Five-fold local symmetry in metallic liquids and glasses

The structure of metallic glasses has been a long-standing mystery. Owing to the disordered nature of atomic structures in metallic glasses, it is a great challenge to find a simple structural description, such as periodicity for crystals, for establishing the structure–property relationship in amorphous materials. In this paper, we briefly review the recent developments of the five-fold local symmetry in metallic liquids and glasses and the understanding of the structure–property relationship based on this parameter. Experimental evidence demonstrates that five-fold local symmetry is found to be general in metallic liquids and glasses. Comprehensive molecular dynamics simulations show that the temperature evolution of five-fold local symmetry reflects the structural evolution in glass transition in cooling process, and the structure–property relationship such as relaxation dynamics, dynamic crossover phenomena, glass transition, and mechanical deformation in metallic liquids and glasses can be well understood base on the simple and general structure parameter of five-fold local symmetry.

Explicit solutions from residual symmetry of the Boussinesq equation

The Bcklund transformation related symmetry is nonlocal, which is hard to be applied in constructing solutions for nonlinear equations. In this paper, the residual symmetry of the Boussinesq equation is localized to Lie point symmetry by introducing multiple new variables. By applying the general Lie point method, two main results are obtained： a new type of Backlund transformation is derived, from which new solutions can be generated from old ones; the similarity reduction solutions as well as corresponding reduction equations are found. The localization procedure provides an effective way to investigate interaction solutions between nonlinear waves and solitons.

New solutions from nonlocal symmetry of the generalized fifth order KdV equation

The nonlocal symmetry of the generalized fifth order KdV equation(FOKdV) is first obtained by using the related Lax pair and then localizing it in a new enlarged system by introducing some new variables. On this basis, new Ba¨cklund transformation is obtained through Lie’s first theorem. Furthermore, the general form of Lie point symmetry for the enlarged FOKdV system is found and new interaction solutions for the generalized FOKdV equation are explored by using a symmetry reduction method.

Weak antilocalization and interaction-induced localization of Dirac and Weyl Fermions in topological insulators and semimetals

Weak localization and antilocalization are quantum transport phenomena that arise from the quantum interference in disordered metals.At low temperatures,they can give distinct temperature and magnetic field dependences in conductivity,allowing the symmetry of the system to be explored.In the past few years,they have also been observed in newly emergent topological materials,including topological insulators and topological semimetals.In contrast from the conventional electrons,in these new materials the quasiparticles are described as Dirac or Weyl fermions.In this article,we review our recent efforts on the theories of weak antilocalization and interaction-induced localization for Dirac and Weyl fermions in topological insulators and topological semimetals.

Abnormal breakdown of Stokes–Einstein relation in liquid aluminium

We present the results of systematic molecular dynamics simulations of pure aluminium melt with a well-accepted embedded atom potential. The structure and dynamics were calculated over a wide temperature range, and the calculated results（including the pair correlation function, self-diffusion coefficient, and viscosity） agree well with the available experimental observations. The calculated data were used to examine the Stokes–Einstein relation（SER）. The results indicate that the SER begins to break down at a temperature Tx（-1090 K） which is well above the equilibrium melting point（912.5 K）.This high-temperature breakdown is confirmed by the evolution of dynamics heterogeneity, which is characterised by the non-Gaussian parameter α2（t）. The maximum value of α 2（t）, α（2,max）, increases at an accelerating rate as the temperature falls below Tx. The development of α（2,max） was found to be related to the liquid structure change evidenced by local fivefold symmetry. Accordingly, we suggest that this high-temperature breakdown of SER has a structural origin. The results of this study are expected to make researchers reconsider the applicability of SER and promote greater understanding of the relationship between dynamics and structure.

