• K K Singh

      Articles written in Pramana – Journal of Physics

    • Statistical mechanics of bosons with attractive interaction

      K K Singh Jai Prakash

      More Details Abstract Fulltext PDF

      In order to obtain meaningful results for a system of bosons interacting via a potential containing a long-ranged attraction, the coupling of low momentum particles with high momentum particles has to be taken into account. The method of thermal Green’s functions applied to this problem leads to involved graphical calculations even for temperatures close to the absolute zero. It is shown that the problem can be tackled much more simply and profitably by obtaining an effective hamiltonian for low momentum particles in a manner similar to that adopted in the recent renormalisation group approach to critical phenomena. The occurrence of anomalous pairings is avoided by performing suitable Bogolubov transformations. The procedure gives the quasiparticle spectrum besides yielding an explicit expression for the free energy in the low temperature limit. The results agree with those derived by Green’s function methods using partial summations.

    • Renormalisation group approach to the ideal Bose gas ind dimensions

      K K Singh

      More Details Abstract Fulltext PDF

      Critical behaviour of ad-dimensional ideal Bose gas is investigated from the point of view of the renormalisation-group approach. Rescaling of quantum-field amplitudes is avoided by introducing a scaling variable inversely proportional to the thermal momentum of the particles. The scaling properties of various thermodynamic quantities are seen to emerge as a consequence of the irrelevant nature of this variable. Critical behaviour is discussed at fixed particle density as well as at fixed pressure. Connection between susceptibility and correlation function of the order-parameter for a quantum system is elucidated.

  • Pramana – Journal of Physics | News

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

© 2021-2022 Indian Academy of Sciences, Bengaluru.