• Volume 23, Issue 5

      November 1984,   pages  1-669

    • Velocity dependent inertial induction: An extension of Mach’s principle

      Amitabha Ghosh

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      In this article a model of inertial induction has been presented. According to this model the magnitude of the acceleration dependent inertia force comes out exactly as the product of the acceleration and inertial mass. The model also indicates that even uniform velocity gives rise to inertia force. However, the magnitude of the velocity dependent inertia force is exceedingly small but it causes a cosmological red shift whose order of magnitude is same as that of the observed values.

    • Superposition of special non-abelian potentials

      Sunil Kumar D C Joshi

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      The superposition of the non-abelian potentials of the formAμ=Aαμ+μ andBμ=Bγμ+bημ are considered and the necessary as well as the sufficient conditions are obtained. The significance of the conditions is discussed and the constrained isotopic spins of the perturbation potentials (μ,bημ) are shown to be necessary for the superposition of these potenitals.

    • Flip angle dependence in two-dimensional multiple quantum coherencenmr spectroscopy

      N Murali Y V S Ramakrishna K Chandrasekhar M Albert Thomas Anil Kumar

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      The multiple-quantum pathway description developed earlier for two-dimensional single-quantum correlation spectroscopy (cosy), is generalized and applied to the two-dimensional multiple-quantum transitions (2Dmqt) spectroscopy. The connectivity classes ofcosy are also generalized tomqt spectroscopy. The pathway description allows a straightforward method of computation of the flip angle dependence of the intensity of various peaks in two-dimensional correlation spectroscopy. It is shown that a variation of flip angle allows distinction between various classes and types of transitions, as well as optimization of experiment for selective detection of certain classes of peaks in 2D spectroscopy.

    • ΔT-window neutron spectrometer

      P S Goyal C L Thaper B A Dasannacharya

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      A high resolution neutron spectrometer making use of a ΔT-window filter for the analyser and time-of-flight technique for analysing incident neutron energy has been designed. The spectrometer will provide a continuously variable energy resolution ΔE from 40–50µeV at ∼ 5230µeV. The range of energy transfer allowed is −1450µeV to +2950µeV and the range of wavevector transferQ allowed is 0·82–3·06 Å−1. Depending on the resolution used, the counting rates are expected to vary from 28–60 × 103 counts/hr if one assumes 10% isotropic elastic scattering from the sample.

    • Infrared studies on ion irradiated quartz

      A K Sood V Umadevi R Kesavamoorthy G Venkataraman

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      Damage produced inα- and fused quartz bombarded with low energy (∼ 100 keV) D+, He+ and Ar+ ions, has been studied by observing the changes in their spectrum. Besides bulk reflectivity, the attenuated total reflection spectrum has also been studied, the latter with a view to obtaining the surface polariton frequencies. It is observed that for the same fluence, the changes following D+ irradiation are much higher compared to that for Ar+ irradiation. The variation of the surface polariton frequency inα-quartz with the damage energy deposited has the same trend as observed earlier for refractive index. Some annealing studies have also been performed in argon-irradiated samples. These studies indicate that whereas in fused quartz the damaged layer recovers completely, inα-quartz there is a residual amorphization even after annealing. A two-layer model is proposed which gives a reasonable simulation of the observedir properties.

    • X-ray determination of the Debye-Waller factors and Debye temperatures of AgCl and AgBr

      K Srinivas D B Sirdeshmukh

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      The integrated intensities of Bragg reflections are measured for AgCl and AgBr at room temperature using an x-ray powder diffractometer. The Debye-Waller factors and Debye temperatures are evaluated.

    • Thermal conduction through loose and granular two-phase materials at normal pressure

      R N Pande D R Chaudhary

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      The integrated theory derived for the lattice-type dispersions is modified and extended to estimate the effective thermal conductivity of loose and granular two-phase materials at normal pressure assuming an effective continuous media approximation. A comparison of calculated values ofλe with the reported experimental results over a wide range of loose and granular two-phase materials shows a good agreement.

    • Are weak vector bosons composite?

