CRITICAL DIMENSIONS OF SYSTEMS WITH JOINT MULTICRITICAL AND LIFSHITZ-POINT-LIKE BEHAVIOR

2011 ◽  
Vol 25 (22) ◽  
pp. 1839-1845 ◽  
Author(s):  
ARTEM V. BABICH ◽  
LESYA N. KITCENKO ◽  
VYACHESLAV F. KLEPIKOV
Keyword(s):  
Field Theory ◽  
Critical Phenomena ◽  
Critical Points ◽  
Order Parameter ◽  
Mean Field Theory ◽  
Mean Field ◽  
Critical Dimensions ◽  
Lifshitz Point ◽  
The Mean ◽  
Derivatives Of

In this article, we consider a model that allows one to describe critical phenomena in systems with higher powers and derivatives of order parameter. The systems considered have critical points with joint multicritical and Lifshitz-point-like properties. We assess the lower and upper critical dimensions of these systems. These calculation enable us to find the fluctuation region where the mean field theory description does not work.

A QUANTUM SIMULATOR FOR PROBING MOTT LOBES VIA THE AC JOSEPHSON EFFECT

2013 ◽  
Vol 11 (05) ◽  
pp. 1350049
Author(s):  
MING-XIA HUO ◽  
YING LI ◽  
ZHI SONG ◽  
CHANG-PU SUN
Keyword(s):  
Field Theory ◽  
Order Parameter ◽  
Mean Field Theory ◽  
Mean Field ◽  
Finite Size ◽  
Weak Field ◽  
Josephson Current ◽  
Theory Approach ◽  
The Mean ◽  
Quantum Simulator

In this paper, we propose to directly detect Mott lobes, i.e. the order parameter 〈a〉, describing the Mott insulator (MI) to superfluid (SF) quantum phase transition of the Bose–Hubbard (BH) model. By weakly coupling the system to an environment in the SF phase, the U(1) symmetry breaking of the system is simulated, and the order parameter can be read from the AC Josephson current between the system and the environment. The relation between the order parameter and the Josephson current is obtained from both the mean-field theory approach and an exact numerical simulation of a finite-size example. Our numerical simulations show that the profile of the order parameter read from the Josephson current is different from it predicted by the mean-field theory, but similar to it in a system whose U(1) symmetry is broken by a weak field proportional to a + a†. This proposal is feasible in optical lattices.

scholarly journals Evidence of exactness of the mean-field theory in the nonextensive regime of long-range classical spin models

2000 ◽  
Vol 61 (17) ◽  
pp. 11521-11528 ◽  
Author(s):  
Sergio A. Cannas ◽  
A. C. N. de Magalhães ◽  
Francisco A. Tamarit
Keyword(s):  
Field Theory ◽  
Long Range ◽  
Mean Field Theory ◽  
Mean Field ◽  
Spin Models ◽  
Classical Spin ◽  
The Mean ◽  
Classical Spin Models

On the mean-field theory of spin glasses

1980 ◽  
Vol 13 (3) ◽  
pp. 403-418 ◽  
Author(s):  
A Blandin ◽  
M Gabay ◽  
T Garel
Keyword(s):  
Field Theory ◽  
Spin Glasses ◽  
Mean Field Theory ◽  
Mean Field ◽  
The Mean
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