9,584 research outputs found
Towards a complete classification of fermionic symmetry protected topological phases in 3D and a general group supercohomology theory
Classification and construction of symmetry protected topological (SPT)
phases in interacting boson and fermion systems have become a fascinating
theoretical direction in recent years. It has been shown that the (generalized)
group cohomology theory or cobordism theory can give rise to a complete
classification of SPT phases in interacting boson/spin systems. Nevertheless,
the construction and classification of SPT phases in interacting fermion
systems are much more complicated, especially in 3D. In this work, we revisit
this problem based on the equivalent class of fermionic symmetric local unitary
(FSLU) transformations. We construct very general fixed point SPT wavefunctions
for interacting fermion systems. We naturally reproduce the partial
classifications given by special group super-cohomology theory, and we show
that with an additional (the so-called
obstruction free subgroup of ) structure, a complete
classification of SPT phases for three-dimensional interacting fermion systems
with a total symmetry group can be obtained for
unitary symmetry group . We also discuss the procedure of deriving a
general group super-cohomology theory in arbitrary dimensions.Comment: 48 pages, 35 figures, published versio
Stable Large-Scale Perturbations in Interacting Dark-Energy Model
It is found that the evolutions of density perturbations on the super-Hubble
scales are unstable in the model with dark-sector interaction proportional
to the energy density of cold dark matter (CDM) and constant equation
of state parameter of dark energy . In this paper, to avoid the
instabilities, we suggest a new covariant model for the energy-momentum
transfer between DE and CDM. Then we show that the the large-scale
instabilities of curvature perturbations can be avoided in our model in the
universe filled only by DE and CDM. Furthermore, by including the additional
components of radiation and baryons, we calculate the dominant non-adiabatic
modes in the radiation era and find that the modes grow in the power law with
exponent at the order of unit.Comment: 14 pages, 2 figures. arXiv admin note: substantial text overlap with
arXiv:1110.180
Reentrant phase transitions and triple points of topological AdS black holes in Born-Infeld-massive gravity
Motivated by recent developments of black hole thermodynamics in de Rham,
Gabadadze and Tolley(dRGT) massive gravity, we study the critical behaviors of
four-dimensional topological Anti-de Sitter(AdS) black holes in the presence of
Born-Infeld nonlinear electrodynamics by treating the cosmological constant as
pressure and the corresponding conjugate quantity is interpreted as
thermodynamic volume. It shows that besides the Van der Waals-like SBH/LBH
phase transitions appears, the so-called reentrant phase transitions (RPTs) are
also observed when the coupling coefficients of massive potential and
Born-Infeld parameter satisfy some certain conditions.Comment: arXiv admin note: text overlap with arXiv:1612.08056; text overlap
with arXiv:1402.2837, arXiv:1306.5756 by other autho
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