scholarly journals RELAXING NEAR THE CRITICAL POINT

2001 ◽  
Vol 16 (supp01c) ◽  
pp. 1274-1276
Author(s):  
M. SIMIONATO
Keyword(s):  
Critical Point ◽  
Heavy Ions ◽  
Distribution Functions ◽  
Critical Systems ◽  
Chiral Phase ◽  
Long Wavelength ◽  
Equilibrium Dynamics ◽  
Slowing Down ◽  
Large N ◽  
Early Universe Cosmology

I present an analysis of the relaxation rate for long-wavelength fluctuations of the order parameter in an O(N) scalar theory near the critical point. Our motivation is to model the non-equilibrium dynamics of critical fluctuations near the chiral phase transition in QCD. In the next-to-leading order in the large N expansion we find a critical slowing down regime, i.e. an increasing of the relaxation time of long wavelengths fluctuations. This result suggests, for near critical systems, relevant deviations from thermal equilibrium for the distribution functions of low-energy particles and could have important phenomenological consequences in Heavy Ions Collision and in the Early Universe Cosmology.

scholarly journals Persistent dynamic correlations in self-organized critical systems away from their critical point

2007 ◽  
Vol 373 ◽  
pp. 215-230 ◽  
Author(s):  
Ryan Woodard ◽  
David E. Newman ◽  
Raúl Sánchez ◽  
Benjamin A. Carreras
Keyword(s):  
Critical Point ◽  
Critical Systems ◽  
Dynamic Correlations ◽  
Self Organized

Transient fields acting on heavy ions during slowing-down in magnetized materials

1971 ◽  
Vol 166 (3) ◽  
pp. 413-435 ◽  
Author(s):  
Jens Lindhard ◽  
Aage Winther
Keyword(s):  
Heavy Ions ◽  
Slowing Down

Supercritical Adsorption

2005 ◽  
Author(s):  
Eldred H. Chimowitz
Keyword(s):  
Stationary Phase ◽  
Critical Point ◽  
Dynamic Models ◽  
Molecular Diffusion ◽  
Plug Flow ◽  
Fluid Phase ◽  
Commercial Application ◽  
Critical Systems ◽  
Mobile Phases ◽  
Column Dynamics

In this chapter, we discuss adsorption phenomena in supercritical systems, a situation that occurs in many application areas in chemical-process and materials engineering. An example of a commercial application in this area, which has achieved wide acceptance as a tool in analytical chemistry, is supercritical fluid chromatography (SFC). Not only is SFC a powerful technique for chemical analysis, but it also is a useful method for measuring transportive and thermodynamic properties in the near-critical systems. In the next section, we analyze adsorption-column dynamics using simple dynamic models, and describe how data from a chromatographic column can be used to estimate various thermodynamic and transport properties.We then proceed to discuss the effects of proximity to the critical point on adsorption behavior in these systems. The closer the system is to its critical point, the more interesting is its behavior. For very dilute solute systems, like those considered here, the energy balance is often ignored to a first approximation; this leads to a simple set of mass-balance equations defining transport for each species. These equations can be developed to various levels of complexity, depending upon the treatment of the adsorbent (stationary phase). The conceptual view of these phases can span a wide range of possibilities ranging from completely nonporous solids (fused structures) to porous materials with complicated ill-defined pore structures. Given these considerations, it is customary to make the following assumptions in the development of a simple model of adsorber-bed dynamics: . . .1. The stationary and mobile phases are continuous in the direction of the flow, with the fluid phase possessing a flat velocity profile (“plug” flow).. . . . . . 2. The porosity of the stationary phase is considered constant irrespective of pressure and temperature conditions (i.e., it is incompressible). . . . . . .3. The column is considered to be radially homogeneous, leading to a set of equations with one spatially independent variable, representing distance along the column axis. . . . . . . 4. The dispersion term in the model equation represents the combined effects of molecular diffusion and dispersion due to convective stirring in the bed. These effects are combined into an effective phenomenological dispersion coefficient, considered to be constant throughout the column. . . .

