to the martensitic transformation in In-Tl alloys

Phonon dispersion curves for indium and f.c.t. and f.c.c. indium-thallium alloys have been calculated using the optimised model potential theory. The presence of a soft acoustic mode along [110], polarised [1$\text{1}$0] has been established. The closer the alloy composition is to the phase boundary, the softer this mode becomes: $\text{1}\text{2}\text{(C}{}_{11}\text{–C}{}_{12}\text{)}$ tends towards zero, in agreement with experimental ultrasonic velocity data.     

The NN interaction in a quark model with quark-antiquark excitations

Quark-antiquark excitations inherent in the quark-gluon interaction have been incorporated into a quark model of the nucleon to study the effects of such excitations on the NN interaction within the framework of the resonating group method. The three-quark (3q) components of a single nucleon are augmented by ($\text{3}\text{q}\text{)(}\text{q}\text{q}$) excitations with the 24 possible spin, isospin, color combinations for the energetically lowest p-wave relative motion function. Quark exchange kernels are then calculated for the two-nucleon system described by these improved nucleon internal functions; and these exchange kernels are converted to phase-shift-equivalent effective NN potentials by the Wigner-transform WKB technique. The off-shell qq? pair-creation terms are derived from the one-gluon exchange diagrams in the Breit approximation in analogy with the derivation of the qq and qq? potentials. The parameters of the interaction are chosen to be consistent with the experimental Δ-N mass difference, the nucleon-vector-meson coupling constants, and the nucleon magnetic moments. Within these constraints, the predicted amplitudes of the ($\text{3}\text{q}\text{)(}\text{q}\text{q}$) components of the nucleon internal functions have been shown to be insensitive to the precise values of the model parameters. In particular, they pass the crucial test of being insensitive to very large changes in the magnitude of the confinement potential constant which is a necessary ingredient of the model. The qq? excitations lead to the following effects in the S-wave NN potentials: (i) The repulsive core heights of the simple 3q-3q model are greatly reduced but retain their strong essentially linear energy dependence, with numerical values very similar to those of the short-range phenomenological terms of the Paris potential. (ii) The effective potentials have acquired an attractive part in the 0.8-1.5 fm range. However, this attraction is too weak to bind the deuteron or fit the extreme low-energy S-wave phase shifts.     

A model for baryonium

The spectrum of $\text{qq}\text{q}\text{q}$ hadrons examined in a quark-gluon model yields two types of state both of which have small mesonic widths and may be associated with baryoniums. One type (T-diquonium) has normal hadronic widths into $\text{B}\text{B}$, while other (M-diquonium) is narrow and decays into $\text{B}\text{B}$ only reluctantly, preferring if possible to decay by cascade. The experience gained from ordinary hadron spectroscopy, plus some new phenomenological observations, allow one to predict the spectrum and properties of both types in considerable detail. The result bears close resemblance to present experiment.The existence of narrow M-diquonium states follows only from hidden colour, and if established would be a major triumph for the concept. It would be, however, only the first example of a quite general phenomenon which may well develop into a whole new branch of hadron spectroscopy.     

Deformed Hartree-Fock calculations not restricted to very short range effective interactions

Some results of deformed Hartree-Fock calculations for s-d shell nuclei are presented. A phenomenological effective interaction due to Gogny has been used which consists of two Gaussians plus a delta interaction depending on the density as $\text{?}{}^{\mathrm{<mtext>1</mtext><mtext>3</mtext>}}$. The trend of deformation properties in this region is rather well reproduced.     

Phenomenological description of the reaction K−p→K10(890)(π−p) using a dual fermion model

Using the Neveu-Schwarz-Ramond model as a starting point, attempts have been made to construct a phenomenological dual amplitude for the reaction $\text{K}{}^{\mathrm{?}}\text{p}\text{→}\text{K}{}^{10}\text{(890)(π}{}^{\mathrm{?}}\text{p}\text{)}$. The amplitude contains trajectories of both natural and unnatural spin-parity in the exchange channel as well as N_α, N_γ and Δ trajectories in the production channel. Furthermore, it has the correct Regge behaviour in both meson and fermion channels. Reasonable agreement between the predictions and the data with respect to differential cross sections and density matrix elements has been found.     

Gluinos and lower bounds for squark and slepton masses from jet plus missing-pT events at the pp collider

On the basis of a detailed phenomenological analysis, combined with the minimal N = 1 supergravity model, it is shown that the jet plus missing-p_T events at the p$\text{p}$ collider can only be explained by relatively light gluinos ($\text{m}\text{g}\text{?}\text{< m}\text{q}\text{?}$ with a mass of about 40 GeV. The resulting squark and slepton masses are then found to be $\text{q}\text{?}\text{> 50}$ GeV and $\text{m}\text{e}\text{?}\text{> 35}$ GeV.     

Elastic scattering of polarised helions from 40,44,48Ca

A phenomenological analysis of the polarised helion elastic scattering data from the ^44,48Ca targets, as well as a re-analysis of the ${}^3\text{He}\text{+}{}^{40}\text{Ca}$ data, has been carried out. It is demonstrated that the spin-orbit potential required to reproduce the polarisation distribution is not unique. Although spin-orbit potentials with the anomalously small diffuseness parameters (a_s ～ 0.2 fm) are found, there are others with larger values (up to 1.05 fm) which can also account for the data in this target mass range. The average strength of the “anomalous” spin-orbit potentials for the three targets is found to be consistent with the values deduced for the proton and deuteron scattering, provided the potential family with the real volume integral per particle pair in the region of 330 MeV · fm³ is considered physically meaningful.     

