• Exponentiation problem in the construction of an effective low-momentum Hamiltonian for bosons

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      https://www.ias.ac.in/article/fulltext/pram/025/06/0649-0661

    • Keywords

       

      Exponentiation; low-momentum Hamiltonian; bosons; connected graph; disconnected graph; partial trace; renormalization group; time-ordered product; double-commutator

    • Abstract

       

      The problem of exponentiation of connected-graph contributionsC, when one carries out only a partial trace of the density matrix of an assembly of bosons in order to construct an effective, low-momentum Hamiltonian, is examined. It is found that besides accounting for the exponentiation of connected graphs, disconnected graphs contribute certain termsD to connected-graph contributions. TheD-terms diminish as the number of iterations increases in the Singh’s renormalization-group theory for the present system. Therefore, these terms play no role in determining critical behaviour of the system.

    • Author Affiliations

       

      Partha Goswami1

      1. Department of Physics and Astrophysics, University of Delhi, Delhi - 110 007, India
    • Dates

       
  • Pramana – Journal of Physics | News

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      Posted on July 25, 2019

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