The ratio of the magnetic to the electric proton form factors in Quantum Chromodynamics

We propose a two parameter expression for the high momentum transfer behaviour of the ratio of proton form factors G_M(Q²)/Q_E(Q²) based on perturbation theory calculations in Quantum Chromodynamics. A fit to the present experimental data and its consistency with a previous fit to the high Q² behaviour of the Dirac form factor [1] is also discussed.     

Classical behaviour of the soliton density in Rb2ZnCl4 studied by 87Rb NMR

The temperature dependence of the soliton density n_s(T) which has been studied in Rb₂ZnCl₄ by ⁸⁷Rb NMR could be fitted to a classical formula using only one fit parameter. From our data we cannot confirm recent experimental results which yield a critical exponent $\text{1}\text{2}$ for the soliton density. The results are discussed with respect to the free energy where the soliton density acts as the order parameter. Moreover, couplings to other degrees of freedom, e.g. the elastic strains, are considered.     

Lattice model calculation of hugoniot curves and the grüneisen parameter at high pressure for the alkali halides

A seven parameter shell model of the interatomic forces in the NaCl lattice is used to make a detailed lattice dynamics calculation at arbitrary volume, for fourteen alkali halides. The calculated normal mode spectrum gives an explicit vibrational contribution to the pressure and the elastic constants in the quasiharmonic approximation. The seven parameters are chosen to fit low pressure ultrasonic data and the low and high frequency dielectric constants. Prediction of the Grüneisen parameter γ, (?lnγ/?lnV), and δ_s = (?1/βB_s)(dB_s/dT) are in reasonable agreement with experiment. The calculated γ decreases monotonically with volume. Calculated Hugoniots are in good agreement with experiment for NaCl, NaBr and NaI, and in fair agreement for LiBr, LiI and NaF.     

Pion and kaon form factors and heavy vector mesons

A zero parameter model of analytic pion and kaon form factors with supplementary dynamical constraints is presented. Contrary to the general belief the predicted form factors have a t^?2 behaviour and fit the pion space-like data excellently. Some properties of heavy vector mesons are predicted and discussed.     

The systematics of nuclear single-particle states of nuclei with 50 ≦ NZ ≦ 82

The depth of the local Woods-Saxon potential corresponding to the experimental binding energies of the single particle states in gdhs nuclei has been parametrized as a function of the mass number A and the symmetry parameter (N?Z)/A. A typical spread of 200 keV of the calculated values of the potentials from the best fit curve was obtained. The implication of the pairing correlations are discussed.     

Phenomenology of asymptotically free theories in deep inelastic scattering: (I). Electron and muon scattering

We calculate the predictions of asymptotically free theories for deep inelasric scattering using a straightforward Mellin transform technique which uses a minimum of theoretical assumptions. Parameterizing the quark and anti-quark distributions functions, we fit all the available μ and e scattering data. We investigate the sensitivity of the theory of the (almost) unknown gluon distributions and the choice of scaling variable. The best fit uses the formalism of Georgi and Politzer for the 1/Q² terms with a quark gluon coupling constant g²/4π ～ 1 at Q² = 1 (GeV/c)². (Equivalently the scale parameter Λ is 500 MeV/c.) Good fits are also found in simpler models using x, x′ or ξ as scaling variables. The best value of Λ depends strongly on the choice of scaling variable.     

A study of the dalitz plot in the decay KL0 → π+π−π0

The results are presented of an analysis of 4709 fully reconstructed K_L⁰ → π⁺π^?π⁰, observed in a hydrogen bubble chamber. The data fit to a linear π⁰ energy spectrum to give a slope parameter g = 0.610 ± 0.022.     

Binding energy of benzoate ions on alumina

We present a simple statistical mechanical model for the adsorption of molecules from solution onto solid surfaces. This model improves our understanding of the liquid doping technique commonly used in inelastic electron tunneling spectroscopy (IETS) sample preparation. Using this model we obtain an excellent two parameter fit to the experimental data of Langan and Hansma for the surface concentration vs solution concentration for the adsorption of benzoic acid on alumina from a water solution. This fit gives the density of binding sites N = 1.0 × 10¹⁵ cm^-2 and the binding energy ? = 1.0eV for the system.     

Antiferromagnetic susceptibility of RbMnF3. Evidence for a temperature dependence of the exchange constant

The perpendicular susceptibility of an RbMnF₃ single crystal has been measured from T = 6?295 K (T_c = 83 K). The data are compared with theoretical predictions for the s.c. Heisenberg model (high-temperature series expansion and spin-wave theory at T = 0). The fit to theory reveals a temperature dependence of the exchange constant, that can be related to the variation of the lattice parameter with temperature as reported in the literature.     

Measurement and analysis of the ν2 band of H2S: Comparison among several reduced forms of the rotational Hamiltonian

The frequencies of 123 lines between 1080 and 1260 cm^?1 in the ν₂ band of H₂S were measured with a tunable diode laser and a grating spectrometer. Ground- and upper-state molecular constants appropriate to Watson's A reduced Hamiltonian in the I^r coordinate representation were obtained from a simultaneous fit of the ν₂ band data and previously measured H₂S rotational microwave frequencies. This fit had a standard deviation comparable to the experimental uncertainties. The A reduced Hamiltonian in the III^r representation, however, was found to fit the data very poorly. The large value of the transformation parameter s₁₁₁ calculated for the A reduced Hamiltonian in the III^r representation confirms that this result is due to the slow convergence of this particular reduced Hamiltonian.     

