scholarly journals CHAOTIC PARAMETER λ IN HANBURY-BROWN–TWISS INTERFEROMETRY IN AN ANISOTROPIC BOSON GAS MODEL

2013 ◽  
Vol 22 (11) ◽  
pp. 1350083 ◽  
Author(s):  
JIE LIU ◽  
PENG RU ◽  
WEI-NING ZHANG ◽  
CHEUK-YIN WONG
Keyword(s):  
Correlation Functions ◽  
Particle Number ◽  
Hadron Collider ◽  
Heavy Ion ◽  
Einstein Condensation ◽  
Bose Einstein Condensation ◽  
Particle Pair ◽  
Average Momentum ◽  
Chaotic Parameter ◽  
Bose Einstein

Using one- and two-body density matrices, we calculate the spatial and momentum distributions, two-particle Hanbury-Brown–Twiss (HBT) correlation functions, and the chaotic parameter λ in HBT interferometry for the systems of boson gas within the harmonic oscillator potentials with anisotropic frequencies in transverse and longitudinal directions. The HBT chaotic parameter, which can be obtained by measuring the correlation functions at zero relative momentum of the particle pair, is related to the degree of Bose–Einstein condensation and thus the system environment. We investigate the effects of system temperature, particle number and the average momentum of the particle pair on the chaotic parameter. The value of λ decreases with the condensed fraction, f0. It is one for f0 = 0 and zero for f0 = 1. For a certain f0 between 0 and 1, we find that λ increases with the average momentum of the particle pair and decreases with the particle number of system. The results of λ are sensitive to the ratio, ν = ωz/ωρ, of the frequencies in longitudinal and transverse directions. They are smaller for larger ν when ωρ is fixed. In the heavy-ion collisions at the Large Hadron Collider (LHC) energy the large identical pion multiplicity may possibly lead to a considerable Bose–Einstein condensation. Its effect on the chaotic parameter in two-pion interferometry is worth considering in earnest.

scholarly journals Spontaneously Broken Gauge Symmetry in a Bose Gas with Constant Particle Number

2017 ◽  
Vol 16 (01) ◽  
pp. 1750009
Author(s):  
A. Schelle
Keyword(s):  
Gauge Symmetry ◽  
Particle Number ◽  
Present Model ◽  
Phase Distribution ◽  
Equations Of Motion ◽  
Einstein Condensation ◽  
Bose Einstein Condensation ◽  
Gauge Symmetries ◽  
Non Local ◽  
Bose Einstein

The interplay between spontaneously broken gauge symmetries and Bose–Einstein condensation has long been controversially discussed in science, since the equations of motion are invariant under phase transformations. Within the present model, it is illustrated that spontaneous symmetry breaking appears as a non-local process in position space, but within disjoint subspaces of the underlying Hilbert space. Numerical simulations show that it is the symmetry of the relative phase distribution between condensate and non-condensate quantum fields which is spontaneously broken when passing the critical temperature for Bose–Einstein condensation. Since the total number of gas particles remains constant over time, the global U(1)-gauge symmetry of the system is preserved.

scholarly journals Particle number fluctuations in a non-ideal pion gas

2018 ◽  
Vol 182 ◽  
pp. 02066
Author(s):  
Evgeni E. Kolomeitsev ◽  
Maxim E. Borisov ◽  
Dmitry N. Voskresensky
Keyword(s):  
Critical Point ◽  
Particle Number ◽  
Chemical Potential ◽  
Pion Mass ◽  
Thermodynamic Characteristics ◽  
Ideal Gas ◽  
Fixed Number ◽  
Einstein Condensation ◽  
Bose Einstein Condensation ◽  
Bose Einstein

We consider a non-ideal hot pion gas with the dynamically fixed number of particles in the model with the λφ4 interaction. The effective Lagrangian for the description of such a system is obtained by dropping the terms responsible for the change of the total particle number. Within the self-consistent Hartree approximation, we compute the effective pion mass, thermodynamic characteristics of the system and identify a critical point of the induced Bose-Einstein condensation when the pion chemical potential reaches the value of the effective pion mass. The normalized variance, skewness, and kurtosis of the particle number distributions are calculated. We demonstrate that all these characteristics remain finite at the critical point of the Bose-Einstein condensation. This is due to the non-perturbative account of the interaction and is in contrast to the ideal-gas case.

