2007/05/31 by C. Wetterich · 6 citations
Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #Physics of Superconductivity and Magnetism #Quantum Chromodynamics and Particle Interactions #astro-ph #cond-mat.str-el #cond-mat.supr-con #hep-th
paper · pdf · doi:10.1103/physrevb.77.064504
31 pages, new references
openalex publication_date 2008/02/11 · arxiv created 2008/02/29 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Functional renormalization yields a simple unified description of bosons at zero temperature, in arbitrary space dimension d and for M complex fields. We concentrate on nonrelativistic bosons and an action with a linear time derivative. The ordered phase can be associated with a nonzero density of (quasi)particles n. The behavior of observables and correlation functions in the ordered phase depends crucially on the momentum kph, which is characteristic for a given experiment. For the dilute regime kph\ensuremath\gtrsimn1∕d, the quantum phase transition is simple, with the same ``mean field'' critical exponents for all d and M. On the other hand, the dense regime kph⪡n1∕d reveals a rather rich spectrum of features, depending on d and M. In this regime, one observes for d\ensuremath\leqslant3 a crossover to a relativistic action with second time derivatives. This admits order for d>1, whereas d=1 shows a behavior similar to the low temperature phase of the classical two-dimensional O(2M) models.