3,055 research outputs found
Loop optimization for tensor network renormalization
We introduce a tensor renormalization group scheme for coarse-graining a
two-dimensional tensor network that can be successfully applied to both
classical and quantum systems on and off criticality. The key innovation in our
scheme is to deform a 2D tensor network into small loops and then optimize the
tensors on each loop. In this way, we remove short-range entanglement at each
iteration step and significantly improve the accuracy and stability of the
renormalization flow. We demonstrate our algorithm in the classical Ising model
and a frustrated 2D quantum model.Comment: 15 pages, 11 figures, accepted version for Phys. Rev. Let
Universal linear-temperature resistivity: possible quantum diffusion transport in strongly correlated superconductors
The strongly correlated electron fluids in high temperature cuprate
superconductors demonstrate an anomalous linear temperature () dependent
resistivity behavior, which persists to a wide temperature range without
exhibiting saturation. As cooling down, those electron fluids lose the
resistivity and condense into the superfluid. However, the origin of the
linear- resistivity behavior and its relationship to the strongly correlated
superconductivity remain a mystery. Here we report a universal relation
, which bridges the slope of the
linear--dependent resistivity () to the London penetration depth
at zero temperature among cuprate superconductor
BiSrCaCuO and heavy fermion superconductors
CeCoIn, where is vacuum permeability, is the Boltzmann
constant and is the reduced Planck constant. We extend this scaling
relation to different systems and found that it holds for other cuprate,
pnictide and heavy fermion superconductors as well, regardless of the
significant differences in the strength of electronic correlations, transport
directions, and doping levels. Our analysis suggests that the scaling relation
in strongly correlated superconductors could be described as a hydrodynamic
diffusive transport, with the diffusion coefficient () approaching the
quantum limit , where is the quasi-particle effective
mass.Comment: 8 pages, 2 figures, 1 tabl
Leptophilic dark matter in gauged model in light of DAMPE cosmic ray excess
Motivated by the very recent cosmic-ray electron+positron excess observed by
DAMPE collaboration, we investigate a Dirac fermion dark matter (DM) in the
gauged model. DM interacts with the electron and muon via the
gauge boson . The model can explain the DAMPE data well.
Although a non-zero DM-nucleon cross section is only generated at one loop
level and there is a partial cancellation between and
couplings, we find that a large portion of mass is ruled out from
direct DM detection limit leaving the allowed mass to be close to two
times of the DM mass. Implications for and , and muon anomaly are also studied.Comment: Discussions added, version accepted by EPJ
The single charmed pentaquark molecular states via the QCD sum rules
In this work, we systematically investigate the singly charmed pentaquark
molecular states , and with
the QCD sum rules by carrying out the operator product expansion up to the
vacuum condensates of dimension 13 and taking fully account of the light-flavor
breaking effects. The numerical results favor assigning the
as the molecular state with the and
, assigning the as the
molecular state with the and , assigning the as the molecular state with the
and , and assigning the
as the molecular state with the
and . Other potential
molecule candidates are also predicted, which may be observed in future
experiments. For example, we can search for the and molecular
states with the isospin in the
and mass spectrum respectively in the
future, which could shed light on the nature of the .Comment: 20 pages, 6 figure
On Nonuniform Polynomial Trichotomy of Linear Discrete-Time Systems in Banach Spaces
We study two nonuniform polynomial trichotomy concepts for linear
discrete-time systems in Banach spaces. Our main objective is to give summation property for
nonuniform polynomial trichotomies. As for applications we obtain characterization of these
concepts in terms of Lyapunov functions
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