Spin Correlations in top quark pair production near threshold at the e−e+ e^- e^+ Linear Collider

We investigate the spin correlations in top quark pair production near threshold at the $e^- e^+$ linear collider. Comparing with the results above the threshold region, we find that near the threshold region the off-diagonal basis, the optimized decomposition of the top quark spins above the threshold region, does not exist, and the beamline basis is the optimal basis, in which there are the dominant spin components: the up-down (UD) component for $e_L^- e^+$ scattering and the down-up (DU) component for $e_R^- e^+$ scattering can make up more than 50% of the total cross section, respectively.Comment: 12 pages, 3 figures, minor modification

Can pro-environmental behavior increase farmers’ income?—Evidence from arable land quality protection practices in China

In China, agricultural non-point source pollution is one of the key factors limiting farmers’ income growth, and pro-environmental behavior can address agricultural surface pollution. Based on field survey data from 591 farmers in Xinjiang, China, this study empirically estimates the impact of pro-environmental behavior on farmers’ income growth. The results show that pro-environmental behavior plays a significant positive role in increasing farmers’ income, and the positive effect continues in the long run. Specifically, pro-environmental behavior can optimize the allocation of agricultural production factors, thus resulting in farmers’ income growth. The mechanism analysis shows that pro-environmental behavior affects farmers’ income growth by promoting the increase in the size of arable land and farmers’ willingness to transfer their land in the future. These findings indicate that a sound reward–punishment system for pro-environmental behavior should be established; training on pro-environmental behavior should be strengthened, and a mechanism for linking the benefits of pro-environmental behavior among stakeholders should be constructed

Monte Carlo Hamiltonian: the Linear Potentials

We further study the validity of the Monte Carlo Hamiltonian method. The advantage of the method, in comparison with the standard Monte Carlo Lagrangian approach, is its capability to study the excited states. We consider two quantum mechanical models: a symmetric one $V(x) = |x|/2$; and an asymmetric one $V(x)=\infty$, for $x < 0$ and $V(x)=x$, for $x \ge 0$. The results for the spectrum, wave functions and thermodynamical observables are in agreement with the analytical or Runge-Kutta calculations.Comment: Latex file, 8 figure

Ultrafast fluorescent decay induced by metal-mediated dipole-dipole interaction in two-dimensional molecular aggregates

Two-dimensional molecular aggregate (2DMA), a thin sheet of strongly interacting dipole molecules self-assembled at close distance on an ordered lattice, is a fascinating fluorescent material. It is distinctively different from the single or colloidal dye molecules or quantum dots in most previous research. In this paper, we verify for the first time that when a 2DMA is placed at a nanometric distance from a metallic substrate, the strong and coherent interaction between the dipoles inside the 2DMA dominates its fluorescent decay at picosecond timescale. Our streak-camera lifetime measurement and interacting lattice-dipole calculation reveal that the metal-mediated dipole-dipole interaction shortens the fluorescent lifetime to about one half and increases the energy dissipation rate by ten times than expected from the noninteracting single-dipole picture. Our finding can enrich our understanding of nanoscale energy transfer in molecular excitonic systems and may designate a new direction for developing fast and efficient optoelectronic devices.Comment: 9 pages, 6 figure

THE RESEARCH INTO RELATIVE HEIGHT OF TOTAL BODY CENTER OF GRAVITY OF MALES AND FEMALES AGED 17 -20 YEARS

By measuring the body center of gravity of 939 males and females aged 17-20 years in urban and rural areas when they stand at attention and hold up arms lathered, we found out the height and positions of the total center of gravity of them who were in different heights. It has great practical values to research the effect of body forms to the sports ability and also has great values to the selection of the sportsmen and technical analysis