8,950 research outputs found
Nature of the Quantum Phase Transition in Quantum Compass Model
In this work, we show that the quantum compass model on an square lattice can
be mapped to a fermionic model with local density interaction. We introduce a
mean-field approximation where the most important fluctuations, those
perpendicular to the ordering direction, are taken into account exactly. It is
found that the quantum phase transition point at marks a first order
phase transition. We also show that the mean field result is robust against the
remaining fluctuation corrections up to the second order.Comment: 7 pages, 10 fig
Disodium dihydrogen pyridine-2,3,5,6-tetraÂcarboxylÂate trihydrate
In the title compound, 2Na+·C9H3NO8
2−·3H2O, the asymmetric unit consists of two Na+ cations, one dihydrogen pyridine-2,3,5,6-tetraÂcarboxylÂate dianion (H2pdtc2−) and three water molÂecules coordinated to the Na+ cations. The configuration of the anion is stabilized by intramolecular O—H⋯O hydrogen bonding between vicinal carboxylate/carboxy groups. The Na+ cations are bridged by the H2pdtc2− dianions, generating layers extending infinitely in sheets parallel to (001), and further pillared by the water molÂecule linkers to build up a three-dimensional framework
Glueball Masses from Hamiltonian Lattice QCD
We calculate the masses of the , and glueballs from
QCD in 3+1 dimensions using an eigenvalue equation method for Hamiltonian
lattice QCD developed and described elsewhere by the authors. The mass ratios
become approximately constants in the coupling region ,
from which we estimate and
.Comment: 12 pages, Latex, figures to be sent upon reques
Interaction-driven topological and nematic phases on the Lieb lattice
We show that topological states are often developed in two-dimensional semimetals with quadratic band crossing points (BCPs) by electron–electron interactions. To illustrate this, we construct a concrete model with the BCP on an extended Lieb lattice and investigate the interaction-driven topological instabilities. We find that the BCP is marginally unstable against infinitesimal repulsions. Depending on the interaction strengths, topological quantum anomalous/spin Hall, charge nematic, and nematic-spin-nematic phases develop separately. Possible physical realizations of quadratic BCPs are provided
Effect of magnetic field correlation length on the gamma-ray pulsar halo morphology under anisotropic diffusion
Anisotropic diffusion is one of the potential interpretations for the
morphology of the Geminga pulsar halo. It interprets the observed
slow-diffusion phenomenon through a geometric effect, assuming the mean
magnetic field direction around Geminga is closely aligned with the line of
sight toward it. However, this direction should not extend further than the
correlation length of the turbulent magnetic field , which could be
pc or less. We first revisit the scenario and show that the halo
asymmetry predicted by this scenario is mainly contributed by the electrons
located beyond the ``core" section around Geminga, which has a length of
pc. Then, considering the directional variation of the magnetic field beyond
the core section, we take one magnetic field configuration as an example to
investigate the possible halo morphology. The predicted morphology has some
different features compared to the scenario. The current
experiments may already be able to test these features. In addition, we use a
semi-analytical method to solve the anisotropic propagation equation, which
offers significant convenience compared to numerical approaches.Comment: 15 pages, 7 figure
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