1,199 research outputs found
Dilute Bose gas: short-range particle correlations and ultraviolet divergence
The modified Bogoliubov model where the primordial interaction is replaced by
the t matrix is reinvestigated. It is shown to provide a negative value of the
kinetic energy for a strongly interacting dilute Bose gas, contrary to the
original Bogoliubov model. To clear up the origin of this failure, the correct
values of the kinetic and interaction energies of a dilute Bose gas are
calculated. It is demonstrated that both the problem of the negative kinetic
energy and the ultraviolet divergence, dating back to the well-known paper of
Lee, Yang and Huang, is connected with an inadequate picture of the short-range
boson correlations. These correlations are reconsidered within the
thermodynamically consistent model proposed earlier by the present authors.
Found results are in absolute agreement with the data of the Monte-Carlo
calculations for the hard-sphere Bose gas.Comment: 11 pages, REVTeX, 2 figures inserte
Dilute Bose gas in two dimensions: Density expansions and the Gross-Pitaevskii equation
A dilute two-dimensional (2D) Bose gas at zero temperature is studied by the
method developed earlier by the authors. Low density expansions are derived for
the chemical potential, ground state energy, kinetic and interaction energies.
The expansion parameter is found to be a dimensionless in-medium scattering
amplitude u obeying the equation 1/u+\ln u=-\ln(na^2\pi)-2\gamma, where na^2
and \gamma are the gas parameter and the Euler constant, respectively. It is
shown that the ground state energy is mostly kinetic in the low density limit;
this result does not depend on a specific form of the pairwise interaction
potential, contrary to 3D case. A new form of 2D Gross-Pitaevskii equation is
proposed within our scheme.Comment: 4 pages, REVTeX, no figure
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