Tata Institute of Fundamental Research

About: Tata Institute of Fundamental Research is a education organization based out in Mumbai, Maharashtra, India. It is known for research contribution in the topics: Magnetization & Large Hadron Collider. The organization has 7786 authors who have published 21742 publications receiving 622368 citations. The organization is also known as: TIFR.

Anharmonic oscillator and the analytic theory of continued fractions

Abstract: We study anharmonic oscillators of the type $a{x}^{2}+b{x}^{4}+c{x}^{6}$ using the theory of continued fractions. Introducing a new set of coupling constants (depending on $a$, $b$, and $c$) in terms of which the associated difference equation simplifies, we write the Green's function of the theory in terms of an infinite continued fraction of the Stieltjes type, whose poles give the energy eigenvalues. We prove that this continued fraction converges where the corresponding perturbation series in the dominant coupling diverges. We obtain the analytic structure of the Green's function in the complex plane of this coupling constant. A scale transformation allows us to study the analyticity of the Green's function for $a{x}^{2}+c{x}^{6}$ oscillators in the energy plane.

Effect of γ-radiation on the structure and morphology of polyvinyl alcohol films

Abstract: The structure and morphology of polyvinyl alcohol (PVA) films, deposited from solution, was determined by using Infra Red Spectroscopy (IR), X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The films were irradiated with gamma rays for various doses up to 20 mrad. The color of the films changed to yellowish-brown after irradiation. The crystallinity percentage, as calculated from XRD and IR spectra, was found to decrease. Additional changes observed in IR absorption bands and XRD revealed the possibility of liberation of –H and –OH groups as well as scission of the main chain.

Quasiparticles in the superconducting state of Bi(2)Sr(2)CaCu(2)O(8+delta)

Abstract: Recent improvements in momentum resolution lead to qualitatively new angle-resolved photoemission spectroscopy results on the spectra of Bi(2)Sr(2)CaCu(2)O(8+delta) (Bi2212) along the (pi, pi) direction, where there is a node in the superconducting gap. We now see the intrinsic line shape, which indicates the presence of true quasiparticles at all Fermi momenta in the superconducting state, and lack thereof in the normal state. The region of momentum space probed here is relevant for charge transport, motivating a comparison of our results to conductivity measurements by infrared reflectivity.