55,027 research outputs found
Associated Production of Neutral Higgs Boson with Squark Pair in the Minimal Supersymmetric Standard Model with Explicit CP Violation at the CERN LHC
We investigate the associated production of neutral Higgs boson with squark
pair in the minimal supersymmetric standard model with and without explicit CP
violation, respectively. We show that the dominant productions in both cases
are always ones of the lightest neutral Higgs boson associated with the
lightest stop pair, which can reach a few pb, in the ranges of parameters
allowed by constraints from the electric dipole moment experiments. In most of
the parameter space, the total cross sections in the case with explicit CP
violation are significantly enhanced, compared with ones without explicit CP
violation. For some special parameters, several orders of magnitude enhancement
can be obtained.Comment: 4 pages, 7 figures, version to appear in PR
Quantum phase transition in a three-level atom-molecule system
We adopt a three-level bosonic model to investigate the quantum phase
transition in an ultracold atom-molecule conversion system which includes one
atomic mode and two molecular modes. Through thoroughly exploring the
properties of energy level structure, fidelity, and adiabatical geometric
phase, we confirm that the system exists a second-order phase transition from
an atommolecule mixture phase to a pure molecule phase. We give the explicit
expression of the critical point and obtain two scaling laws to characterize
this transition. In particular we find that both the critical exponents and the
behaviors of ground-state geometric phase change obviously in contrast to a
similar two-level model. Our analytical calculations show that the ground-state
geometric phase jumps from zero to ?pi/3 at the critical point. This
discontinuous behavior has been checked by numerical simulations and it can be
used to identify the phase transition in the system.Comment: 8 pages,8 figure
Quantum Phase Transition in Hall Conductivity on an Anisotropic Kagome Lattice
We study the quantum Hall effect(QHE) on the Kagom\'{e} lattice with
anisotropy in one of the hopping integrals. We find a new type of QHE
characterized by the quantization rules for Hall conductivity
and Landau Levels ( is an integer), which is different from any known type. This phase
evolves from the QHE phase with and in the isotropic case, which is realized in a system
with massless Dirac fermions (such as in graphene). The phase transition does
not occur simultaneously in all Hall plateaus as usual but in sequence from low
to high energies, with the increase of hopping anisotropy.Comment: 5 pages, 4 figure
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