• Volume 17, Issue 6

December 1981,   pages  445-514

• F bands in KCl-KBr mixed crystals

Gamma ray-induced F bands in melt grown mixed crystals of KCl and KBr are studied at room temperature. The effect of dislocations on F-centre density in mixed crystals has been discussed. In addition, the influence of composition of mixed crystals on F band parameters has been studied. The behaviour of observed F bands is correlated to local strained regions and to the configuration of F centre in mixed crystals.

• Air-exposure effect on the resistivity of thin bismuth films

A survey of previous studies on vacuum deposited metal films shows that in high frequency measurements, explicit reference to the effect of air-exposure is not made. The present work on bismuth films (in-situ and air-exposed) at dc and rf frequencies, carried out mainly to study the air-exposure effect, shows that in-situdc and rf and exposed rf all show nearly the same resistivity for thick continuous films. But air-exposed dc film resistances, when compared to in-situdc resistances, show that the grain boundary reflection coefficient, Rgin Mayadas-Shatzkes model changes from 0·2 to 0·6. This is shown to be due to the grain boundary oxidation. The result is substantiated by rf measurements.

• Volume compression of CuCl to 7 GPa

The unit cell volume of CuCl as a function of pressure has been measured up to 7 GPa (giga Pascals). The compression behaviour is quite normal. The analysis of the compression data gives 40·3±1·5 GPa for the bulk modulus of the zinc blende phase. The zinc blende phase transforms to a tetragonal phase at 5·5 GPa, the volume change associated with the transformation being 12%. A comparison of the bulk modulus of CuCl with those of CuBr and CuI indicates that an anomaly exists in this group.

• Gauge invariance and renormalization schemes in quantum chromodynamics

A general analysis of the Slavnov-Taylor identity connecting the triple gluon and ghost-ghost-gluon vertices and its consequences for two momentum subtraction (symmetric and asymmetric) renormalization schemes are given. It is shown that in the asymmetric scheme proposed in this paper the relation $$Z_3 Z_{1^{ - 1} } = \tilde Z_8 \tilde Z_{1^{ - 1} }$$follows directly from the identity for a simple and natural definition of the renormalization constants. Explicit one-loop expressions for the renormalization constants $$\left( {Z_1 ,Z_3 ,\tilde Z_1 \tilde Z_3 } \right)$$in an arbitrary covariant gauge, including quark masses are given in support of the general analysis.

• On light supernuclei

The possible existence of charmed analogues of the YN and light hypernuclear systems are investigated using phenomenological one-boson-exchange potential and the SU(4) symmetry. Bound light supernuclei such as C1N (I=3/2, J=0) and C1NN(I=2, J=1/2) C0NN (I=1, J=1/2, and I=0, J=1/2 or 3/2) are predicted with reasonable binding energies using Faddeev formalism for the three body systems.

• Schrödinger vs. dirac bound state spectra of $$Q\bar Q$$-systems and a plausible lorentz structure of the effective power-law potential-systems and a plausible lorentz structure of the effective power-law potential

It is shown that a non-relativistic power-law potential model for the heavy quarks in the form V(r)=Arv+V0, (A, ν&gt;0) acquires relativistic consistency in generating Dirac bound states of $$Q\bar Q$$-system in agreement with the Schrödinger spectroscopy if the interaction is modelled by equally mixed scalar and vector parts as suggested by the phenomenology of fine-hyperfine splittings of heavy quarkonium systems in a non-relativistic perturbative approach.

• Theoretical evaluation of the overall values of unnormalized discrepancy indices for truncated data in crystals obeying Wilson distributions

Theoretical expressions for the local values of six types of unnormalized R-indices are derived for an imperfectly related incomplete model of a crystal (centrosymmetric and non-centrosymmetric) with truncated data which is characterized by a truncation limit yt. These indices depend on the parameters σ1, D and yt. In the situations of practical interest (i.e., σ12&gt;0·3 and yt&lt;0·2) R-indices for the centro-symmetric case decrease as ytincreases while these for the non-centro-symmetric case remain more or less constant.

• Extensivity of entropy and modern form of Gibbs paradox

The extensivity property of entropy is clarified in the light of a critical examination of the entropy formula based on quantum statistics and the relevant thermodynamic requirement. The modern form of the Gibbs paradox, related to the discontinuous jump in entropy due to identity or non-identity of particles, is critically investigated. Qualitative framework of a new resolution of this paradox, which analyses the general effect of distinction mark on the Hamiltonian of a system of identical particles, is outlined.

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