Mott insulating states of the anisotropic SU(4) Dirac fermions

We investigate the Mott insulating states of the SU(4) Hubbard model on the square lattice with a staggered pattern of flux by employing the large-scale sign-problem free quantum Monte-Carlo simulations. As varying the flux $\phi$, the low energy fermions evolve from a nested Fermi surface at zero flux to isotropic Dirac cones at $\pi$-flux, and exhibit anisotropic Dirac cones in between. The simulations show the competitions among the Dirac semi-metal, the antiferromagnetic and valence-bond-solid phases. The phase diagram features a tri-critical point where these three phases meet. In the strong coupling limit, only the antiferromagnetic phase appears. The quantum phase transition between the antiferromagnetic phase and the valence-bond-solid phase is found to be continuous, and the critical exponents are numerically determined. We have also found that inside the valence-bond-solid phase, there exists a region that the single-particle gap vanishes but the spin gap remains finite, which is consistent with a plaquette valence-bonding ordering pattern.Comment: 6 pages, 7 figure

Quantum Monte Carlo simulations of the attractive SU(3) Hubbard model on a honeycomb lattice

We perform the projector quantum Monte Carlo simulation of the half-filled attractive SU(3) Hubbard model on a honeycomb lattice, exploring the effects of SU(3) symmetry on the correlated attractive Dirac fermions. Our simulation indicates the absence of pairing order in the system and shows a quantum phase transition from the semimetal to charge density wave (CDW) at the critical point $U_c=-1.52(2)$. We demonstrate that this quantum phase transition belongs to the chiral Ising universality class according to the numerically determined critical exponents $\nu=0.82(3)$ and $\eta=0.58(4)$. With the increase of coupling strength, the trion formation is investigated, and the change in probability of the on-site trion occupancy infers the coexistence of on-site trionic and off-site trionic CDW states at half-filling.Comment: 12 pages, 12 figure

Effect of renin-angiotensin system inhibitors on acute kidney injury among patients undergoing cardiac surgery: A review and meta-analysis

10.1053/j.semtcvs.2020.11.024SEMINARS IN THORACIC AND CARDIOVASCULAR SURGERY3341014-102

Adversarial Attack on Community Detection by Hiding Individuals

It has been demonstrated that adversarial graphs, i.e., graphs with imperceptible perturbations added, can cause deep graph models to fail on node/graph classification tasks. In this paper, we extend adversarial graphs to the problem of community detection which is much more difficult. We focus on black-box attack and aim to hide targeted individuals from the detection of deep graph community detection models, which has many applications in real-world scenarios, for example, protecting personal privacy in social networks and understanding camouflage patterns in transaction networks. We propose an iterative learning framework that takes turns to update two modules: one working as the constrained graph generator and the other as the surrogate community detection model. We also find that the adversarial graphs generated by our method can be transferred to other learning based community detection models.Comment: In Proceedings of The Web Conference 2020, April 20-24, 2020, Taipei, Taiwan. 11 page