7,428 research outputs found
Crossover from a pseudogap state to a superconducting state
On the basis of our calculation we deduce that the particular electronic
structure of cuprate superconductors confines Cooper pairs to be firstly formed
in the antinodal region which is far from the Fermi surface, and these pairs
are incoherent and result in the pseudogap state. With the change of doping or
temperature, some pairs are formed in the nodal region which locates the Fermi
surface, and these pairs are coherent and lead to superconductivity. Thus the
coexistence of the pseudogap and the superconducting gap is explained when the
two kinds of gaps are not all on the Fermi surface. It is also shown that the
symmetry of the pseudogap and the superconducting gap are determined by the
electronic structure, and non-s wave symmetry gap favors the high-temperature
superconductivity. Why the high-temperature superconductivity occurs in the
metal region near the Mott metal-insulator transition is also explained.Comment: 7 pages, 2 figure
Pion superfluid phase transition under external magnetic field including inverse magnetic catalysis effect
Pion superfluid phase transition under external magnetic field including the
inverse magnetic catalysis (IMC) effect is investigated by the Pauli-Villars
regularized NJL model. Based on the Goldstone's theorem, we apply the massless
Goldstone boson ( meson) to determine the onset of pion superfluid
phase. The inverse magnetic catalysis effect is introduced by the magnetic
field dependent coupling , which is a decreasing function of magnetic
field. At fixed temperature and baryon chemical potential, the critical isospin
chemical potential for pion superfluid phase transition including IMC effect
increases as the magnetic field grows, which is similar as the case without IMC
effect. This demonstrates that magnetic field disfavors the pion superfluid
phase when considering or ignoring IMC effect. The critical isospin chemical
potential at fixed magnetic field, temperature and baryon chemical potential is
shifted to higher value by the IMC effect. Since it is more difficult to form
pion superfluid with weaker coupling.Comment: 5 pages, 3 figure
Wavelet/shearlet hybridized neural networks for biomedical image restoration
Recently, new programming paradigms have emerged that combine parallelism and numerical computations with algorithmic differentiation. This approach allows for the hybridization of neural network techniques for inverse imaging problems with more traditional methods such as wavelet-based sparsity modelling techniques. The benefits are twofold: on the one hand traditional methods with well-known properties can be integrated in neural networks, either as separate layers or tightly integrated in the network, on the other hand, parameters in traditional methods can be trained end-to-end from datasets in a neural network "fashion" (e.g., using Adagrad or Adam optimizers). In this paper, we explore these hybrid neural networks in the context of shearlet-based regularization for the purpose of biomedical image restoration. Due to the reduced number of parameters, this approach seems a promising strategy especially when dealing with small training data sets
Lie symmetry analysis, conservation laws and analytical solutions for chiral nonlinear Schrödinger equation in (2 + 1)-dimensions
In this work, we consider the chiral nonlinear Schrödinger equation in (2 + 1)-dimensions, which describes the envelope of amplitude in many physical media. We employ the Lie symmetry analysis method to study the vector field and the optimal system of the equation. The similarity reductions are analyzed by considering the optimal system. Furthermore, we find the power series solution of the equation with convergence analysis. Based on a new conservation law, we construct the conservation laws of the equation by using the resulting symmetries. 
- …