Non-vanishing cosmological constant Λ, phase transitions, and Λ-dependence of high energy processes

It is pointed out that a collider experiment involves a local contribution to the energy–momentum tensor, a circumstance which is not a common feature of the current state of the Universe at large characterized by the cosmological constant Λ0. This contribution may be viewed as a change in the structure of space–time from its large scale form governed by Λ0 to one governed by a Λ peculiar to the energy scale of the experiment. Possible consequences of this effect are explored by exploiting the asymptotic symmetry of space–time for non-vanishing Λ and its relation to vacuum energy.