5,877 research outputs found
Topological invariants for phase transition points of one-dimensional topological systems
We study topological properties of phase transition points of two
topologically non-trivial classes (D and DIII) in one dimension
by assigning a Berry phase defined on closed circles around the gap closing
points in the parameter space of momentum and a transition driving parameter.
While the topological property of the system is generally
characterized by a topological invariant, we identify that it
has a correspondence to the quantized Berry phase protected by the
particle-hole symmetry, and then give a proper definition of Berry phase to the
phase transition point. By applying our scheme to some specific models of class
D and DIII, we demonstrate that the topological phase transition can be well
characterized by the Berry phase of the transition point, which reflects the
change of Berry phases of topologically different phases across the phase
transition point.Comment: 6 pages, 5 figure
Winding numbers of phase transition points for one-dimensional topological systems
We study topological properties of phase transition points of one-dimensional
topological quantum phase transitions by assigning winding numbers defined on
closed circles around the gap closing points in the parameter space of momentum
and a transition driving parameter, which overcomes the problem of ill
definition of winding numbers on the transition points. By applying our scheme
to the extended Kitaev model and extended Su-Schrieffer-Heeger model, we
demonstrate that the topological phase transition can be well characterized by
winding numbers of transition points, which reflect the change of the winding
number of topologically different phases across the phase transition points.Comment: 5 pages, 5 figure
Limit on in Two Higgs Doublet Models
Using the recent CLEO measurement of , we find that the
branching ratio of cannot be larger than in two Higgs doublet
models. The small experimental value of can no longer be
explained by charged Higgs boson effects.Comment: 11 pages + 3 Figures (not included), ReVTeX, NTUTH-94-16 and
NHCU-HEP-94-1
Same-sign single dilepton productions at the LHC
We examine the same-sign single dilepton productions of
in high-energy proton-proton
collisions at the Large Hadron Collider (LHC) in models with doubly charged
Higgs scalars as well as heavy Majorana neutrinos. We demonstrate that these
spectacular productions can be detected at the LHC for a class model in which
the doubly charged Higgs scalars couple only to the right-handed charged
leptons. The ranges of the possible doubly charged Higgs masses and mixings to
observe the processes at the LHC are discussed.Comment: 10 pages, 5 figure
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