$$a_{1}$$ meson-nucleon coupling constant at finite temperature from the soft-wall AdS/QCD model

We study the temperature dependence of the $$a_1$$ a 1 meson-nucleon coupling constant in the framework of the soft-wall AdS/QCD model with thermal dilaton field. Profile functions for the axial-vector and fermion fields in the AdS-Schwarzschild metric are presented. It is constructed an interaction Lagrangian for the fermion-axial-vector-thermal dilaton fields system in the bulk of space-time. From this Lagrangian integral representation for the $$g_{a_1NN}$$ g a 1 N N coupling constant is derived. The temperature dependence of this coupling constant is numerically analyzed.

Design of Energy Absorbing Metamaterials Using Stochastic Soft-Wall Billiards

Physical principles for designing cellwise artificial materials with energy-absorbing/harvesting and wave guiding properties are discussed in the present work. We analyzed the evolution of waves in a one-dimensional lattice of 3D massive potential wells with light particles inside. The potential wells were coupled with elastic springs and represented soft-wall versions of the so-called stochastic billiards. A billiard could switch from repelling to the stadium type as the parameter of shape changed its sign from positive to negative. We found that certain shapes of the potential wells/containers provided a one-directional trend of the energy flow from the chain of containers into the chaotically moving light inclusions by increasing their total kinetic energy. As a result, propagating waves became trapped by giving rise to standing waves with chaotic mode shapes with decaying amplitudes.

Thermal properties of light mesons from holography

The thermal properties of light mesons, including the temperature dependence of their masses (both screening and pole masses) and thermal widths, are studied in a two-flavor (Nf = 2) soft-wall AdS/QCD model. By solving the spatial correlation functions, we extract the screening masses (mscr) from their poles. The screening masses of pseudo-scalar (π) and axial-vector (a1) mesons increase almost monotonously with the increase of temperature. The screening masses of scalar (σ) and vector (ρ) mesons decrease at low temperature and increase at high temperature. The pole masses (mpole) and the thermal widths (Γ) are extracted from the temporal correlation functions and the corresponding spectral functions. The results indicate that the pole masses have local minima at low temperature and increase at high temperature. The thermal widths increase rapidly above the chiral crossover temperature Tcp, indicating the dissociations of mesons at high temperature. Furthermore, the degeneration of the chiral partners (π and σ, ρ and a1) above Tcp is observed from the screening and pole masses, revealing the chiral symmetry restoration at the hadronic spectrum level. Finally, we numerically verify that the spectral functions in the temporal regime are strongly related to the quasi-normal modes with complex frequencies ω0 = mpole− iΓ/2.

Flow pumping by external periodic shear applied to a soft interface

Flow pumping in viscous fluids is of prime importance in micro-fluidic applications. Here we show that a single colloidal particle in front of a soft wall, manipulated by external means like an optical tweezer, can pump the ambient viscous fluid. The particle, moving back and forth parallel to the soft wall, can produce an averaged net flow in a direction perpendicular to the wall. Using a perturbative scheme, we present the results. Analysis show that this flow in terms of capillary number, scales as $${\text {Ca}}^2$$ Ca 2 .