scholarly journals PHASE TRANSITION OF N-COMPONENT SUPERCONDUCTORS

1996 ◽  
Vol 11 (23) ◽  
pp. 4273-4306 ◽  
Author(s):  
B. BERGERHOFF ◽  
D.F. LITIM ◽  
S. LOLA ◽  
C. WETTERICH
Keyword(s):  
Phase Transition ◽  
Three Dimensional ◽  
Gauge Coupling ◽  
Scalar Fields ◽  
Flow Equation ◽  
Second Order ◽  
Complex Scalar ◽  
Gauge Invariant ◽  
Second Order Transition ◽  
Average Action

We investigate the phase transition in the three-dimensional Abelian Higgs model for N complex scalar fields, using the gauge-invariant average action Γk. The dependence of Γk. on the effective infrared cutoff k is described by a nonperturbative flow equation. The transition turns out to be first or second order, depending on the ratio between the scalar and gauge coupling. We look at the fixed points of the theory for various N and compute the critical exponents of the model. Our results suggest the existence of a parameter range with a second order transition for all N, including the case of the superconductor phase transition for N=1.

scholarly journals BARYOGENESIS VIA DENSITY FLUCTUATIONS WITH A SECOND ORDER ELECTROWEAK PHASE TRANSITION

2003 ◽  
Vol 18 (26) ◽  
pp. 4851-4868 ◽  
Author(s):  
BISWANATH LAYEK ◽  
SOMA SANYAL ◽  
AJIT M. SRIVASTAVA
Keyword(s):  
Phase Transition ◽  
Baryon Asymmetry ◽  
Density Fluctuations ◽  
Second Order ◽  
Baryon Production ◽  
Electroweak Phase Transition ◽  
Expansion Of The Universe ◽  
Second Order Transition ◽  
Background Temperature ◽  
The Universe

We consider the presence of cosmic string induced density fluctuations in the universe at temperatures below the electroweak phase transition temperature. Resulting temperature fluctuations can restore the electroweak symmetry locally, depending on the amplitude of fluctuations and the background temperature. The symmetry will be spontaneously broken again in a given fluctuation region as the temperature drops there (for fluctuations with length scales smaller than the horizon), resulting in the production of baryon asymmetry. The time scale of the transition will be governed by the wavelength of fluctuation and, hence, can be much smaller than the Hubble time. This leads to strong enhancement in the production of baryon asymmetry for a second order electroweak phase transition as compared to the case when transition happens due to the cooling of the universe via expansion. For a two-Higgs extension of the Standard Model (with appropriate CP violation), we show that one can get the required baryon to entropy ratio if fluctuations propagate without getting significantly damped. If fluctuations are damped rapidly, then a volume factor suppresses the baryon production. Still, the short scale of the fluctuation leads to enhancement of the baryon to entropy ratio by at least 3–4 orders of magnitude compared to the conventional case of second order transition where the cooling happens due to expansion of the universe.

scholarly journals SOLVING NONPERTURBATIVE FLOW EQUATIONS

1995 ◽  
Vol 10 (31) ◽  
pp. 2367-2379 ◽  
Author(s):  
J. ADAMS ◽  
N. TETRADIS ◽  
J. BERGES ◽  
F. FREIRE ◽  
C. WETTERICH ◽  
...  
Keyword(s):  
Field Theory ◽  
Scalar Field ◽  
Critical Behavior ◽  
Good Accuracy ◽  
Three Dimensional ◽  
Scale Dependence ◽  
Flow Equation ◽  
Flow Equations ◽  
Approximate Form ◽  
Average Action

Nonperturbative exact flow equations describe the scale dependence of the effective average action. We present a numerical solution for an approximate form of the flow equation for the potential in a three-dimensional N-component scalar field theory. The critical behavior, with associated critical exponents, can be inferred with good accuracy.

The spontaneous polarization as evidence for lithium disordering in LiNbO3

1990 ◽  
Vol 5 (9) ◽  
pp. 1933-1939 ◽  
Author(s):  
Dunbar P. Birnie
Keyword(s):  
Phase Transition ◽  
Spontaneous Polarization ◽  
Paraelectric Phase ◽  
Second Order ◽  
Polarization Data ◽  
Paraelectric Phase Transition ◽  
Microscopic Mechanism ◽  
Second Order Transition ◽  
Displacement Model ◽  
Insight Into

The ferroelectric to paraelectric phase transition in lithium niobate is examined. The present study focuses on the microscopic mechanism for this phase transition. Literature reports that give insight into this mechanism are reviewed. Two alternate mechanisms for this second order transition have been discussed previously. The phase transition has been proposed to occur by either (a) cooperative displacement of Li ions or (b) statistical disordering of Li between two octahedral sites in the structure. The present study develops a general Landau expression for the second order phase transition. The spontaneous polarization of the lattice is used as an indicator of the extent of transformation. Then both displacement and disordering models are explored. These are compared with the observed spontaneous polarization data. It is concluded that the spontaneous polarization data are indicative of a Li disordering model, rather than a Li displacement model.