Adiabatic bond charge model for the phonons in A3B5 semiconductors

The adiabatic bond-charge model is extended to describe phonon dispersion curves and elastic properties in A³B⁵ semiconductors. Asymmetry of the bond-charge position and of the force constants involving them is found to be the main consequence of ionicity. A six-parameter model provides a good fit to the experimental data for GaAs, GaSb and InSb. A small seventh parameter describing weak second-neighbor interactions is needed in GaP. Trends in the force-constant parameters are discussed.     

Observation of short-order clustering effect in Cd1−xHgxTe

The infrared lattice-vibration reflection spectra of Cd_1-xHg_xTe (0?x?0.8) solid solution were measured. For the composition x from 0.1 to 0.6 on the top of the CdTe-like band one can observe considerable fine structure. To account for its nature the short-range clustering of the cations (Cd, Hg) around the anions (Te) characterized by parameter β was supposed. A good fit of the calculated and measured reflectively spectra was obtained provided the clustering parameter β = 0.6.     

<Emphasis Type="Italic">K</Emphasis><Subscript><Emphasis Type="Italic">e</Emphasis>3</Subscript> Decay Studies in the OKA Experiment

Recent results from OKA setup concerning form factor studies in K_e3 decay are presented. About 5.25 M events obtained for decays of 17.7 GeV/cK⁺ are selected for the analysis. The linear and quadratic slopes for the decay form factor f₊(t) are measured: λ'₊ = 2.95 ± 0.022 ± 0.018 × 10 ^-2 for the linear slope fit and λ₊ = 2.611 ± 0.035 ± 0.028 × 10 ^-2, λ"₊ = 1.91 ± 0.19 ± 0.14 × 10 ^-3 for the quadratic one. The scalar and tensor contributions are compatible with zero. Several alternative parametrizations are tried: the Pole fit parameter is found to be M _V = 891 ± 3 MeV; the parameter of the dispersive parametrization is measured to be Λ₊ = 2.458 ± 0.018 × 10^-2.     

The ABC effect and chiral-bag-model form factors

We investigate the ABC effect in the reaction n+p → d+(ππ)⁰ using the chiral lagrangian of Weinberg in the tree approximation. Chiral-bag-model form factors are used for the vertices. We obtain cross sections as a function of energy for deuteron scattering angles θ_d = 0° and 10.5°. The results are compared with the latest experimental measurements. The fit to the absolute value of the cross section is obtained taking the bag radius R as a free parameter; the fitted value of R turns out to be that expected in the light of previous studies in the framework of chiral bag models. The ABC effect is almost completely accounted for in terms of the lowest-order diagrams.     

Grüneisen parameter and thermal expansion of V3Si and V3Ge

The Grüneisen parameter and lattice thermal expansion of the A-15 compounds V₃Si and V₃Ge at room temperature are evaluated on the basis of the method due to Brugger and Fritz [1] from the third order elastic constants reported earlier [2]. The calculated values are compared with available experimental values and are found to fit satisfactorily.     

Some remarks on the significant character of spectroscopic constants (triatomic linear molecules)

The influence of the H_v term on the values of the other spectroscopic constants B_v and D_v has been analyzed. The questions specifically considered are: When is it necessary to introduce it in the fit to reproduce satisfactorily the wavenumbers for the rotational structure of a given vibration-rotation transition? Even though this constant is not a significant parameter (H > 3δH, δH being the standard deviation) is it necessary to introduce it for extrapolations to very high J values? As a result of these considerations, it has been possible to define an experimental; protocol to determine “correct” spectroscopic constants.     

Superconductivity in thin tin films: Fluctuation effects

The excess electrical conductivity in thin tin films due to thermodynamic fluctuations above T_c has been measured as a function of temperature and sheet resistance R_ns of films which varied from 0.2 Ω/? to 120 Ω/?. Results have been compared with the Aslamazov-Larkin, Maki-Thompson and Patton theories. It is found that among three the Maki-Thompson theory gives a better fit to experimental data. The pair breaking parameter a fitting parameter in the M-T theory, is found to behave linearly with R_ns of films and is given by ? ? 9x10^?3 + 1.02x10^?2R_ns for R_ns ≤ 12 Ω/?.     

Critical finite-size scaling of magnetization distribution function for Baxter–Wu model

The distribution function P_L(m) of the order parameter for the Baxter–Wu model is studied using blocks of linear dimension L of a larger triangular lattice. At a given temperature, we use the Metropolis algorithm for the generation of a sample of configurations on the triangular lattice. The similarities and differences of this distribution with the usual cases of Ising lattices are investigated. We conclude that the present model obeys, at the critical temperature, a finite-scaling law with the known critical exponents as expected. However, our numerical data strongly indicate that the analytic form of the scaling function does not conform to the corresponding function for the usual Ising model. An analytic expression that gives a good fit is presented.     

Measurement of the phase coexistence curve in the critical region of a phenol-water binary mixture

We have performed measurements of the phase-coexistence curve of a binary mixture of phenol and water in the vicinity of the critical mixing temperature and calculated the critical exponent β of the order parameter. A least square fit to the 21 data points in the temperature range T_c?T<900 mdeg leads to a value of β equal to 0.334.