MOMENTUM AND DENSITY-DEPENDENCE OF THE MEAN-FIELD IN NUCLEAR-MATTER

The momentum and density dependence of the mean field in nuclear matte r has been studied with phenomenological effective interactions with p articular emphasis on the influence of the functional form of the inte raction in determining the high density and high momentum behaviour of the mean field. Emphasis is also given to choosing the effective inte raction in a form simple enough to permit analytical calculations of v arious properties of nuclear matter with a minimum number of adjustabl e parameters. These simple effective interactions are found to have a zero-range density-dependent part similar to Skyrme interactions and a long-range density-independent part of conventional form, such as Yuk awa, Gaussian and exponential. It is observed that the high density an d the high momentum behaviour of the mean field in nuclear matter is e ssentially governed by the nature of the density dependence and the pr ecise functional form of the long-range part of the exchange component of the effective interaction. The parameters of these interactions ca n be constrained to obtain a mean field in nuclear matter which is ind ependent of the functional form of the exchange interaction in the ran ge of momentum k = 0-5 fm(-1) and up to a density four times the stand ard nuclear matter density. However, beyond this range the functional form of the exchange interaction becomes important in determining the momentum and density dependence of the mean field in nuclear matter.