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.

ν-DIMENSIONAL IDEAL QUANTUM q-GAS: BOSE-EINSTEIN CONDENSATION AND λ-POINT TRANSITION

1994 ◽  
Vol 08 (23) ◽  
pp. 3281-3298 ◽  
Author(s):  
M. R-MONTEIRO ◽  
ITZHAK RODITI ◽  
LIGIA M.C.S. RODRIGUES
Keyword(s):  
Critical Temperature ◽  
Chemical Potential ◽  
Ideal Gas ◽  
Einstein Condensation ◽  
Bose Einstein Condensation ◽  
Spatial Dimensions ◽  
Quantum Symmetries ◽  
Ideal Quantum ◽  
Bose Einstein ◽  
Λ Point

We consider an ideal quantum q-gas in ν spatial dimensions and energy spectrum ωiα pα Departing from the Hamiltonian H=ω[N], we study the effect of the deformation on thermodynamic functions and equation of state of that system. The virial expansion is obtained for the high temperature (or low density) regime. The critical temperature is higher than in non-deformed ideal gases. We show that Bose-Einstein condensation always exists (unless when ν/α=1) for finite q but not for q=∞. Employing numerical calculations and selecting for v/α the values 3/2, 2 and 3, we show the critical temperature as a function of q, the specific heat CV and the chemical potential µ as functions of [Formula: see text] for q=1.05 and q=4.5. CV exhibits a λ-point discontinuity in all cases, instead of the cusp singularity found in the usual ideal gas. Our results indicate that physical systems which have quantum symmetries can exhibit Bose-Einstein condensation phenomenon, the critical temperature being favored by the deformation parameter.

scholarly journals Evidence for spin current driven Bose-Einstein condensation of magnons

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
B. Divinskiy ◽  
H. Merbouche ◽  
V. E. Demidov ◽  
K. O. Nikolaev ◽  
L. Soumah ◽  
...  
Keyword(s):  
Room Temperature ◽  
Chemical Potential ◽  
Spin Current ◽  
Einstein Condensation ◽  
Electronic Control ◽  
Spintronic Devices ◽  
Bose Einstein Condensation ◽  
Magnetic Insulators ◽  
Spatially Extended ◽  
Bose Einstein

AbstractThe quanta of magnetic excitations – magnons – are known for their unique ability to undergo Bose-Einstein condensation at room temperature. This fascinating phenomenon reveals itself as a spontaneous formation of a coherent state under the influence of incoherent stimuli. Spin currents have been predicted to offer electronic control of Bose-Einstein condensates, but this phenomenon has not been experimentally evidenced up to now. Here we show that current-driven Bose-Einstein condensation can be achieved in nanometer-thick films of magnetic insulators with tailored nonlinearities and minimized magnon interactions. We demonstrate that, above a certain threshold, magnons injected by the spin current overpopulate the lowest-energy level forming a highly coherent spatially extended state. We quantify the chemical potential of the driven magnon gas and show that, at the critical current, it reaches the energy of the lowest magnon level. Our results pave the way for implementation of integrated microscopic quantum magnonic and spintronic devices.

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 Bose-Einstein Condensation of Confined Atomic Gases at Ultra Low Temperatures

2017 ◽  
Vol 9 (5) ◽  
pp. 96
Author(s):  
M. Serhan
Keyword(s):  
Low Temperatures ◽  
Chemical Potential ◽  
Scattering Length ◽  
Einstein Condensation ◽  
Pitaevskii Equation ◽  
Atomic Gases ◽  
Bose Einstein Condensation ◽  
Gaussian Type ◽  
Negative Scattering Length ◽  
Bose Einstein

In this work I solve the Gross-Pitaevskii equation describing an atomic gas confined in an isotropic harmonic trap by introducing a variational wavefunction of Gaussian type. The chemical potential of the system is calculated and the solutions are discussed in the weakly and strongly interacting regimes. For the attractive system with negative scattering length the maximum number of atoms that can be put in the condensate without collapse begins is calculated.

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.

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