Effect of pion versus kaon interferometry on the chaotic parameter

2015 ◽  
Vol 30 (18) ◽  
pp. 1550086
Author(s):  
Jie Liu ◽  
Li-Dong Zhao ◽  
Xiao-Zhao Xu ◽  
Hui-Zeng Yin
Keyword(s):  
Harmonic Oscillator ◽  
Einstein Condensation ◽  
Oscillator Potential ◽  
Harmonic Oscillator Potential ◽  
Bose Einstein Condensation ◽  
Kaon Interferometry ◽  
Chaotic Parameter ◽  
Bose Einstein

In this paper, the advantages of pion versus kaon interferometry as a measure to probe the degree of source coherence are studied by a expanding boson gas model with a harmonic oscillator potential. We investigate the conditions about occurrence of Bose–Einstein condensation and analyze its impacts on the chaotic parameter λ. The results indicate that this finite condensation for pion system decreases the value of λ, but influence slightly for kaon system.

THE EFFECTS OF A FINITE NUMBER OF PARTICLES ON TWO TRAPPED QUANTUM GASES

2011 ◽  
Vol 25 (32) ◽  
pp. 4435-4442
Author(s):  
LIWEI CHEN ◽  
GUOZHEN SU ◽  
JINCAN CHEN
Keyword(s):  
Finite Number ◽  
Particle Number ◽  
Bose Gas ◽  
Quantum Gases ◽  
Einstein Condensation ◽  
Thermodynamic Quantities ◽  
Bose Einstein Condensation ◽  
Bose Einstein ◽  
Finite Particle ◽  
Number Of Particles

The effects of a finite number of particles on the thermodynamic properties of ideal Bose and Fermi gases trapped in any-dimensional harmonic potential are investigated. The orders of relative corrections to the thermodynamic quantities due to the finite number of particles are estimated in different situations. The results obtained for the two trapped quantum gases are compared, and consequently, it is shown that the finite-particle-number effects for the condensed Bose gas (a Bose gas with Bose–Einstein Condensation (BEC) occurring in the system) are much more significant than those for the Fermi gas and normal Bose gas (a Bose gas without BEC).

Systems with Condensates and Pairing

2018 ◽  
Author(s):  
Klaus Morawetz
Keyword(s):  
Critical Parameters ◽  
Einstein Condensation ◽  
Cooper Pairs ◽  
Pair Breaking ◽  
Systematic Theory ◽  
Bose Einstein Condensation ◽  
T Matrix ◽  
The Stability ◽  
Bose Einstein

The Bose–Einstein condensation and appearance of superfluidity and superconductivity are introduced from basic phenomena. A systematic theory based on the asymmetric expansion of chapter 11 is shown to correct the T-matrix from unphysical multiple-scattering events. The resulting generalised Soven scheme provides the Beliaev equations for Boson’s and the Nambu–Gorkov equations for fermions without the usage of anomalous and non-conserving propagators. This systematic theory allows calculating the fluctuations above and below the critical parameters. Gap equations and Bogoliubov–DeGennes equations are derived from this theory. Interacting Bose systems with finite temperatures are discussed with successively better approximations ranging from Bogoliubov and Popov up to corrected T-matrices. For superconductivity, the asymmetric theory leading to the corrected T-matrix allows for establishing the stability of the condensate and decides correctly about the pair-breaking mechanisms in contrast to conventional approaches. The relation between the correlated density from nonlocal kinetic theory and the density of Cooper pairs is shown.

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