20,281 research outputs found
Particle-hole symmetry and interaction effects in the Kane-Mele-Hubbard model
We prove that the Kane-Mele-Hubbard model with purely imaginary
next-nearest-neighbor hoppings has a particle-hole symmetry at half-filling.
Such a symmetry has interesting consequences including the absence of charge
and spin currents along open edges, and the absence of the sign problem in the
determinant quantum Monte-Carlo simulations. Consequentially, the interplay
between band topology and strong correlations can be studied at high numeric
precisions. The process that the topological band insulator evolves into the
antiferromagnetic Mott insulator as increasing interaction strength is studied
by calculating both the bulk and edge electronic properties. In agreement with
previous theory analyses, the numeric simulations show that the
Kane-Mele-Hubbard model exhibits three phases as increasing correlation
effects: the topological band insulating phase with stable helical edges, the
bulk paramagnetic phase with unstable edges, and the bulk antiferromagnetic
phase
Temperature-dependent Cross Sections for Charmonium Dissociation in Collisions with Pions and Rhos in Hadronic Matter
Meson-charmonium dissociation reactions governed by the quark interchange are
studied with temperature-dependent quark potentials. Quark-antiquark
relative-motion wave functions and masses of charmonia and charmed mesons are
determined by the central spin-independent part of the potentials or by the
central spin-independent part and a smeared spin-spin interaction. The
prominent temperature dependence of the masses is found. Based on the
potentials, the wave functions, and the meson masses, we obtain
temperature-dependent cross sections for fifteen pion-charmonium and
rho-charmonium dissociation reactions. The numerical cross sections are
parametrized for future applications in hadronic matter. The particular
temperature dependence of the J/psi bound state leads to unusual behavior of
the cross sections for endothermic J/psi dissociation reactions. The quantum
numbers of psi' and chi_c can not make their difference in mass in the
temperature region 0.6T_c < T < T_c, but can make the psi' dissociation
different from the chi_c dissociation.Comment: 52 pages, 23 figures, 6 table
Error-driven Global Transition in a Competitive Population on a Network
We show, both analytically and numerically, that erroneous data transmission
generates a global transition within a competitive population playing the
Minority Game on a network. This transition, which resembles a phase
transition, is driven by a `temporal symmetry breaking' in the global outcome
series. The phase boundary, which is a function of the network connectivity
and the error probability , is described quantitatively by the
Crowd-Anticrowd theory.Comment: 4 pages, 3 figure
Internal character dictates phase transition dynamics between isolation and cohesive grouping
We show that accounting for internal character among interacting,
heterogeneous entities generates rich phase transition behavior between
isolation and cohesive dynamical grouping. Our analytical and numerical
calculations reveal different critical points arising for different
character-dependent grouping mechanisms. These critical points move in opposite
directions as the population's diversity decreases. Our analytical theory helps
explain why a particular class of universality is so common in the real world,
despite fundamental differences in the underlying entities. Furthermore, it
correctly predicts the non-monotonic temporal variation in connectivity
observed recently in one such system
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