Higher Dimensional Dark Energy Investigation with Variable Λ and G

Two phenomenological models of Lambda, viz. Lambda similar to ((a)over dot/a)(2) and Lambda similar to (a)double over dot/a are studied under the assumption that G is a time-variable parameter. Both models show that G is inversely proportional to time as suggested earlier by others including Dirac. The models considered here can be matched with observational results by properly tuning the parameters of the models. Our analysis shows that Lambda similar to (a)double over dot/a model corresponds to a repulsive situation and hence correlates with the present status of the accelerating Universe. The other model Lambda similar to ((a)over dot/a)(2) is, in general, attractive in nature. Moreover, it is seen that due to the combined effect of time-variable Lambda and G the Universe evolved with acceleration as well as deceleration. This later one indicates a Big Crunch.