Magneto-microwave Kerr effect in high conductivity Mn-Zn ferrites

Magneto-microwave Kerr effect has been studied both theoretically and experimentally on two samples of high conductivity Mn-Zn ferrites for one of which ($\text{λ4πM}{}_{\mathrm{s}}\text{ω}$) was greater and for another less than unity. The experimental measurements have been made with the help of a microwave interferometer. The technique is useful for determination of effective FMR linewidth in samples of larger dimensions. It is found that Rado's theory is unable to interpret these results for any of the samples, while Green and Sandy's phenomenological theory is able to do so for the sample to which it is applicable, viz. the one with $\text{λ4πM}{}_{\mathrm{s}}\text{ω}\text{< 1}$.     

Effective densities in local-density approximations of the nucleon-nucleon effective interaction

The choice of an effective local density for a finite-range density-dependent effective interaction is considered. The effect appears in the second-order perturbation energy for a density-independent bare force. Analysis of this energy shows that other finite-nucleus effects are more important than the uncertainties arising from the use of a c.m. density, or arithmetic or geometric mean density. The latter uncertainties are found to be $\text{1}\text{4}\text{?1}\text{MeV}\text{/A}$ for most nuclei. Since the actual uncertainties in fitted phenomenological interactions are only a fraction of these, we feel that any of these local densities can be used without introducing large errors.     

Multiple coulomb excitation of 167Er

The ground-state rotational band in ¹⁶⁷Er has been investigated through multiple Coulomb excitation with a 160 MeV ³⁵Cl beam. Excited states up to $\text{25}\text{2}{}^{\mathrm{+}}$ were established by measuring γγ coincidences and γ-ray angular distributions. Gamma-gamma angular correlations were also measured. Nuclear lifetimes of levels up to spin $\text{23}\text{2}$ have been determined from Doppler-broadened γ-ray lineshapes, and B(M1) and B(E2) values of intra-band transitions deduced. Considerable signature dependence was observed for level energies and M1 transition probabilities. A Coriolis band-mixing calculation was carried our for comparison with the experimental results. The measured M1 transition probabilities are compared to calculations based on a particle-rotor model, a cranking model, and a microscopic model with quantum-number projection.     

Small transverse momentum distributions in hard processes

The effects of soft gluon brehmsstrahlung on the k_⊥ distributions of μ pairs produced in hadron-hadron collisions are studied using the Block-Nordsiek method. At moderate energies we obtain a good fit to present experimental data by adjusting the values of two phenomenological parameters. At quite large energies the predictions are independent of specific values assigned to the parameters and the whole p_⊥ distribution, including $\text{p}{}_{\mathrm{\perp }}\text{? 0}$, turns out to be computable.     

What is the relativistic generalization of a linearly rising potential?

Recent progress in summing graphs of non-Abelian gauge theories focuses attention on certain manifestly Lorentz-invariant classical action-at-a-distance theories, whose solution allows for the construction of field-theoretic Green functions in the WKB approximation. The sum of graphs is of QED type, except that the gluon propagator is modified to incorporate the renormalization-group-invariant charge $\text{g}\text{(k)}$. The purely phenomenological choice $\text{g}{}^2\text{～ k}{}^{\mathrm{?2}}$ is equivalent non-relativistically to a linearly rising potential and yields a fully relativistic classical action-at-a-distance theory with exactly soluble circular orbits, whose Bohr quantization yields an asymptotic approximation to the poles of the Green function. One finds asymptotically linear Regge trajectories, but other phenomenological aspects are not as promising when only a linearly rising potential is used (in common with other phenomenological studies). As a redeeming feature, there do not appear to be any obvious pathologies of the sort familiar from string theories and ad hoc generalizations of linearly rising potentials.     

Hyperbolicity conditions for the Lorenz model

It was shown earlier by Bunimovich and Sinai that the Lorenz Model has a natural invariant measure if the so-called hyperbolicity conditions hold. In this paper we represent results of a numerical verification of the hyperbolicity conditions for the Lorenz model with the values of the parameters $\text{б = 6}$, r = 28, $\text{b =}\text{8}\text{3}$.     

The kinetics of the photolysis of thin films of lead iodide

The kinetics of the photolysis of thin films of PbI₂ have been followed using a quartz crystal microbalance method. Rate as a function of temperature, light intensity and wavelength has been determined. The influence of grain size and gaseous ambient has also been investigated. Three ranges of kinetics were identified. Initial; associated with nucleation and surface chemical reactions. Intermediate; associated with photolysis without the intervention of optically absorbing product, gives $\text{(}\text{?θ}\text{?t}\text{)}{}_{\mathrm{T}}\text{,λ,I ∝ T}$. Terminal; attenuation due to lead particles, gives $\text{(}\text{?θ}\text{?t}\text{)}{}_{\mathrm{T}}\text{,λ,I ∝ t}{}^{\mathrm{<mtext>?</mtext><mtext>1</mtext><mtext>2</mtext>}}$.Results show that iodine is generated at the solid/vacuum interface and lead is generated in the bulk. Photolysis is described by phenomenological equations involving bulk and surface recombination of hole/electron pairs plus photolysis. A mechanism is proposed in which the rate determining step is anion vacancy diffusion from the surface, the activation energy for photolysis and anion vacancy diffusion being the same.