scholarly journals On fast and slow Earth’s magnetospheric dynamics during geomagnetic storms: a stochastic Langevin approach

2018 ◽  
Vol 8 ◽  
pp. A56 ◽  
Author(s):  
Tommaso Alberti ◽  
Giuseppe Consolini ◽  
Paola De Michelis ◽  
Monica Laurenza ◽  
Maria Federica Marcucci
Keyword(s):  
Geomagnetic Storms ◽  
State Function ◽  
Topological Phase ◽  
H Index ◽  
First Order ◽  
Topological Phase Transition ◽  
Multiscale Dynamics ◽  
Wide Range ◽  
Langevin Approach ◽  
State Functions

The Earth’s magnetosphere responds to the external changes of interplanetary magnetic field and solar wind conditions showing a multiscale dynamics, manifesting in the occurrence of fluctuations over a very wide range of timescales. Here, using an approach based on a Langevin/Fokker-Planck description we investigate the nature of the fast (short-) and slow (long-timescale) fluctuations of SYM-H index during geomagnetic storms. The results point towards a different origin of the fast (τ < 200 min) and slow (τ > 200 min) fluctuations, which are characterized by state functions of different nature. In detail, the state function associated with the slow dynamics shows the evidence of the occurrence of first-order-like topological phase transition during the different phases of a geomagnetic storm, while the fast dynamics seems to be characterized by a quasi-invariant quadratic state function. A modeling in terms of stochastic Langevin equation is discussed and the relevance of our results in the framework of Space Weather studies is outlined.

Topological phase transition in asymmetric nuclear matter

2014 ◽  
Vol 23 (05) ◽  
pp. 1450031
Author(s):  
Tran Huu Phat ◽  
Nguyen Van Thu
Keyword(s):  
Phase Transition ◽  
Nuclear Matter ◽  
Critical Point ◽  
Fermi Liquid ◽  
Chemical Potential ◽  
Topological Phase ◽  
Baryon Chemical Potential ◽  
Asymmetric Nuclear Matter ◽  
First Order ◽  
Topological Phase Transition

Starting from an effective model of asymmetric nuclear matter we show that at finite temperature T and baryon chemical potential μB there exists a topological phase transition from state of non-Fermi liquid to that of Fermi liquid which is protected by winding numbers. At low μB the transition is first-order, then extends to a second-order phase transition at larger μB through a tri-critical point. The isospin dependences of the tri-critical point and the phase diagram in the (T, μB)-plane are established. The distinction between this type of phase transition and the similar phenomenon caused by the Silver Blaze property (SBP) at T = 0 is confirmed for isospin varying from 0 to 1. We reveal that the topological phase transition could emerge in a large class of nuclear theories.

scholarly journals Topological phase transition between a normal insulator and a topological metal state in a quasi-one-dimensional system

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Milad Jangjan ◽  
Mir Vahid Hosseini
Keyword(s):  
Phase Transition ◽  
Dimensional System ◽  
Inversion Symmetry ◽  
Topological Phase ◽  
Edge States ◽  
Zero Energy ◽  
One Dimensional ◽  
Topological Phase Transition ◽  
Metal State ◽  
Topological Metal

AbstractWe theoretically report the finding of a new kind of topological phase transition between a normal insulator and a topological metal state where the closing-reopening of bandgap is accompanied by passing the Fermi level through an additional band. The resulting nontrivial topological metal phase is characterized by stable zero-energy localized edge states that exist within the full gapless bulk states. Such states living on a quasi-one-dimensional system with three sublattices per unit cell are protected by hidden inversion symmetry. While other required symmetries such as chiral, particle-hole, or full inversion symmetry are absent in the system.

scholarly journals Topological Phase Transition and Phonon-Space Dirac Topology Surfaces in ZrTe5

2021 ◽  
Vol 126 (1) ◽  
Author(s):  
Niraj Aryal ◽  
Xilian Jin ◽  
Q. Li ◽  
A. M. Tsvelik ◽  
Weiguo Yin
Keyword(s):  
Phase Transition ◽  
Topological Phase ◽  
Topological Phase Transition

scholarly journals Decay of the Dst field of geomagnetic disturbance after substorm onset and its implication to storm-substorm relation

1996 ◽  
Vol 14 (6) ◽  
pp. 608-618 ◽  
Author(s):  
T. Iyemori ◽  
D. R. K. Rao
Keyword(s):  
Ring Current ◽  
Geomagnetic Storms ◽  
Sharp Decrease ◽  
Geomagnetic Disturbance ◽  
Substorm Onset ◽  
Significant Development ◽  
H Index ◽  
Magnetospheric Tail ◽  
Storms And Substorms ◽  
Substorm Onsets

Abstract. In order to investigate the causal relationship between magnetic storms and substorms, variations of the mid-latitude geomagnetic indices, ASY (asymmetric part) and SYM (symmetric part), at substorm onsets are examined. Substorm onsets are defined by three different phenomena; (1) a rapid increase in the mid-latitude asymmetric-disturbance indices, ASY-D and ASY-H, with a shape of so-called `mid-latitude positive bay\\'; (2) a sharp decrease in the AL index; (3) an onset of Pi2 geomagnetic pulsation. The positive bays are selected using eye inspection and a pattern-matching technique. The 1-min-resolution SYM-H index, which is essentially the same as the hourly Dst index except in terms of the time resolution, does not show any statistically significant development after the onset of substorms; it tends to decay after the onset rather than to develop. It is suggested by a simple model calculation that the decay of the magnetospheric tail current after substorm onset is responsible for the decay of the Dst field. The relation between the IMF southward turning and the development of the Dst field is re-examined. The results support the idea that the geomagnetic storms and substorms are independent processes; that is, the ring-current development is not the result of the frequent occurrence of substorms, but that of enhanced convection caused by the large southward IMF. A substorm is the process of energy dissipation in the magnetosphere, and its contribution to the storm-time ring-current formation seems to be negligible. The decay of the Dst field after a substorm onset is explained by a magnetospheric energy theorem.

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