Real Intermediate States Research Articles

Optical storage using refractive index changes induced by two-step excitation

Multiphoton excitation allows reversible photorefractive recording without the disadvantage of erasure during readout. The light intensity required for two-photon storage can be drastically reduced if two-step excitation via long†lived real intermediate states is used. Experimental results for LiNbO3:Cr3+ and LiTaO3:Cr3+ demonstrate the advantages of the two-step process. The energy and intensity requirements for optical two-step recording are within reach of presently available repetitively pulsed lasers.

Theory of Electron Tunneling via Real Intermediate States

A detailed theory of two-step electron transport through localized states is worked out. The quantitative results obtained are found to agree with existing experimental data. Analogies to the Anderson model of localized moments are discussed.

Tests ofCPandCPTInvariance in the DecayKL→ll¯

Pais and Treiman have studied the implications of $\mathrm{CP}$ and $\mathrm{CPT}$ invariance for the decay ${K}_{L}\ensuremath{\rightarrow}l\overline{l}$. We indicate how their results are modified when account is taken of the possibility of real intermediate states in this decay.

Pion Parameters from High-Energy Inelastic Interactions

The physical principle that a transition amplitude has a pole for real one-particle intermediate states was employed to study the photoproduction of secondary beams of high-energy particles. Photons were found to be very effective in initiating collimated beams of some very highenergy strongly interacting particles. The polology considerations are applied to further experiments in order to check their quantitative content, as well as to determine parameters of interest in pion physics such as the strengths of the ( pi pi pi pi ), ( gamma pi pi pi ), and ( pi pi kappa kappa ) interactions. A straig htforward extension is proposed to different inelastic processes in the work of Chew and Low. The main point is illustrated by comparing the diagrams for the one-pion contribution to elastic and inelastic nucleon-nucleon scattering. (B.O.G.)