The σ-model and its renormalization in a dimensionally regularised normal product formulation

The σ-model is re-examined in the light of the reformulation of the normal product method in dimensional regularisation. It is considered both as a prime example of, and testing ground for, these methods, and to display the dimensionally regularised renormalisation of the model. Explicit and spontaneous symmetry breakings are considered, and the PCAC relation and Goldstone theorem are examined and proved in the one loop approximation. The renormalisation group equation coefficients are also obtained to this order. Both arbitrary (renormalised) parametrisations, and the mass shell parametrisation with finite counterterms are considered. It is found that, in contrast with other treatments, these counter terms remain finite in the infra-red limit of a massless symmetric Lagrangian.     

IR laser transtion in a nickel hollow cathode discharge

Laser oscillation in the infrared has been achieved in a nickel hollow cathode discharge. The 1.3968 µ laser transition is as-signed to Ni I.     

Inversion von schwingungselastischen Streudaten

Ohne Zusammenfassung     

Picosecond time-interval measurement and intensity correlations using the two-quantum photoelectric effect

A technique based on the two-quantum photoeffect has been used to measure second-order intensity correlations, pulse shapes from a mode-locked argon ion laser, and time delays in the picosecond domain. Good agreement was obtained between the mode distribution computed from the intensity autocorrelation data and that observed with a scanning Fabry-Perot when the laser was run in the mode-locked condition. Additionally, the contrast ratios observed in both the mode-locked and free-running condition were in good agreement with a theory by Weber and Danielmeyer.