Laser-assisted Positron Scattering Of The Hydrogen Atom

With the development of laser technology and the increase of laser intensity,the interaction between laser and matter is of increasing interest.Due to the complexity of the three-dimensional problem,in this paper we investigate the quantum dynamics of positron scattering from the hydrogen atom in one dimension.The propagation of the positron and electron wave functions are performed by solving the time-dependent Schr?dinger equation,and the populations in target excitation and positronium formation channels are obtained by projecting the final system wave function onto corresponding channel states.Strong interference fringes between the incident and reflected positron wave packets are observed in the reaction region.We further investigate the critical behavior of transition probabilities near the channel-opening threshold and find a strong competition between channels with different parity.The transmission ratios of the incident positron in each reaction channel as well as in the total scattering process are obtained.It is interestingly found that only the positronium formation in the ground state prefers forward scattering in both low-and high-energy scattering.With imposing the laser,we proceed to study the laser-assisted positron scattering from hydrogen atoms.We give the evolution of the spatial distribution of electrons and positrons as a function of time for different laser field strengths.The populations in target excitation and positronium formation channels are given.The multiphoton effect is also found by studying the momentum of the emitted particles.Finally,we find that positron and hydrogen atoms can form bound states in the onedimensional positron-hydrogen atom system.The properties of the bound states are investigated in detail.Our work provides the foundation for the future goal of positron scattering from the hydrogen atom in three-dimension.