CHIRALLY EXTENDED QUANTUM CHROMODYNAMICS

1995 ◽  
Vol 06 (05) ◽  
pp. 725-742 ◽  
Author(s):  
RICHARD C. BROWER ◽  
YUE SHEN ◽  
CHUNG-I TAN
Keyword(s):  
Quantum Chromodynamics ◽  
Quark Mass ◽  
Continuum Limit ◽  
Chiral Limit ◽  
Scalar Fields ◽  
Weak Coupling Limit ◽  
Slowing Down ◽  
Large N ◽  
Chiral Invariance ◽  
The Continuum

We propose an extended Quantum Chromodynamics (XQCD) Lagrangian in which the fermions are coupled to elementary scalar fields through a Yukawa coupling which preserves chiral invariance. Our principle motivation is to find a new lattice formulation for QCD which avoids the source of critical slowing down usually encountered as the bare quark mass is tuned to the chiral limit. The phase diagram and the weak coupling limit for XQCD are studied. They suggest a conjecture that the continuum limit of XQCD is the same as the continuum limit of conventional lattice formulation of QCD. As examples of such universality, we present the large N solutions of two prototype models for XQCD, in which the mass of the spurious pion and sigma resonance go to infinity with the cut-off. Even if the universality conjecture turns out to be false, we believe that XQCD will still be useful as a low energy effective action for QCD phenomenology on the lattice. Numerical simulations are recommended to further investigate the possible benefits of XQCD in extracting QCD predictions.

scholarly journals Understanding the out-of-equilibrium dynamics near a critical point in the QCD phase diagram

2020 ◽  
Vol 102 (9) ◽  
Author(s):  
Krishna Rajagopal ◽  
Gregory W. Ridgway ◽  
Ryan Weller ◽  
Yi Yin
Keyword(s):  
Phase Diagram ◽  
Critical Point ◽  
Equilibrium Dynamics ◽  
Qcd Phase Diagram

scholarly journals Cooperatively rearranging regions change shape near the mode-coupling crossover for colloidal liquids on a sphere

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Navneet Singh ◽  
A. K. Sood ◽  
Rajesh Ganapathy
Keyword(s):  
Glass Transition ◽  
Mode Coupling ◽  
Three Dimensional ◽  
Order Theory ◽  
True Nature ◽  
Long Wavelength ◽  
Slowing Down ◽  
First Order Theory ◽  
Colloidal Liquids ◽  
Strong Curvature

Abstract The structure and dynamics of liquids on curved surfaces are often studied through the lens of frustration-based approaches to the glass transition. Competing glass transition theories, however, remain largely untested on such surfaces and moreover, studies hitherto have been entirely theoretical/numerical. Here we carry out single particle-resolved imaging of dynamics of bi-disperse colloidal liquids confined to the surface of a sphere. We find that mode-coupling theory well captures the slowing down of dynamics in the moderate to deeply supercooled regime. Strikingly, the morphology of cooperatively rearranging regions changed from string-like to compact near the mode-coupling crossover—a prediction unique to the random first-order theory of glasses. Further, we find that in the limit of strong curvature, Mermin–Wagner long-wavelength fluctuations are irrelevant and liquids on a sphere behave like three-dimensional liquids. A comparative evaluation of competing mechanisms is thus an essential step towards uncovering the true nature of the glass transition.

Annihilation of positrons in noble gases in the presence of an electric field

1982 ◽  
Vol 60 (12) ◽  
pp. 1717-1719
Author(s):  
P. U. Arifov ◽  
G. I. Zhuravleva
Keyword(s):  
Experimental Data ◽  
Elastic Scattering ◽  
Electric Field ◽  
Cross Sections ◽  
Noble Gases ◽  
Distribution Functions ◽  
Simultaneous Interpretation ◽  
Slowing Down ◽  
Speed Distribution ◽  
Scattering Cross Sections

The present article combines our earlier separate calculations of elastic scattering cross sections, annihilation parameters, and speed distribution functions of positrons slowing down in noble gases for the simultaneous interpretation of experimental data of both beam and drift experiments. Here we present the results on the calculations of phase shifts, annihilation parameter Z(k), speed distribution functions, and Zeff(F).

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