Lattice bosons in quartic confinement

We present a theoretical study of bose condensation of non-interacting bosons in finite lattices in quartic potentials in one, two, and three dimensions. We investigate dimensionality effects and quartic potential effects on single boson density of energy states, condensation temperature, condensate fraction, and specific heat. The results obtained are compared with corresponding results for lattice bosons in harmonic traps.Comment: revised version, 11 pages including figures, accepted in EPJ

Agrarian distress and rural livelihoods : a study in Upputhara Panchayat, Idukki District, Kerala

This study examines the impact of agrarian distress on the different socio-economic groups, the strategies of livelihood adopted by households and the local institution in shaping these strategies. The study is based on the data collected from in-depth socio-economic enquiries conducted in Upputhara Panchayat in Idukki District. An important conclusion of the study is that the strategies of livelihood framed in response to a shock could vary across households depending on the extent of their asset ownership. Households in Upputhara achieved diversification of livelihoods in three major ways: through diversifying their cropping pattern, through diversifying their local occupations and through migration. The study showed that (a) in formulating coping strategies, households benefited from increased access to a number of public institution created through public action in earlier years; (b) access of households to the different welfare institutions was declining in recent years; and (c) the livelihood systems of people remained extremely vulnerable. Obviously, strengthening the livelihood systems of households would require sustaining their livelihood assets and income by reversing these state policies and making effective of the functioning of the local institutions like the Panchayat. Key words: Agrarian Distress, Livelihood Risks, Coping Strategies , Kerala JEL Classification: Q, Q 0

Bose-Einstein condensate in a quartic potential:static and dynamic properties

In this paper, we present a theoretical study of a Bose-Einstein condensate of interacting bosons in a quartic trap in one, two, and three dimensions. Using Thomas-Fermi approximation, suitably complemented by numerical solutions of the Gross-Pitaevskii equation, we study the ground sate condensate density profiles, the chemical potential, the effects of cross-terms in the quartic potential, temporal evolution of various energy components of the condensate, and width oscillations of the condensate. Results obtained are compared with corresponding results for a bose condensate in a harmonic confinement

Polaron cross-overs and d-wave superconductivity in Hubbard-Holstein model

We present a theoretical study of superconductivity of polarons in the Hubbard-Holstein model. A residual kinematic interaction proportional to the square of the polaron hopping energy between polarons and phonons provides a pairing field for the polarons. We find that superconducting instability in the d-wave channel is possible with small transition temperatures which is maximum in the large to small polaron cross-over region. An s-wave instability is found to be not possible when the effective on-site interaction between polarons is repulsive

Jahn-Teller polarons and their superconductivity in a molecular conductor

We present a theoretical study of a possibility of superconductivity in a three dimensional molecular conductor in which the interaction between electrons in doubly degenerate molecular orbitals and an {\em intra}molecular vibration mode is large enough to lead to the formation of $E\otimes \beta$ Jahn-Teller small polarons. We argue that the effective polaron-polaron interaction can be attractive for material parameters realizable in molecular conductors. This interaction is the source of superconductivity in our model. On analyzing superconducting instability in the weak and strong coupling regimes of this attractive interaction, we find that superconducting transition temperatures up to 100 K are achievable in molecular conductors within this mechanism. We also find, for two particles per molecular site, a novel Mott insulating state in which a polaron singlet occupies one of the doubly degenerate orbitals on each site. Relevance of this study in the search for new molecular superconductors is pointed out.Comment: Submitted to Phys. Rev.

Impact of the Covid 19 Pandemic on the Indian Economy: A Critical Assessment (NIAS/NSE/EEP/U/WP/18/2020)

This paper analyses the economic impact of Covid-19 in India. It documents the trajectory of infections and the lockdown and evaluates the extent of economic losses due to the lockdown. It also critically assesses the economic response of the Indian government to the pandemic and the lockdown

Specific heat of Bosons in a lattice

We present a theoretical study of specific heat of bosons ($C_v$) in a simple cubic lattice. We have studied the non-interacting bosons and the Tonks gas. For both cases, the $C_v$ above the bose condensation temperature shows considerable temperature dependence compared to that of free bosons. For Tonks gas, we find that the low-temperature specific heat increases as the system gets closer to the Mott transition