A. Montakhab | Searcharxiv

arXiv2021

Holographic paramagnetic-ferromagnetic phase transition of Power-Maxwell-Gauss-Bonnet black holes

Based on the shooting method, we numerically investigate the properties of holographic paramagnetism-ferromagnetism phase transition in the presence of higher order Gauss-Bonnet (\emph{GB}) correction terms on the gravity side. On the matter field side, however, we consider the effects of the Power-Maxwell (\emph{PM}) nonlinear electrodynamics on the phase transition of this system. For this purpose, we introduce a massive $2-$form coupled to \emph{PM} field, and neglect the effects of $2-$form fields and gauge field on the background geometry. We observe that increasing the strength of both the power parameter $q$ and \emph{GB} coupling constant $α$ decrease the critical temperature of the holographic model, and lead to the harder formation of magnetic moment in the black hole background. Interestingly, we find out that at low temperatures, the spontaneous magnetization and ferromagnetic phase transition happen in the absence of external magnetic field. In this case, the critical exponent for magnetic moment has the mean field value, $1/2$, regardless of the values of $q$ and $α$. In the presence of external magnetic field, however, the magnetic susceptibility satisfies the Curie-Weiss law.

hep-th↗

arXiv2016

Relativistic three-partite non-locality

Bell-like inequalities have been used in order to distinguish non-local quantum pure states by various authors. The behavior of such inequalities under Lorentz transformation has been a source of debate and controversies in the past. In this paper, we consider the two most commonly studied three-particle pure states, that of W and GHZ states which exhibit distinctly different type of entanglement. We discuss the various types of three-particle inequalities used in previous studies and point to their corresponding shortcomings and strengths. Our main result is that if one uses Czachor's relativistic spin operator and Svetlichny's inequality as the main measure of non-locality and uses the same angles in the rest frame ($S$) as well as the moving frame ($S^{\prime}$), then maximally violated inequality in $S$ will decrease in the moving frame, and will eventually lead to lack of non-locality ( i.e. satisfaction of inequality) in the $v \rightarrow c$ limit. This is shown for both the GHZ and W states and in two different configurations which are commonly studied (\textbf{Case $I$} and \textbf{Case $II$}). Our results are in line with a more familiar case of two particle case. We also show that the satisfaction of Svetlichny's inequality in the $v\rightarrow c$ limit is independent of initial particles' velocity. Our study shows that whenever we use Czachor's relativistic spin operator, results draws a clear picture of three-particle non-locality making its general properties consistent with previous studies on two-particle systems regardless of the W state or the GHZ state is involved.....

physics.gen-ph↗