scholarly journals Dreibein as Prepotential for Three-Dimensional Yang-Mills Theory

2017 ◽  
Vol 2017 ◽  
pp. 1-7
Author(s):  
Indrajit Mitra ◽  
H. S. Sharatchandra
Keyword(s):  
Boundary Condition ◽  
Gauge Transformation ◽  
Three Dimensional ◽  
Scalar Fields ◽  
Gauge Potential ◽  
Conformally Flat ◽  
Gauge Invariant ◽  
Yang Mills ◽  
Conformally Flat Metrics

We advocate and develop the use of the dreibein (and the metric) as prepotential for three-dimensional SO(3) Yang-Mills theory. Since the dreibein transforms homogeneously under gauge transformation, the metric is gauge invariant. For a generic gauge potential, there is a unique dreibein on fixing the boundary condition. Topologically nontrivial monopole configurations are given by conformally flat metrics, with scalar fields capturing the monopole centres. Our approach also provides an ansatz for the gauge potential covering the topological aspects.

ON SPONTANEOUS PARITY BREAKING IN THREE-DIMENSIONAL GAUGE-HIGGS SYSTEMS

1991 ◽  
Vol 06 (33) ◽  
pp. 3099-3112 ◽  
Author(s):  
J. AMBJØRN ◽  
K. FARAKOS ◽  
M. E. SHAPOSHNIKOV
Keyword(s):  
Phase Transition ◽  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Ground State ◽  
Three Dimensional ◽  
Spontaneous Breaking ◽  
Gauge Invariant ◽  
Local Gauge ◽  
Parity Breaking

We address the question of spontaneous breaking of parity in three-dimensional Euclidean SU(2) gauge-Higgs theory by Monte–Carlo simulations. We observe no sign of spontaneous parity breaking in the behavior of local gauge invariant operators. However, the presence of parity-odd terms in the action can induce a phase transition to a parity-odd ground state.

APPLICATION OF THE RENORMALIZATION GROUP TO A SECOND-ORDER QCD PHASE TRANSITION

1992 ◽  
Vol 07 (16) ◽  
pp. 3911-3925 ◽  
Author(s):  
FRANK WILCZEK
Keyword(s):  
Phase Transition ◽  
Renormalization Group ◽  
Strange Quark ◽  
Tricritical Point ◽  
Universality Class ◽  
Second Order ◽  
Chiral Phase ◽  
Quark Masses ◽  
Potential Applications ◽  
Second Order Transition

An earlier suggestion that the chiral phase transition in QCD for two flavors of massless quarks might be a second-order transition has gained credibility as a result of recent numerical simulations. One can test this hypothesis, and draw very specific quantitative consequences from it, using universality and renormalization group ideas. This hypothetical second order phase transition is in the universality class of a four component isotropic Heisenberg antiferromagnet—a model which has been investigated intensely by condensed matter physicists. Existing calculations can be adapted to yield predictions for critical exponents governing the QCD transition. The perturbation due to small equal quark masses maps onto an external staggered magnetic field; that due to unequal quark masses is effective only in second order and generates a quadratic anisotropy. Several other potential applications of the renormalization group to related questions are suggested, including a model of the tricritical point which arises with finite strange quark mass, and a model for the dynamic critical behavior.

Three-Dimensional Numerical Calculations of a Jet in an External Cross Flow: Application to Pollutant Dispersion

2003 ◽  
Vol 125 (3) ◽  
pp. 510-522 ◽  
Author(s):  
Nejla Mahjoub Said ◽  
Hatem Mhiri ◽  
Salem El Golli ◽  
Georges Le Palec ◽  
Philippe Bournot
Keyword(s):  
Three Dimensional ◽  
Cross Flow ◽  
Pollutant Dispersion ◽  
Scalar Fields ◽  
Second Order ◽  
Turbulent Jet ◽  
Dimensional Structure ◽  
Order Model ◽  
Air Stream ◽  
Helium Jet

The paper presents a three-dimensional numerical simulation of a circular turbulent jet issuing transversely into a uniform air stream. In the first part an air-helium jet is considered and the three-dimensional structure of the flow field is discussed. Then, a comparison between the numerical results of four turbulence closure models (three first-order models and a second-order one) are presented and compared with the experimental data given by Crabb et al. [7] and Andreopoulos et al. [9]. Although the different models render identical results in the upstream and far downstream regions of the jet, only the second order model is shown to give good results in the exit region and in the trailing zone of the jet. Based on this last model, the dynamic and scalar fields of a fume turbulent jet issuing transversely with velocity v0 into a uniform air flow with velocity u are then examined as functions of the ratio R=v0/u∞ in order to simulate pollutant dispersion from industrial chimneys.

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