Talk given at Strong and Electroweak matter 2008, Amsterdam August 25-29 2008. Four pages and two figures. 2nd version: typos fixed and updated list of refs
本文采用O（4）对称线性西格玛模型作为双味QCD的有效场论，研究了有限同位旋化学势$μ_I$下QCD中带电π介子的玻色凝聚问题.使用2 PI $1/N$ -展开，我们确定准粒子的质量，以及π介子和手征凝聚体的函数的温度和同位旋化学势的手征极限和在物理点。在T=0时，当化学势大于$m_π$时，发生玻色凝聚。在手征极限下，对于$μ_I$的任何有限值，手征凝聚为零。
英文摘要：
We consider the problem of Bose condensation of charged pions in QCD at finite isospin chemical potential $μ_I$ using the O(4)-symmetric linear sigma model as an effective field theory for two-flavor QCD. Using the 2PI $1/N$-expansion, we determine the quasiparticle masses as well as the pion and chiral condensates as a function of the temperature and isospin chemical potential in the chiral limit and at the physical point. At T=0, Bose condensation takes place for chemical potentials larger than $m_π$. In the chiral limit, the chiral condensate vanishes for any finite value of $μ_I$.
A system of bosons studied within the mean field framework has two fascinating phenomena: a liquid-gas first order phase transition and Bose-Einstein condensation. Interplay between these two phenomena is being investigated. Depending on the mean-field potential parameters one can observe two types of critical points, called "Boltzmann" and "Bose", that belong to different universality classes with distinct sets of critical exponents. As examples of Bose and Boltzmann CPs pion and $α$ matter are considered, respectively. In general, the phase diagram can have one of the CPs or both of them.
We study the Bose condensation of scalar dark matter in the presence of both gravitational and self-interactions. Axions and other scalar dark matter in gravitationally bound miniclusters or dark matter halos are expected to condense into Bose-Einstein condensates called Bose stars. This process has been shown to occur through attractive self-interactions of the axion-like particles or through the field's self gravitation. We show that in the high-occupancy regime of scalar dark matter, the Boltzmann collision integral does not describe either gravitaitonal or self-interactions, and derive kin…
The Bose-Einstein condensation and the liquid-gas first order phase transition are studied in the interacting pion matter. Two phenomenological models are used: the mean-field model and the hybrid model. Free model parameters are fixed by fitting the lattice QCD data on the pion Bose condensate density at zero temperature. In spite of some minor differences the two model demonstrate an identical qualitative and very close quantitative behavior for the thermodynamic functions and electric charge fluctuations. A peculiar property of the considered models is an intersection of the Bose-Einstein c…
In this paper, we study the Bose-Einstein condensation of a scalar field with an attractive self-interaction, with or without gravitational interactions. We confirm through full dynamical simulation that the condensation timescale due to self-interaction is inversely proportional to the square of the number density $n$ and the self-coupling constant $g$ : $τ\propto n^{-2} g^{-2}$. We also investigate the condensation timescale when self-interaction and gravity are both important by solving the Gross-Pitaevskii-Poisson equations, and find that the condensation time scales according to an additi…
We study Bose-Einstein condensation and formation of Bose stars in the virialized dark matter halos/miniclusters by universal gravitational interactions. We prove that this phenomenon does occur and it is described by kinetic equation. We give expression for the condensation time. Our results suggest that Bose stars may form kinetically in the mainstream dark matter models such as invisible QCD axions and Fuzzy Dark Matter.
We review the properties of chaoticity and coherence in Bose-Einstein condensation and correlations, for a dense boson system in its mean-field represented approximately by a harmonic oscillator potential. The order parameter and the nature of the phase transition from the chaotic to the condensate states are studied for different fixed numbers of bosons. The two-particle correlation function in momentum space is calculated to investigate how the Bose-Einstein correlation depends on the degree of condensation and other momentum variables. We generalize the Bose-Einstein correlation analysis to…