      S N Biswas S Rai Choudhury K Datta Ashok Goyal

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      Recentcern$$p\bar p$$ collider data on anomalousZ° events suggest, among other possibilities, a composite structure for the weak intermediate vector bosons. We present a short review of these developments and examine how far the scenario for weak interactions with such composite models of the weak vector bosons presents a viable alternative to the standard electroweak theory. In particular, we show how the scale of the dynamics underlying the composite structure is set by the magnitude of the weak mixing angle sin2θw and point out the possibility of accommodating the anomalous$$Z^ \circ - l\tilde l\gamma $$ decay events presently observed within this picture.

    • Charmonium and upsilon systems with fine-hyperfine splittings

      S N Jena T Tripati

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      We show that both charmonium and upsilon spectra can be simultaneously fitted by an effective non-coulombic power-law potential with lowest order relativistic corrections. The fine-hyperfine splittings of these spectra can be well understood without considering the short distance coulombic part of the potential as suggested byqcd, if the Lorentz structure of the central potential is taken as an almost equal admixture of vector and scalar gluon exchanges. With this model we make several specific predictions for the upsilon spectra which could hopefully be tested in the near future.

    • Superspace Ward identities in supersymmetric gauge theories

      Darwin Chang Asim Gangopadhyaya

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      In superspace formulation of supersymmetric gauge theories, gauge invariance requires an infinite set of identities between the infinite set of renormalization constants. Using Ward identities in superspace, the same is derived. These identities at one loop level are also demonstrated.

    • Optical anisotropy of some cholesteryl esters of fatty acids

      H S Subramhanyam Upkar Singh Hunjan

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      Assuming the Neugebauer relations to be valid we have made calculations with regard to the effective polarizabilities and hence the optical anisotropy in smectic and cholesteric mesophases of five cholesteryl esters of fatty acids. The variation of optical anisotropy as a function of temperature and the change in optical anisotropy as we pass from the lowest temperature in the smectic phase to the lowest temperature of the cholesteric phase are correlated with the number of C-C bonds in the alkyl end groups of the molecules. It emerges that the end groups do not contribute significantly to the effective optical anisotropy owing to the existence of rotational isomerism.

    • Operator method and eigenvalues of the triple-well anharmonic oscillator

      R K Roy Choudhury Barnana Ghosh

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      Using an algebraic technique based on the Lie algebra of the group SO(2, 1) the eigenvalues of the triple-well anharmonic oscillator are calculated for all ranges of the coupling constant. Approximate analytic formulas for the eigenvalues up to second order are given. The results obtained are compared with those of other authors.

    • A hermitian open-shell many-body perturbation theory for treating intruder states

      Azizul Haque Debashis Mukherjee

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      In this paper we have formulated an open-shell many-body perturbation theory (mbpt) that applies to an incomplete model space. The effective HamiltonianHeff generated in our theory is hermitian. We follow the resolvent-operator based time-dependent formulation ofmbpt of Banerjeeet al, and show quite generally that, by classifying the various determinants spanning the Hilbert space as model valence spaceP, virtual valence spaceR and virtual spaceQ, a diagrammaticmbpt satisfying size consistency can be developed. The chief new features of the theory are (i) manifest hermiticity ofHeff; (ii) presence of disconnected diagrams no part of which is a legitimate diagram (irreducible disconnected diagrams); (iii) presence of folded diagrams with components that may be irreducible disconnected diagrams; (iv) a consistent treatment of the variousn-valence sectors of the Hilbert space that may be interacting throughHeft if valence-holes are present—in particular a modified treatment of the core-valence separation. The generalisation afforded by the theory offers useful conceptual as well as computational advantages because the convergence difficulty encountered in a complete valence space formulation may be bypassed here by keeping the offending valence space determinants out of the model space. A brief critique of the developmentvis-a-vis the only other general model space development leading to a nonhermitianHeff is also given.

    • Isotope shifts in theA1 Π −X1 Σ+ system of PN molecule

      P Saraswathy G Krishnamurty

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      The emission spectrum of PN molecule was excited in an electrodeless microwave discharge in sealed tubes containing phosphorus, nitrogen and neon. Isotope shifts of several bands of theA1Π −X1Σ+ system were studied using nitrogen isotope. Vibrational assignments of several bands were confirmed.

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