Novel duality in disorder driven local quantum criticality

We find that competition between random Kondo and random magnetic correlations results in a quantum phase transition from a local Fermi liquid to a spin liquid. The local charge susceptibility turns out to have exactly the same critical exponent as the local spin susceptibility, suggesting novel duality between the Kondo singlet phase and the critical local moment state beyond the Landau-Ginzburg-Wilson symmetry breaking framework. This leads us to propose an enhanced symmetry at the local quantum critical point, described by an O(4) vector for spin and charge. The symmetry enhancement serves mechanism of electron fractionalization in critical impurity dynamics, where such fractionalized excitations are identified with topological excitations

Spin liquids in graphene

We reveal that local interactions in graphene allow novel spin liquids between the semi-metal and antiferromagnetic Mott insulating phases, identified with algebraic spin liquid and Z$_{2}$ spin liquid, respectively. We argue that the algebraic spin liquid can be regarded as the two dimensional realization of one dimensional spin dynamics, where antiferromagnetic correlations show exactly the same power-law dependence as valence bond correlations. Nature of the Z$_{2}$ spin liquid turns out to be $d + i d'$ singlet pairing, but time reversal symmetry is preserved, taking $d + i d'$ in one valley and $d - i d'$ in the other valley. We propose the quantized thermal valley Hall effect as an essential feature of this gapped spin liquid state. Quantum phase transitions among the semi-metal, algebraic spin liquid, and Z$_{2}$ spin liquid are shown to be continuous while the transition from the Z$_{2}$ spin liquid to the antiferromagnetic Mott insulator turns out to be the first order. We emphasize that both algebraic spin liquid and $d \pm id'$ Z$_{2}$ spin liquid can be verified by the quantum Monte Carlo simulation, showing the enhanced symmetry in the algebraic spin liquid and the quantized thermal valley Hall effect in the Z$_{2}$ spin liquid

Black Hole Mergers in Galactic Nuclei Induced by the Eccentric Kozai-Lidov Effect

Nuclear star clusters around massive black holes are expected to be abundant in stellar mass black holes and black hole binaries. These binaries form a hierarchical triple system with the massive black hole at the center. Gravitational perturbations from the massive black hole can cause high eccentricity excitation. During this process, the eccentricity may approach unity, and the pericenter distance may become sufficiently small that gravitational wave emission drives the binary to merge. In this paper, we consider a simple proof of concept and explore the effect of the eccentric Kozai-Lidov mechanism for unequal mass binaries. We perform a set of Monte Carlo simulations on BH-BH binaries in galactic nuclei with quadrupole and octupole-level secular perturbations, general relativistic precession, and gravitational wave emission. For a nominal number of steady-state BH-BH binaries, our model gives a total merger rate $\sim 1 - 3$$Gpc^{-3} yr^{-1}$, depending on the assumed density profile. Thus, our model potentially competes with other dynamical mechanisms, such as the dynamical formations and mergers of BH binaries in globular clusters or dense nuclear clusters without a massive black hole. We provide predictions for the distributions of these LIGO sources in galactic nuclei.Comment: 10 pages, 12 figures, accepted to Ap

Strategic Recommendations for New PAs entering the Workforce in 2020-2025

The current climate of job market favors the physician assistant profession, and the trends indicate that it will continue to do so well into the near future. These opportunities do not come without challenges from other factors facing the market, and new PAs need to be aware of them and work to find ways to actively compete against them. Understanding the effectiveness and efficiency of their profession and how they perform when pitched against NPs in medicine can help PAs secure a job with an employer who are choosing between hiring one and not the other. Once hired, being involved with the innovation portfolio within their organizations, can help open new opportunities for PAs to build their careers