48 research outputs found
Three phase traffic theory
Abstract In the three phase theory, the traffic phenomena are explained by three phase theory: free flow, synchronized flow, and moving jam. Here, this paper introduces the concept of each phase. Moreover, the paper explains the process of the phase transition. The three phase traffic theory offers qualitative explanation of real traffic
Triplet-Superconductivity in Triple-Band Crossings
Multi-band superconductivity in topological semimetals are the paradigms of
unconventional superconductors. Their exotic gap structures and topological
properties have fascinated searching for material realizations and
applications. In this paper, we focus on triple point fermions, a new type of
band crossings, and we claim that their superconductivity uniquely stabilizes
spin-triplet pairing. Unlike conventional superconductors and other multi band
superconductors, such triplet superconductivity is the novel phenomena of
triple point fermions where the spin-singlet pairing is strictly forbidden in
the on-site interaction due to the Fermi statistics. We find that two distinct
triplet superconductors, characterized by the presence and absence of
time-reversal symmetry, are allowed which in principle can be controlled by
tuning the chemical potential. For the triplet superconductor with
time-reversal symmetry, we show that topologically protected nodal lines are
realized. In contrast, for time-reversal broken case, the complication of
topologically protected Bogoliubov Fermi surfaces emerges. Our theoretical
study provides a new guidance for searching triplet superconductivities and
their exotic implications.Comment: 7 pages, 3 figure
Modular Anomalies in (2+1) and (3+1)-D Edge Theories
The classification of topological phases of matter in the presence of
interactions is an area of intense interest. One possible means of
classification is via studying the partition function under modular transforms,
as the presence of an anomalous phase arising in the edge theory of a
D-dimensional system under modular transformation, or modular anomaly, signals
the presence of a (D+1)-D non-trivial bulk. In this work, we discuss the
modular transformations of conformal field theories along a (2+1)-D and a
(3+1)-D edge. Using both analytical and numerical methods, we show that chiral
complex free fermions in (2+1)-D and (3+1)-D are modular invariant. However, we
show in (3+1)-D that when the edge theory is coupled to a background U(1) gauge
field this results in the presence of a modular anomaly that is the
manifestation of a quantum Hall effect in a (4+1)-D bulk. Using the modular
anomaly, we find that the edge theory of (4+1)-D insulator with spacetime
inversion symmetry(P*T) and fermion number parity symmetry for each spin
becomes modular invariant when 8 copies of the edges exist