XY criticality arising from emergent symmetry in the three-dimensional Ashkin-Teller model.

The Ashkin-Teller model plays a central role in studying the phase transitions of statistical mechanics models and condensed matter systems. Nevertheless, the phase transitions of the three-dimensional Ashkin-Teller model with competing interactions have long been an enigma. Here, we employ a methodology conceptually based on emergent symmetry and perform embedding cluster Monte Carlo simulations for unprecedentedly large systems.

Emergent Nambu-Goldstone phase of Z_{q} model from dynamics.

Using extensive simulations, we study the dynamic critical phenomena of the Z_{q} model in an oscillating field. We find Berezinskii-Kosterlitz-Thouless transitions for q=6 in two dimensions and a first-order transition for q=3 in three dimensions, hence the equilibrium-nonequilibrium correspondence is conditionally validated. Surprisingly, the correspondence is apparently violated at q=5, 6, and 7 in three dimensions, for which the equilibrium and nonequilibrium scenarios feature a single transition and two transitions, respectively.

Extraordinary-log Universality of Critical Phenomena in Plane Defects.

The recent discovery of the extraordinary-log (E-Log) criticality is a celebrated achievement in modern critical theory and calls for generalization. Using large-scale Monte Carlo simulations, we study the critical phenomena of plane defects in three- and four-dimensional O(n) critical systems. In three dimensions, we provide the first numerical proof for the E-Log criticality of plane defects.

Extraordinary-Log Surface Phase Transition in the Three-Dimensional XY Model.

Universality is a pillar of modern critical phenomena. The standard scenario is that the two-point correlation algebraically decreases with the distance r as g(r)∼r^{2-d-η}, with d the spatial dimension and η the anomalous dimension. Very recently, a logarithmic universality was proposed to describe the extraordinary surface transition of the O(N) system.

History-dependent percolation in two dimensions.

We study the history-dependent percolation in two dimensions, which evolves in generations from standard bond-percolation configurations through iteratively removing occupied bonds. Extensive simulations are performed for various generations on periodic square lattices up to side length L=4096. From finite-size scaling, we find that the model undergoes a continuous phase transition, which, for any finite number of generations, falls into the universality of standard two-dimensional (2D) percolation.

Finite-size scaling of O() systems at the upper critical dimensionality.

Logarithmic finite-size scaling of the O() universality class at the upper critical dimensionality ( = 4) has a fundamental role in statistical and condensed-matter physics and important applications in various experimental systems. Here, we address this long-standing problem in the context of the -vector model ( = 1, 2, 3) on periodic four-dimensional hypercubic lattices. We establish an explicit scaling form for the free-energy density, which simultaneously consists of a scaling term for the Gaussian fixed point and another term with multiplicative logarithmic corrections.

Unique Landau-level structure of monolayer black phosphorus under an exponentially decaying magnetic field.

We study the Landau-level spectrum of a monolayer black phosphorus under an exponentially decaying magnetic field along one spatial dimension. The results show that unlike the case in a constant magnetic field, the number of Landau levels in the inhomogeneous magnetic field is finite, and the Landau-level structure of the system is strongly dependent on the inhomogeneity of the magnetic field. In particular, the crossing of some Landau levels apparently occurs, and the accidental degeneracy points between the levels for the conduction and valence bands are highly anisotropic due to the anisotropic effective masses in monolayer black phosphorus.

Duality and the universality class of the three-state Potts antiferromagnet on plane quadrangulations.

We provide a criterion based on graph duality to predict whether the three-state Potts antiferromagnet on a plane quadrangulation has a zero- or finite-temperature critical point, and its universality class. The former case occurs for quadrangulations of self-dual type, and the zero-temperature critical point has central charge c=1. The latter case occurs for quadrangulations of non-self-dual type, and the critical point belongs to the universality class of the three-state Potts ferromagnet.

Coulomb Liquid Phases of Bosonic Cluster Mott Insulators on a Pyrochlore Lattice.

Employing large-scale quantum Monte Carlo simulations, we reveal the full phase diagram of the extended Hubbard model of hard-core bosons on the pyrochlore lattice with partial fillings. When the intersite repulsion is dominant, the system is in a cluster Mott insulator phase with an integer number of bosons localized inside the tetrahedral units of the pyrochlore lattice. We show that the full phase diagram contains three cluster Mott insulator phases with 1/4, 1/2, and 3/4 boson fillings, respectively.

[Measurement of myeloid-derived suppressor cells and T-helper 17 cells in peripheral blood of young children with recurrent wheezing].

Objective: To determine the frequencies and significance of myeloid-derived suppressor cells (MDSCs) and T-helper 17 (Th17) cells in peripheral blood of young children with recurrent wheezing.

Methods: Thirty young children with an acute exacerbation of recurrent wheezing were randomly enrolled. Twenty age-matched children with bronchopneumonia (pneumonia group) and 23 age-matched preoperative children with non-infectious or non-neoplastic diseases (hernia or renal calculus) (control group) were selected.

Scaling of cluster heterogeneity in the two-dimensional Potts model.

Cluster heterogeneity, the number of clusters of mutually distinct sizes, has been recently studied for explosive percolation and standard percolation [H. K. Lee et al.

Testing a model with an extended O(2) symmetry in two and three dimensions.

We investigate a model with an extended O(2) symmetry in two and three dimensions, using the combination of extensive Monte Carlo simulations and the finite-size scaling. On this basis, we establish rich phase diagrams, which are constituted by O(2) critical lines. From various prospectives, the ordered states on the phase diagrams can be classified into intraspecies and interspecies correlated phases, quasi-long-range and long-range ordered phases, or ferromagnetic and antiferromagnetic phases.

Worm-type Monte Carlo simulation of the Ashkin-Teller model on the triangular lattice.

We investigate the symmetric Ashkin-Teller (AT) model on the triangular lattice in the antiferromagnetic two-spin coupling region (J<0). In the J→-∞ limit, we map the AT model onto a fully packed loop-dimer model on the honeycomb lattice. On the basis of this exact transformation and the low-temperature expansion, we formulate a variant of worm-type algorithms for the AT model, which significantly suppress the critical slowing down.