Volume 34, Issue 2
February 1990, pages 91-171
pp 91-101 February 1990
A self-contained argument is given for the mass independence of the renormalization constants in the minimal subtraction scheme in dimensional regularization in a two mass theory (Yukawa theory). An extension to a theory containing more mass parameters seems straightforward.
pp 103-109 February 1990
We analyze the various inputs that go into computing the recently measured first moment of the proton spin structure functiong1p(x). The basic inputs are the various valence and sea quark polarisations and the gluonic contribution coming through axial anomaly. We show that the quark model predictions for valence quark polarisations, suitably modified to accommodate Bjorken sum rule, are consistent with measured value of moment of the spin structure function.
pp 111-115 February 1990
The potential between two12C nuclei in linear chain configuration has been calculated microscopically using the Ali-Bodmerα-α potential. This potential shows a pocket and compares well in the tail region with the phenomenological potential extracted before, from the data on the quasi-molecular resonances of the12C +12C system. This provides support to the diatomic like rotation-vibration picture of quasi-molecular states.
pp 117-122 February 1990
Non-perturbative Floquet method is used to investigate the interaction of strong linearly polarized light with He-atom. In the calculations, six lowest singlet target states and fifteen photon states are taken for absolute convergence. For allowed transitions, accurate oscillator strengths using configuration interaction wave-functions are used. A number of interesting features such as nonlinear effects at high intensities, line broadening, a dynamic Stark effect are obtained and explained.
pp 123-131 February 1990
The perturbation theory with non-spherical reference system is used for molecular fluid with angle-dependent square-well type potential. Simple analytic expressions are given for the thermodynamic properties such as the equation of state, excess free energy per particle, internal energy and internal heat capacity. The effects of anisotropy on the thermodynamic properties are discussed. The anisotropy effects increase with increase of density and decrease of temperature and depends on the anisotropy parameterx0.
pp 133-149 February 1990
The character of the ground state of the electron crystal—an electron gas with periodic density and/or spin density is investigated. Calculations for non-magnetic, ferromagnetic and anti-ferromagnetic electron crystals based on the Koster-Kohn variational principle for direct calculation of Wannier functions are presented. The Wannier function is approximated by a symmetrically orthonormalized Gaussian. The orbital exponent of the Gaussian is used as a variational parameter. The effect of the positive background is suitably taken into account. The results of our calculation support Wigner’s prediction of electron crystallization.
pp 151-156 February 1990
Indentations have been made on the (111) planes of CaF2, SrF2 and BaF2 at various temperatures up to 700°C. By etching the crystals, the indentation dislocation rosettes (IDRs) have been recorded and the relative hardness is estimated from the dimensions of the IDRs. The hardness of all these crystals falls with temperature according to the equationH=A exp(−BT). Dramatic changes are observed in the shape of the IDR at elevated temperatures indicating activation of new slip systems.
pp 157-163 February 1990
Ultrasonic absorption was measured in ortho and para hydroxy benzoic acid (OHBA and PHBA) in dioxan at room temperature for various solute concentrations. The variation of ultrasonic absorption in both solutions with the solute concentration showed two maxima, one at lower solute concentration and the other at higher solute concentration. The first maximum is explained as due to formation of hydrogen bonds between the O-H groups of OHBA and PHBA molecules and the oxygen of dioxan molecules and the second maximum as due to the COOH group of the OHBA/PHBA molecules and oxygen of dioxan molecules. In both systems the measured absorption is explained on the basis of Hall’s two-state model.
pp 165-171 February 1990
Nickel chloride was excited in a high frequency discharge source and the band at 3664 Å was photographed at an inverse dispersion of 0.59 Å/mm on a two metre plane grating spectrograph. The rotational analysis was carried out and the molecular constants of the upper state are reported. The rotational isotopic shifts due to37Cl support the rotational analysis. The electronic transition involved is identified to beβ2Δ5/2 →X12Δ5/2.
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