Based on relativistic constituent quark (RCQ) model, the electric and magnetic form factors are analyzed. The ratio of the two form factors for the proton , which is an image of its charge and magnetization distributi...Based on relativistic constituent quark (RCQ) model, the electric and magnetic form factors are analyzed. The ratio of the two form factors for the proton , which is an image of its charge and magnetization distributions, is calculated in the light-front formulism of RCQ model. Recently, this ratio was measured at the Thomas Jefferson National Accelerator Facility (JLab) using the polarization technique. The new data presented span the range and are well described by a linear Q<SUP>2</SUP> fit. Also, the ratio reaches a constant value while Q<SUP>2</SUP> becomes larger than 2 (GeV)<SUP>2</SUP>. Our calculation results are presented and appear to be consistent with the experimental ones.展开更多
In this paper we investigate the time-machine problem in the electromagnetic field. Based on a metric which is a more general form of Ori＇s, we solve the Einstein＇s equations with the energy-momentum tensors for ele...In this paper we investigate the time-machine problem in the electromagnetic field. Based on a metric which is a more general form of Ori＇s, we solve the Einstein＇s equations with the energy-momentum tensors for electromagnetic field, and construct the time-machine solutions, which solve the time machine problem in electromagnetic field.展开更多
In the present work, the entropy and internal energy of a GaAs cylindrical quantum dot in the presence of an applied magnetic field is studied. For this purpose, the Tsallis formalism is applied to obtain internal ene...In the present work, the entropy and internal energy of a GaAs cylindrical quantum dot in the presence of an applied magnetic field is studied. For this purpose, the Tsallis formalism is applied to obtain internal energy and entropy. It is found that entropy and internal energy are continuous function and they are zero at special temperatures. Entropy maximum increases with increasing dot radius. Internal energy increases by increasing magnetic field.展开更多
We investigate bias and different barrier thicknesses effects on quantities related to spin and charge currents in MgO-based magnetic tunnel junctions. Using the non-Equilibrium Green＇s function formalism, we demonst...We investigate bias and different barrier thicknesses effects on quantities related to spin and charge currents in MgO-based magnetic tunnel junctions. Using the non-Equilibrium Green＇s function formalism, we demonstrate that the in-plane and out-of-plane components of the spin-transfer torque have asymmetric and symmetric behaviors respectively. Magneto-resistance also decreases with increasing barrier thickness. The Landau–Lifshits–Gilbert equation describes the dynamics of the magnetization made by spin transfer torque. Increasing in spin current above its critical value or smaller the magnet reduces the switching time which is major result for making of new memory devices.展开更多
基金The project supported by the Science Foundation of Chinese Academy of Engineering Physics under Contract No.42103 and for Research Doctor Subsidizes (2001)
文摘Based on relativistic constituent quark (RCQ) model, the electric and magnetic form factors are analyzed. The ratio of the two form factors for the proton , which is an image of its charge and magnetization distributions, is calculated in the light-front formulism of RCQ model. Recently, this ratio was measured at the Thomas Jefferson National Accelerator Facility (JLab) using the polarization technique. The new data presented span the range and are well described by a linear Q<SUP>2</SUP> fit. Also, the ratio reaches a constant value while Q<SUP>2</SUP> becomes larger than 2 (GeV)<SUP>2</SUP>. Our calculation results are presented and appear to be consistent with the experimental ones.
基金Supported by the Start-up Fund of Fuzhou University under Grant No.0460022346
文摘In this paper we investigate the time-machine problem in the electromagnetic field. Based on a metric which is a more general form of Ori＇s, we solve the Einstein＇s equations with the energy-momentum tensors for electromagnetic field, and construct the time-machine solutions, which solve the time machine problem in electromagnetic field.
文摘In the present work, the entropy and internal energy of a GaAs cylindrical quantum dot in the presence of an applied magnetic field is studied. For this purpose, the Tsallis formalism is applied to obtain internal energy and entropy. It is found that entropy and internal energy are continuous function and they are zero at special temperatures. Entropy maximum increases with increasing dot radius. Internal energy increases by increasing magnetic field.
文摘We investigate bias and different barrier thicknesses effects on quantities related to spin and charge currents in MgO-based magnetic tunnel junctions. Using the non-Equilibrium Green＇s function formalism, we demonstrate that the in-plane and out-of-plane components of the spin-transfer torque have asymmetric and symmetric behaviors respectively. Magneto-resistance also decreases with increasing barrier thickness. The Landau–Lifshits–Gilbert equation describes the dynamics of the magnetization made by spin transfer torque. Increasing in spin current above its critical value or smaller the magnet reduces the switching time which is major result for making of new memory devices.
