Ground State Instability in Non-relativistic QFT and Euler-Heisenberg Lagrangian via Holography

We study the ground state instability of a strongly coupled QFT with the $z=2$ Schr\"odinger symmetry in a constant electric field using probe branes holography. The system is $N_f$ $\mathcal{N}=2$ hypermultiplet fermions at zero charge density in the supergravity Schr\"odinger background. We show that the instability occurs due to Schwinger-like effect and an insulator state will undergo a transition to a conductor state. We calculate the decay rate of instability and pair production probability by using the $gauge/gravity$ duality. At zero temperature for massive fermions, we suggest that the instability occurs if the critical electric field is larger than the confining force between fermions, which is proportional to an effective mass. We demonstrate that, at zero temperature, the Schr\"odinger background simulates the role of a crystal lattice for massive particles. We also show that at finite 't Hooft coupling for particles with a mass higher than \frac{\sqrt{\lambda}}{\pi \b}, in this background, instability does not occur, no matter how large the external electric field is, meaning that we have a \textit{perfect insulator}. Moreover, we derive Euler-Heisenberg effective Lagrangian for the non-relativistic strongly correlated quantum theory from probe branes holography in Schr\"odinger spacetime.Comment: Prefect insulator discussed,typos fixed,added sections and citation

Equilibrium Instability of Chiral Mesons in External Electromagnetic Field via AdS/CFT

We study the equilibrium instability of chiral quarkonia in a plasma in the presence of constant magnetic and electric field and at finite axial chemical potential using AdS/CFT duality. The model in use is a supersymmetric QCD at large 't$\,$Hooft coupling and number of colors. We show that the presence of the magnetic field and the axial chemical potential even in the absence of the electric field make the system unstable. In a gapped system, a stable/unstable equilibrium state phase transition is observed and the initial transition amplitude of the equilibrium state to the non-equilibrium state is investigated. We demonstrate that at zero temperature and large magnetic field the instability grows linearly by increasing the quarkonium binding energy. In the constant electric and magnetic field, the system is in a equilibrium state if the Ohm's law and the chiral magnetic effect cancel their effects. This happens in a sub-space of $(E,B,T,\mu_5)$ space with constraint equation $\sigma_B B =- \sigma E$, where $\sigma$ and $\sigma_B$ are called electric and chiral magnetic conductivity, respectively. We analyze the decay rate of a gapless system when this constraint is slightly violated.Comment: 25 pages, 11 figure

Non-Equilibrium Critical Phenomena From Probe Brane Holography in Schr\"odinger Spacetime

We study the non-equilibrium steady-state phase transition from probe brane holography in $z=2$ Schr\"odinger spacetime. Concerning differential conductivity, a phase transition could occur in the conductor state. Considering constant current operator as the external field and the conductivity as an order parameter, we derive scaling behavior of order parameter near the critical point. We explore the critical exponents of the non-equilibrium phase transition in two different Schr\"odinger spacetimes, which originated $1)$ from supergravity, and $2)$ from AdS blackhole in the light-cone coordinates. Interestingly, we will see that even at the zero charge density, in our first geometry, the dynamical critical exponent of $z=2$ has a major effect on the critical exponents.Comment: 19 pages,10 figure

On AdS/CFT of Galilean Conformal Field Theories

We study a new contraction of a d+1 dimensional relativistic conformal algebra where n+1 directions remain unchanged. For n=0,1 the resultant algebras admit infinite dimensional extension containing one and two copies of Virasoro algebra, respectively. For n> 1 the obtained algebra is finite dimensional containing an so(2,n+1) subalgebra. The gravity dual is provided by taking a Newton-Cartan like limit of the Einstein's equations of AdS space which singles out an AdS_{n+2} spacetime. The infinite dimensional extension of n=0,1 cases may be understood from the fact that the dual gravities contain AdS_2 and AdS_3 factor, respectively. We also explore how the AdS/CFT correspondence works for this case where we see that the main role is playing by AdS_{n+2} base geometry.Comment: new references adde

Fermions in non-relativistic AdS/CFT correspondence

We extend the non-relativistic AdS/CFT correspondence to the fermionic fields. In particular we study the two point function of a fermionic operator in non-relativistic CFTs by making use of a massive fermion propagating in geometries with Schrodinger group isometry. Although the boundary of the geometries with Schrodinger group isometry differ from that in AdS geometries where the dictionary of AdS/CFT is established, using the general procedure of AdS/CFT correspondence, we see that the resultant two point function has the expected form for fermionic operators in non-relativistic CFTs, though a non-trivial regularization may be needed.Comment: 12 pages,Latex file; V2: typos corrected, refs adde

Neglected simultaneous bilateral femoral neck fractures secondary to narcotic drug abuse treated by bilateral one-staged hemiarthroplasty: a case report

Simultaneous bilateral femoral neck fractures are extremely rare and associated with various conditions. Up to now Most cases had correlations with major trauma, repetitive minor trauma, seizure, parathyroid or renal dysfunction, anti-epileptic medications, seizure, etc. A 28-year-old addict man referred to us with a 10-year history of narcotic drug abuse and history of 8 months bilateral groin pain. He admitted with displaced bilateral femoral neck fracture. Because of long duration of this condition and osteonecrosis revealed on bone scan, one-staged bilateral hip hemiarthroplasty was done. A good function was noted after surgery to 4-month follow up. Up to now, have not be founded in the literature that a case of bilateral femoral neck fracture associated with narcotic drug abuse

The Effect of Fiscal Decentralization on Under-five Mortality in Iran: A Panel Data Analysis

Background: Fiscal Decentralization (FD) in many cases is encouraged as a strong means of improving the efficiency and equity in the provision of public goods, such as healthcare services. This issue has urged the researchers to experimentally examine the relationship between fiscal decentralization indicators and health outcomes. In this study we examine the effect of Fiscal Decentralization in Medical Universities (FDMU) and Fiscal Decentralization in Provincial Revenues (FDPR) on Under-Five Mortality Rate (U5M) in provinces of Iran over the period between 2007 and 2010. Methods: We employed panel data methods in this article. The results of the Pesaran CD test demonstrated that most of the variables used in the analysis were cross-sectionally dependent. The Hausman test results suggested that fixed-effects were more appropriate to estimate our model. We estimated the fixed-effect model by using Driscoll-Kraay standard errors as a remedy for cross-sectional dependency. Results: According to the findings of this research, fiscal decentralization in the health sector had a negative impact on U5M. On the other hand, fiscal decentralization in provincial revenues had a positive impact on U5M. In addition, U5M had a negative association with the density of physicians, hospital beds, and provincial GDP per capita, but a positive relationship with Gini coefficient and unemployment. Conclusion: The findings of our study indicated that fiscal decentralization should be emphasized in the health sector. The results suggest the need for caution in the implementation of fiscal decentralization in provincial revenues