33 research outputs found
Bose-Einstein condensation of the magnetized ideal Bose gas
We study the charged non-relativistic Bose gas interacting with a constant
magnetic field but which is otherwise free. The notion of Bose-Einstein
condensation for the three dimensional case is clarified, and we show that
although there is no condensation in the sense of a phase transition, there is
still a maximum in the specific heat which can be used to define a critical
temperature. Although the absence of a phase transition persists for all values
of the magnetic field, we show how as the magnetic field is reduced the curves
for the specific heat approach the free field curve. For large values of the
magnetic field we show that the gas undergoes a "dimensional reduction" and
behaves effectively as a one-dimensional gas except at very high temperatures.
These general features persist for other spatial dimensions D and we show
results for D=5. Finally we examine the magnetization and the
Meissner-Ochsenfeld effect.Comment: 4 pages RevTex 2 column format with 4 eps figures, uses epsf.
Replaced version has missing acknowledgements and a discussion of two
references is corrected thanks to discussions with J. Daicic and N. Franke
Chiral symmetry in linear Sigma model in magnetic environment
We study the chiral symmetry structure in a linear sigma model with fermions
in the presence of an external, uniform magnetic field in the 'effective
potential' approach at the one loop level. We also study the chiral phase
transition as a function of density in the core of magnetized neutron stars.Comment: LaTex2e file with six postscript figures. journal ref: Physical
Review D 62 (2000) 02502
Thermal Versus Vacuum Magnetization in QED
The magnetized relativistic Fermi and Bose gases are studied at finite
temperature and density.In the case of the Fermi gas, the contribution to the
magnetization from the vacuum becomes dominant for high magnetic fields, when
the thermal contribution saturates.
In the case of the charged Bose gas, the (paramagnetic) vacuum--magnetization
becomes dominant when the gas changes from a diamagnetic to a paramagnetic
behaviour. We furthermore find that the scalar--QED effective coupling constant
for a weak non--zero external magnetic field is a decreasing function of the
temperature.Comment: 8 pages. G\"oteborg ITP 94-1
Chiral thermodynamics in a magnetic field
We study thermodynamic properties of the QCD vacuum in a magnetic field below
chiral phase transition. The hadronic phase free energy in a constant
homogeneous magnetic field is calculated in the framework of the chiral
perturbation theory at non-zero pionic mass. It is demonstrated that the order
parameter of the chiral phase transition remains constant provided temperature
and magnetic field strength are related through obtained equation (the
phenomenon of ''quark condensate freezing'').Comment: RevTeX4, 9 pages, no figure
Symmetry structure and phase transitions
We study chiral symmetry structure at finite density and temperature in the
presence of external magnetic field and gravity, a situation relevant in the
early Universe and in the core of compact stars.
We then investigate the dynamical evolution of phase transition in the
expanding early Universe and possible formation of quark nuggets and their
survival.Comment: Plenary talk given at the 4th. ICPAQGP held at Jaipur, India from Nov
26-30, 2001.laTex 2e file with 8 ps figures and 12 page
Undulating Charged Fluid Membranes and their Bending Constants
We consider harmonically undulating ionic surfactant membranes, calculating a general expression for the bending modulus valid for all salt and surfactant concentrations, and surface charge densities. This is achieved through a perturbative expansion of the meanfield electrostatic potential and free energy about a planar reference state, consisting of two parallel planar membranes with intervening salt solution. For a given choice of undulation mode, the result for the bending modulus is seen to be generally the same as that obtained from considerations of membranes deformed into a cylindrical geometry. Thus, we show that the bending modulus is independent of global aggregate geometry, at a general system composition. Specializing to the limit of excess added salt (equivalent to a single undulating membrane in contact with bulk electrolyte), we are able to extend the free energy calculation to fourth order in undulation amplitude, and derive the bending constants of the curvature expansion to this order. These have been suggested previously to be of importance in explaining the stability of bicontinuous crystalline and disordered phases, and the formation of passages in lamellar phases. We also discuss the breakdown of the curvature description at shorter wavelengths
Stress development during drying of calcium carbonate suspensions containing carboxymethylcellulose and latex particles
Stress development during drying of coatings produced from aqueous dispersions of calcium carbonate particles in the presence and absence of organic binders was studied using a controlled-environment stress apparatus that simultaneously monitored drying stress, weight loss, and relative humidity. Specifically, the influence of two organic binders on drying stress evolution was investigated: (1) carboxymethylcellulose, a water-soluble viscosifying aid, and (2) a styrene-butadiene latex emulsion of varying glass transition temperature. The stress histories exhibited three distinct regions. First, a period of stress rise was observed, which reflected the capillary tension exerted by the liquid on the particle network. Second, a maximum stress was observed. Third, it was followed by a period of either stress decay or rise depending on the organic species present. Significant differences in stress histories were observed between coatings containing soluble and nonsoluble binders. Maximum drying stresses (Ïmax) of 0.2-0.5 MPa were observed for coatings produced from pure calcium carbonate or calcium carbonate-latex suspensions, whereas coatings with carboxymethylcellulose exhibited substantially higher Ïmax values of 1-2 MPa. Upon drying, these coatings were quite hygroscopic, such that cyclic variations in relative humidity induced large cyclic changes in residual stress