• Volume 9, Issue 5

      November 1977,   pages  441-544

    • Green’s functions for spin half field theory in Rindler space

      B R Iyer Arvind Kumar

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      The solutions of Dirac equation in different regions of the complete extension of Rindler space are obtained near the event horizons and in the asymptotic limits. Continuity of these solutions across the event horizons is established. The Green’s functions are written down in the two causally disconnected regions, continued in the future (F) and past (P) regions using the techniques a la Boulware and a consistent scheme of Green’s functions in all regions is exhibited.

    • On effectiveness of Morse and Lippincott potential functions forA andX states of MgH

      G K Patel B I Sheth

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      Molecular properties like potential curve,r-centroids, dissociation energy for theA2II-X2Σ band system of MgH are studied using Morse and Lippincott functions. Calculations for potential curve and dissociation energy indicate that the Lippincott function is not very appropriate forA andX states of MgH.r-centroids calculated using graphical as well as numerical methods agree well with each other. A smooth relationship between wavelength andr-centroid is obtained.

    • Optical colours and polarization of a model reflection nebula. III. Composite and mixture of grains in the nebula with the star in the rear

      G A Shah

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      The colour differences between the star and the associated reflection nebula and polarization caused by core mantle grains and mixture of grains have been given. They are based on homogeneous plane-parallel slab-model of the nebula with the star in the rear. The composite particles in the form of concentric spheres consist of homogeneous core of graphite, silicate or SiC and homogeneous mantle of ice. The effect of varying the core and mantle radii has been studied. The mixtures of grains composed of ice, silicate, graphite and SiC in various proportions have also been considered. Each of these grain species has been considered with exp(−a3) type of size distribution function. The wavelength dependent indices of refraction have been used throughout.

    • Liquid crystals of disc-like molecules

      S Chandrasekhar B K Sadashiva K A Suresh

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      Thermotropic mesomorphism has been observed in pure compounds consisting of simple disc-like molecules, viz., benzene-hexa-n-alkanoates. Thermodynamic, optical and x-ray studies indicate that the mesophase is a highly ordered lamellar type of liquid crystal. Based on the x-ray data, a structure is proposed in which the discs are stacked one on top of the other in columns that constitute a hexagonal arrangement, but the spacing between the discs in each column is irregular. Thus the structure has translational periodicity in two dimensions and liquid-like disorder in the third.

    • Some consequences of neutral current systematics

      T Das V Gupta

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      Two kinds of general consequences of the ΔS=0 weak hadron neutral current independent of a gauge model are presented. Firstly are results which depend on the quark parton model. These involve bounds among neutrino inclusive cross-section and a bound onQ(Z, N) in terms of these inclusive cross-sections. Secondly are results which are independent of the quark-parton model and depend only on the SU(3) structure of the most general ΔS=0 neutral current. These tests of isopin and speciallyU-spin properties of the current are given forv+Nv+hadron+anything,v+Nv+baryon+meson ande+e→baryon+anti-baryon. In addition some conjectures are made with regard to the semi-inclusive neutrino-reactions using the quark parton model.

    • Representation mixing and the ideal description of mesons

      S K Bose

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      Representation mixing of meson states is considered with particular reference to the 1 ←→ 15 mixing in SU(4). The 16 meson states are assigned to the representation (4*, 4) of a non-chiral group SU(4) ⊗ SU(4), whose factors are related by charge-conjugation. Mass formula, mixing angles and electromagnetic mass shifts are rigorously derived. Connection of the present formalism with conventional quark model is pointed out and generalisations to higher groups SU(n) ⊗ SU(n) as well as to higher representations, are indicated.

    • Asymptotic bounds on pion form factor

      M K Parida N Giri

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      A technique recently developed for inelastic electron proton scattering is applied for inelastic electron pion scattering. It is found that all the derivatives of off-shell form factor of pion nears=mπ2 and for largeQ2 are bounded from above, provided that the dispersion relation for the form factor requires no more than one subtraction. The elastic pion form factor is bounded by [lnQ2]c/Q2, wherec is any positive constant.

    • Dual charged solution in curved space-time

      R Ramachandran V M Raval

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      A dual charged solution carrying both electric and magnetic charge is formulated in SU(2) × U(1) gauge theory without making use of the topological characteristics of Higgs fields. When Dirac quantisation condition is imposed, two consequences follow: (i) Weinberg angle is restricted to the value sin2θ = 1/2 and (ii) the solution cannot have fractional electric change, but must have integer items the basic electric charge of the theory. The infinity inherent in the theory is removed at the classical level by the use of gravitational effects by obtaining the same solution in the curved space-time. The resultant metric is of Reissner-Nordström form.

    • Search for superheavy elements in monazite from beach sands of South India

      S S Kapoor V S Ramamurthy M Lal S K Kataria

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      Monazite minerals obtained from beach sands of South India were examined for the presence of superheavy elements with photon-induced x-ray fluorescence method. The accumulated data of a number of runs each of several days duration do not show any convincing peaks above the background at the expected locations for superheavy elements which are above the present sensitivity of detection of about 10 ppm by weight for element 126. However, some intriguing features pertaining to structures in the x-ray spectra around 27 keV were observed, which are of interest for further investigations.

    • Gas-liquid phase transition II: The van der Waals’ models

      A C Biswas

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      On the basis of a recently proposed theory of first order phase transition we discuss (i) the exact equation of state in the critical region and (ii) examine the van der Waals’ gas model.

    • Reflectance spectra and thermoluminescence of alkali halides coloured in an electrodeless discharge

      S V Moharil B T Deshmukh

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      Microcrystalline powders of NaCl, KCl and KBr are coloured in electrodeless discharge. Reflectance and TL studies of these coloured powders are reported. It is concluded that colouration of powders can be understood by considering them as an admixture of perfect and imperfect lattices, and differs from that of single crystals. It is suggested that some of the descrepancies reported on TL data may be due to such a difference. Further, it is shown that a better correlation can be had if TL data are presented along with the corresponding optical measurements. Adoption of such a procedure may help to remove the descrepancy in TL data.

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