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Konstantin Glaum

Publications and source records attributed to Konstantin Glaum.

6 recordsLinked to original sources
arXiv2007

Condensation of Ideal Bose Gas Confined in a Box Within a Canonical Ensemble

We set up recursion relations for the partition function and the ground-state occupancy for a fixed number of non-interacting bosons confined in a square box potential and determine the temperature dependence of the specific heat and the particle number in the ground state. A proper semiclassical treatment is set up which yields the correct small-T-behavior in contrast to an earlier theory in Feynman's textbook on Statistical Mechanics, in which the special role of the ground state was ignored. The results are compared with an exact quantum mechanical treatment. Furthermore, we derive the finite-size effect of the system.

cond-mat.stat-mech↗
arXiv2007

Bose-Einstein Condensation Temperature of Dipolar Gas in Anisotropic Harmonic Trap

We consider a dilute gas of dipole moments in an arbitrary harmonic trap and treat both the short-range, isotropic delta-interaction and the long-range, anisotropic dipole-dipole interaction perturbatively. With this we calculate the leading shift of the critical temperature with respect to that of an ideal gas as a function of the relative orientation of the dipole moments with respect to the harmonic trap axes. In particular, we determine those magic angles, where the dipolar shift of the Bose-Einstein condensation temperature vanishes. Furthermore, we show for the parameters of the ongoing 52Cr-experiment in Stuttgart that this dipolar shift can be enhanced by increasing the number of particles, the geometrical mean trap frequency, and the anisotropy of the trap.

cond-mat.stat-mech↗
arXiv2007

Critical Temperature of Weakly Interacting Dipolar Condensates

We calculate perturbatively the effect of a dipolar interaction upon the Bose-Einstein condensation temperature. This dipolar shift depends on the angle between the symmetry axes of the trap and the aligned atomic dipole moments, and is extremal for parallel or orthogonal orientations, respectively. The difference of both critical temperatures exhibits most clearly the dipole-dipole interaction and can be enhanced by increasing both the number of atoms and the anisotropy of the trap. Applying our results to chromium atoms, which have a large magnetic dipole moment, shows that this dipolar shift of the critical temperature could be measured in the ongoing Stuttgart experiment.

cond-mat.stat-mech↗
arXiv2003

Recursive Graphical Solution of Closed Schwinger-Dyson Equations in phi^4-Theory -- Part1: Generation of Connected and One-Particle Irreducible Feynman Diagrams

Using functional derivatives with respect to the free correlation function we derive a closed set of Schwinger-Dyson equations in phi^4-theory. Its conversion to graphical recursion relations allows us to systematically generate all connected and one-particle irreducible Feynman diagrams for the two- and four-point function together with their weights.

hep-th↗
arXiv2002

Many-Body Vacuum Diagrams and Their Recursive Graphical Construction

The grand-canonical potential of many-body physics can be considered as a functional of the interaction-free correlation function. As such it obeys a nonlinear functional differential equation which can be turned into a recursion relation. This is solved graphically order by order in the two-particle interaction to find all connected vacuum diagrams with their proper weights. As a special case, the procedure is applied to generate the Hugenholtz diagrams for a weakly interacting Bose gas.

cond-mat↗