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By
Ramachandran, R
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An attempt is made to see how much of chiral symmetry is contained in dual models for pseudoscalar mesons. The chiral constraints are found to be contained in dual models as either dynamical restriction or kinematical factors. At the phenomenological level there is no serious inconsistency.
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By
Gopalakrishnan, P S; Manohar, H
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6 Citations
The oxidation of orthorhombic Sb_{2}O_{3}, valentinite, to orthorhombic Sb_{2}O_{4}, cervantite, has been shown by single crystal xray diffraction techniques to be a topotactic reaction. The orientation relationships between the two lattices have been determined by making use of a hybrid crystal. It has been found that the individual axes in the two oxides are parallel. The two crystal structures have been compared in the appropriate orientation and their close similarity has been established. The shifts of the individual atoms in valentinite during the process of oxidation have been calculated to be not more than 0·6 Å. It has been established that the reduction of cervantite to valentinite also takes place topotactically.
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By
Sen Gupta, N D
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The object of this paper is to point out that the hypothesis of decaying states,i.e., states with amplitude having a factor e^{γt} (γreal) is not compatible with the wave equation with a hermitian hamiltonian. An attempt has been made to obtain the expression for relative population density in general. It is shown that the usual expressions for the transition rates, which are proportional to time, may be obtained for a very restricted interval of time.
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By
Bhandari, Rajendra
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1 Citations
The role of the observer in physical theories in the sense of the observer’s viewpoint determining prominent features of the observed phenomena is discussed with reference to the problem of irreversibility and quantum measurement, the latter being closely related to the problem of classical behaviour of quantum systems. A completely subjective interpretation of irreversibility is proposed. It is claimed that irreversibility belongs only to phenomena as observed by a restricted observer who must project all phenomena on a restricted subset of the set of all possible states. The possibility of a completely unrestricted observer who does not see irreversibility is discussed.
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By
Nityananda, Rajaram
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1 Citations
A medium with periodic variation of the dielectric tensor is considered. It is assumed to have helical symmetry. The response to external fields is described by the most general linear law—that is, by the methods of spatial dispersion theory. The propagation of a wave is described by a mutually consistent electric field and polarisation. It is shown that the presence of the medium produces changes in the polarisation and wave vector of the electric field, and the selection rules governing these changes are derived from symmetry. The results generalise previous work on the Oseen model for a cholesteric liquid crystal to the case when the molecules are not perpendicular to the helical axis. This can arise in an external magnetic field applied along this axis.
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By
Ananthakrishna, G; Suger, J Eduardo
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We consider a class of Hamiltonians for a system of one localized spin1/2 particle per lattice site with the total spin as a good quantum number. We introduce a set of conditions in the form of a hypothesis relating the subpartition function, which is the partition function defined by the subset of energies with a specific value of spin. If the equality in the hypothesis is satisfied, then the system undergoes a phase transition as a consequence of YangLee theorem. As an application, we estimate the bounds on the spectrum of the Heisenberg Hamiltonian.
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