Nonclassical Plane-crystallographic Groups and Their Applications Ⅲ

Six kinds of nonclassical periodic lattices with locally 10-fold rotational symmetries are proposed. They can be delineated via nonclassical plane-crystallographic groups. The projections on the planes of corresponding unit cells consisting of embedding polyhedra generate the periodic lattices, respectively. The Fourier-transform patterns of the periodiclattices have almost perfect 10-fold rotational symmetries, which are very similar to those displaying in the electron-diffraction patterns of so-called quasicrystals.

Vector meson effects on multi-Skyrmion states from the rational map ansatz

The roles of the lightest vector mesons ρ and ω in the multi-Skyrmion states are studied using the hidden local symmetry approach up to the next-to-leading order,including the homogeneous Wess-Zumino terms.The low-energy constants in the effective field theory are determined using the Sakai-Sugimoto model and the flat-space five-dimensional Yang-Mills action.With only two inputs,m_(ρ) and f_(π),it is possible to determine all low-energy constants without ambiguity.The vector meson effects can be investigated by sequentially integrating vector mesons,and their geometry can be elucidated by comparing the results using the low-energy constants estimated from the Sakai-Sugimoto model and the flat-space five-dimensional Yang-Mills action.We found that theρmeson reduces the masses of the multi-Skyrmion states and increases the overlaps of their constituents,whereas theωmeson repulses the constituents of the multi-Skyrmion states and increases their masses.Therefore,these vector mesons are crucial in the Skyrme model approach to nuclei.We also found that the warping factor,an essential element in the holographic model of QCD,affects the properties of the multi-Skyrmion states and cannot be ignored.

Critical state to achieve a giant electric field-induced strain with a low hysteresis in relaxor piezoelectric ceramics

Due to the extrinsic contribution of domain wall motions to electro-strains,the incompatibility of the large electro-strain with a low hysteresis in piezoelectric ceramics is a stumbling block for designing high-performance piezoelectrical actuators.Herein,we report a critical state in relaxor ferroelectric systems enables to enhance the electro-strain and to reduce the hysteresis simultaneously.A room temperature ergodic relaxor state dominated by nanodomains with different local symmetries can be obtained by introducing Bi(Zn_(1/2)Ti_(1/2))TiO_(3) into 0.73 Pb(Mg_(1/3)Nb_(2/3))O_(3)-0.27PbTiO_(3) matrix.Like the morphotropic phase boundary(MPB)in ferroelectrics,the coexistence of different local symmetries is capable of facilitating the transition from the ergodic relaxor state to the ferroelectric under the applied field due to the ease of polarization rotation,thereby leading to a giant electro-stain(0.24%)under an electric field of 50 kV/cm.Furthermore,the field-induced ferroelectric state with the long-range ferroelectric order can spontaneously reverse back to the initial ergodic relaxor state during unloading the electric field,which contributes to a low hysteresis(15.4%).The present work not only introduces a solid solution system with excellent electro-strain properties but also affords a guidance for manipulating the electro-strain behavior by modulating phase structures and domain configurations of piezoelectric ceramics.

Oblique parameters in gauged baryon and lepton numbers with a 125 GeV Higgs

In an extension of the standard model, where baryon number and lepton number are local gauge sym- metries, we analyze the effect of corrections from exotic fermions and scalars on the oblique parameters S, T, U. Because a light neutral Higgs h0 with mass around 12-126 GeV strongly constrains the corresponding parameter space of this model, we also investigate the gluon fusion process gg→h0 and two photon decay of the lightest neutral Higgs h0→yy at the Large Hadron Collider.

The radiative decay D^(0)→ K^(*0)γ with vector meson dominance

Motivated by the experimental measurements of D0 radiative decay modes, we have proposed a model to study the D0→ K＊0γ decay, by establishing a link with D0→ K＊0V （V=ρ0, ω） decays through the vector meson dominance hypothesis. In order to do this properly, we have used the Lagrangians from the local hidden gauge symmetry approach to account for Vγ conversion. As a result, we have found the branching ratio B[D0→ K＊0γ]=（1.55-3.44）×10-4, which is in fair agreement with the experimental values reported by the Belle and BaBar collaborations.